This document was last updated December 6, 2019, under Release 12. Information on the latest RTGUI release is on-line at doc.rtgui.com .
Read the FAQ . - Read or Join RTGUI on "groups.io".
This software may be freely distributed and copied for non-commercial personal use, provided that the program and the documentation are not modified in any way. Donations are accepted via Paypal to support the author's development of this and other software. This program may not be sold, and is provided without any guarantee or warrantee whatsoever. Use this program at your own risk. You should watch your telescope carefully whenever it is in motion, and stop it immediately if any problem is detected. The author is not responsible for any possible equipment malfunctions or injuries caused by this software, or by careless use of mechanized telescopes. Do not utilize "Goto" functions in the daytime to avoid the danger of permanent eye damage from slewing in the vicinity of the sun. Do not attempt to observe the sun unless you are using a proper commercially-manufactured solar filter.
Primary Features of RTGUI ( "RTGUI+S"):
System Requirements and Installation: Runs on practically any PC running Windows 95/98/me/xp, Windows NT 4, Windows 2000, Windows Vista, Windows 7, or later. Requires only minimal system resources. Self-extracting archive rtgXXsfx.exe by default will extract its files into c:\Program Files\rtgui, although you can select any directory that you want. RTGUI must be installed in a directory where everyone who will use it has write access, and in the typical Windows system write access to c:\Program Files may be restricted to the administrator. The first time that RTGUI+S runs, it prompts you to specify your telescope type and COM port. It only displays COM ports between 1 and 64 that exist, and are currently free; if some other application is using a COM port, or it will not open for any other reason, RTGUI will not allow you to select it. If you do not have a free COM port, you cannot use the telescope or GPS functions of RTGUI.
RTGUI also tries to create a shortcut to the desktop for itself, at the time it first runs on your system. If you do not want the shortcut, just drag-and-drop it in into the Recycle Bin, it will not be regenerated. (Automatic creation of shortcut requires Windows Scripting Host, which may not work on some older Windows systems owing to lack of that function.)
Uninstallation: Since RTGUI does not make any changes to the Registry, to remove it from the system just use Windows Explorer and "drag and drop" the rtgui directory into the Recycle Bin, then delete the Desktop Icon (right-click, and select delete).Getting Started: By default, RTGUI is a real-time program, and it begins in real-time mode, using GUI operation. Many of the buttons also have keyboard shortcuts, which are displayed. In that case, either the mouse or a keypress may be used to invoke the function. (When doing a lot of searching, using the keyboard will allow you to work more quickly.)
Upon entry, RTGUI reads the default location file RTGUI.HOM, and the Windows sysstem clock, from which the other times are derived. RTGUI provides a real-time display of local clock time, UTC (GMT), and local Sidereal Time. So long as you are operating in real-time mode, the program will folow the object you have selected, and track its progress in altitude and azimuth. If a "+" character appears next to the UTC display, it means that the date in Greenwich is one day later than the date displayed. If a "-" character appears next to the UTC display, it means that the date in Greenwich is one day earlier than at your location.
Fields that can be modified by the user (example: latitude, longitude, time, date) are indicated by a command button. The user is then prompted for new values to be entered (or click on "CANCEL" to keep the previous data unchanged). You need to know your latitude and longitude with reasonable accuracy. This information can be downloaded (or copied) from a GPS device, from a GPS-equipped telescope, obtained from a map, or from many places on the Web (for example, the U.S. Gazetteer). (If you have decimal fractions of a degree, they must be converted to minutes of latitude and longitude - just multiply the fractional part by 60 to get minutes. If even that's too much trouble, just round off to the nearest whole degree - for casual observing it won't matter.)
When you have entered the proper data for your telescope and for your location, you can click the "SAVE" button to store it in a location file. The default filename for this is RTGUI.HOM. RTGUI will automatically read and load the file RTGUI.HOM when it starts up. In this file you should save the location for your home, or wherever you observe from the most. You do not have to repeatedly enter your latitude, longitude, and telescope data each time you start the program. If you observe from more than one location, you can create different location (or ".hom") files and load each one appropriately. The name of the location file loaded is displayed in the bottom left-hand corner of the main form. This file also stores other options such as the model of Goto telescope you are using (if any), the Com port you are using to communicate with the telescope, the Com port you are using to communicate with a GPS device (COM1-COM64), the telescope size and light pollution levels (used to set default magnitude limits). If you observe from different locations, you can save the data for each location using different file names, then press the "LOAD" button to list them and load one accordingly. For example, if you sometimes drive up to Mt. Palomar campground to observe, you might create a file palomar.hom containing the data for that location.
Some fields cannot be updated because they contain data that is derived from other sources; for example, the Sidereal Time is derived from your location and from the current time. The names in the object name fields (1-5) can be copied to the Windows clipboard by double-clicking over those fields.
Setting the Date or Time: You can tell RTGUI to set the time to some non-real time or date, in which case time will be "frozen" and all real-time updates will cease. A button appears to remind you that you are no longer in real-time mode, and to facilitate the return to it; you can also return to real time by pressing "Cancel" when the message box appears to change the date or time. The Julian Date is displayed whenever you click on the Time or Date field (and not just the whole-number date, but to 5 decimal places of a day). RTGUI will use whatever time zone is set in your Windows system. The date will be displayed in U.S. format (month, day, year) for observers in North America, and as "day, month, year" elsewhere. Daylight Savings time will be used whenever it is set in your Windows system. A few localities use time zones that are not an even number of hours different from UTC; these are now handled correctly. The option to set UTC to a value different than your time zone in Windows is no longer supported. In the unusual case where you want to analyze the sky for some other location, using some other time zone, just temporarily set the Windows time zone for that location (right-click on the time displayed by Windows, click "Adjust Date/Time", click "Time Zone", and select from the slide bar), afterwards setting it back again.
Selecting an Object: RTGUI allows you to select an object, for which the altitude and azimuth are displayed in real time. You will see these values constantly changing, as the object marches across the sky. This information is updated continuously, for as long as you wish.The time of the object's rise, transit (crossing the meridian, due south or due north), and setting from your location is also displayed. If the object is a solar system object, its RA and DEC will also be continuously updated in real-time (although this is scarcely necessary for any object except the moon).
Using GOTO Telescopes: Click the "Options" button to select or change your Goto telescope, and select the COM port to be used. Click on the "options" button to load the Options form. To select or change the telescope port, click on "Select COM port for telescope," then click on one of the available ports listed. Your selections are recorded if you click the "Save" button afterward, or choose "Yes" when asked to save configuration changes when you exit the program. Supported "Goto" telescopes can be made to slew directly to the selected object by pressing the "Goto" button when that button becomes visible. Your telescope must already be properly aligned before any Goto functions can be performed. Alignment is performed in the usual way in accordance with the telescope manufacturer's instructions, using the telescope's hand controller. RTGUI+S cannot help you to align your telescope. Your telescope's data connector must be attached to one of your computer's serial ports (COM1 - COM64) in accordance with the instructions provided in your telescope's manual, using either a serial cable, or a USB-to-serial adapter. Bluetooth serial ports can be used, if your telescope can receive data via Bluetooth. Most of the newer computers do not have serial ports, but have only USB connections. In that case, you need to purchase a USB-to-Serial adaptor, which is widely available for about $40 or less. Connect the computer to your telescope prior to alignment, but do not attempt to use the RTGUI+S Goto until after the scope is successfully aligned. RTGUI connects to the telescope in the same manner as popular astronomy programs such as The Sky, Cartes du Ciel, etc. However, RTGUI does not use the ASCOM telescope drivers like many other programs do, in part because those drivers are quite large and contain many functions that are not needed.
The user will not be allowed to attempt to slew to an object that is not at least a degree above the horizon. Also, the user will not be allowed to "Goto" an object when the program is not running in Real-Time mode. However, if the time on your telescope or on your computer is set incorrectly, or if your telescope alignment is incorrect, this may cause an attempt to slew to an object below the horizon, or to the sun. You must always watch your telescope when it is in motion, and be ready to stop its motion if something goes wrong.
GOTO Telescope Groups: The following describes the general families of Goto telescopes. The Scope Selection form breaks down this list even further, and asks you to select your specific telescope. Please choose carefully, because you may encounter problems if your selection is not correct.
The Scope Selection form will appear the first time you run RTGUI, or when you click on the SCOPE button. It will continue to appear until you make a scope selection and save it in your default configuration file RTGUI.HOM. You should also save it in any other location files that you use.
0 = No GOTO telescope.
1 = Celestron NexStar GPS Family: 8 / 9.25 /11
; Nexstar5i/8i; Nexstar 60/80/114/4 made since 2002, CG\ CGE and Advanced Series
with GoTo
2 = Original Celestron NexStar 5/8
3 = Old NexStar 60, Nexstar
80, Nexstar 114, Nexstar 4 (2001 and before) and Tasco StarGuide
4 = Meade LX series, or Autostar and compatibles (including the
Mel Bartels Controllers, Vixen SkySensor 2000, Ioptron MiniTower, and
probably the Losmandy Gemini control system, Astro-Physics AP series,
Astro-Electronic FS-2 ).
5 = Goto Scopes not listed above but
supported by Skychart: Orion Intelliscope, Tangent Encoders, and other scope
types with ASCOM drivers available.
Notes for Small Nexstar Telescopes: The "old" Celestron Nexstar 60, Nexstar 80, or Nexstar 114 were manufactured until the latter part of 2001. If you are not sure which version you have, the old controller offers only the "Auto-Align" mode for alignment, the new controller offers several choices. With the old small Nexstars (60, 80, 114) and the original Nexstar 4, you must press a key on the telescope keypad between successive slews, or your telescope may lock up and require re-alignment. A reminder is provided for this purpose in the program, but it does nothing for the scope except to remind you to use the keypad. With the new small Nexstars, you must put the scope in "RS-232 Mode" before it will accept commands from the PC. Use the "Utilites" menu in the Hand Controller to set this. While in RS-232 mode, the PC has full control over the scope's GOTO functions.
Notes for Celestron Nexstar Telescopes:
The PC data cable that you use between the PC and the telescope plugs
into the bottom of the Hand Controller, the same as most other standard
astronomy software packages. Note that this is not the "programming cable" that
was used by the hcAnywhere or NexRemote hand controller replacement
program, and is used to update the telescope's firmware. Some of the firmware in
the newer Nexstar Hand Controllers has difficulty communicating with certain
PCs' serial ports. According to an old web page by software developer Andre
Pacquette (no longer up):
"Serial problem with HC: Not all PC serial ports are made equal.
When not in use, most serial ports idle with a stop bit. However, some serial
ports send a continuous start bit (break signal) when not in use. If the HC
serial port receives a continuous start bit, it gets confused or bogged down
and has difficulties sending characters the next time you connect. For
instance, if you try connecting to the HC with "TheSky" you'll get errors 9/10
times. Often, BIOS upgrades are available that will change the serial port
behaviour and work around the problem. Also, you could get a serial-to-USB
device and hope that it idles with stop bits. Either way, this is a bug with
the serial handling on the HC and hopefully Celestron will correct it on the
next spin.".
RTGUI has implemented a work-around for this problem
by inserting delays of at least 5ms between the characters, which seems to work
much better. If software on your PC's serial port has had difficulty controlling
your Nexstar, RTGUI+S may work more successfully. Also, with Rel. 8.4 new
character handling has been introduced for users of the Celestron NexRemote
program, with additional character delays when using its Virtual Serial
Port.
RTGUI can read object positions from Celestron Goto telescopes in group 1. Press "Object/Load Position from Scope" to read the position of the object currently being observed. You must specify at least one name for the object. You can also add the new object to a catalog. (Small Nexstars must be in "RS-232 Mode" when communicating with the PC).
Notes for Meade Telescopes: RTGUI can read object positions from Meade Goto telescopes. Press "Object/Load Position from Scope" to read the position of the object currently being observed. You must specify at least one name for the object. You can also add the new object to a catalog.
You can read the current location, and optionally set the system time, from a Meade Goto scope. It does not matter whether the data was obtained from the scope's GPS, or entered manually. Click "Load", then "Load from Meade". Some Meade scopes adjust for Daylight Time in downloading this data, while others do not. If your PC is currently observing Daylight Timse and you download a time that is an hour off, try changing your selection between "Autostar" and "LX-200", or one of the other scopes in that group, until you get the correct result.
You can upload the current location and system time to a Meade Goto telescope. Click "Scope", then "Upload". This sets the latitude, longitude, date, time, and GMT offset (actually, time zone) to whatever value is presently set in RTGUI+S. If you have downloaded that data from a hand-held GPS unit, you have interfaced your telescope to the GPS, in essence converting a non-GPS scope into one having a GPS! Remember that interfacing a Meade scope to a GPS is a two-step process, involving different data cables. You connect the GPS unit to the COM port you have selected for the GPS, and click "Load," then "Load from GPS". You also connect the telescope to the COM port you have selected for the telescope, and then click "Upload to Meade". The upload must take place before the scope is aligned. When uploading data, your hand controller should be in its "idle" state, displaying "Telescope". Otherwise, you may be in "edit" mode without realizing it, and the data that you upload may be overwritten.
When using the Meade LX-200 protocol, the telescope must not be in "Long Format Mode." The user must ensure that this mode is turned off.
Notes for Goto Telescopes not listed as supported above but supported by Skychart: Skychart is a much larger, full-featured program, and has full support for ASCOM Drivers and other Goto scopes that RTGUI does not. However, the Goto function can be supported by RTGUI indirectly, as a two-step process. You can use RTGUI to select the objects you want to view, take notes on them, etc. When it is desired to perform a Goto, the Goto button will bring up Skychart centered on the selected object, from which you then click Telescope/Slew. Skychart must already be properly configured for your telescope, and connected to it, and the ASCOM drivers must be loaded. In this case, Skychart will have full control of your telescope COM port.
Best of the Sky: The easiest way to find objects to observe is to just press the Best of the Sky button to have RTGUI+S suggest the most interesting objects for viewing in a small telescope, based on your location and the time: well-placed planets, Messier objects, NGC and IC objects, and double stars. The list is passed through twice: the first time giving you the "Super Star" objects like Saturn and M42, the second time the merely wonderful objects like M15. You can move forward and backward along the chain (using "Next" and "Previous") as much as you like. This will be very helpful for beginners who are not yet familiar with the constellations, and are unsure of what objects to search for. This is also useful for selecting objects to show the public at star parties. Deep-sky objects and double stars must be at least 20 degrees elevation to be selected (except for objects whose maximum altitude is less than 40 degrees, in which case the object must have attained at least half its maximum altitude). If a telescope size is selected on the Options form, appropriate magnitude limits will be applied to this search (excluding objects not likely to be seen well). Mercury will be selected if it is 5 degrees or higher. Venus, Jupiter, and Saturn will be selected if they are at least 10 degrees elevation. Mars will be selected if it is at least 15 degrees elevation, and Uranus if it is at least 20 degrees.
Catalog Searches: Once RTGUI is running, you can can look up objects by name in a catalog.The default catalog for RTGUI+S is full.rtg. All attempts to find objects will initially be made in this catalog. You may change catalogs at any time by clicking on the "Catalog" button. A "simple" search attempts to match one of the names of the object. Each object has at least one name, and may have as many as five. Names are at most 12 characters long, and searches are not case-sensitive. To find an object, press the (simple) "Search" button and enter its designation, such as M31. If it is found, a "Next Match" button appears which gives you the option to search for another object matching the same character string. After two or more matches are found, a "Previous Match" button appears to allow you to walk backwards down the list of matching entries. You can walk up and down down the list of matches in either direction as long as you like. There is no limit to the number of saved matches you may accumulate, so long as your PC has enough memory.
Deep-sky objects in full.rtg also contain their constellation name and object type. Constellation names for deep-sky objects are fully spelled out up to 12 characters, as are the common names of stars or deep-sky objects. You can also search using LMC or SMC for objects in the Magellanic Clouds. You can search for objects named VIRGO, Orion, GALAXY, or globular. Spaces and case are ignored during catalog searches, so m35 and M 35 are the same. Any unique truncation of a name is permissible; for example, GLOB will do for finding a Globular. A single Wild-Card character "*" can be used at the beginning or in the middle of a name, to substitute for any character or characters. Only one wild-card character may be included in each name string. There is no need to use a Wild-Card character at the end of the string, because matches of partial names are automatically accepted. For example, M1 also matches M11, M12, etc. While spaces are ignored during searches, a single space may be placed at the end of a search string to disallow partial name matches. For example, "SAGITTA" will match the constellations "SAGITTA" and "SAGITTARIUS"; however, "SAGITTA " will match only the former.
The Search Wizard makes it easy to select exactly the kind of objects that you want to see. You tell it what you want to see: deep sky objects (of all kinds, or only certain kinds), double stars, etc., and whether you want to limit your search to a particular visible constellation. It fills in the search parameters for you. You can also fill in the parameters yourself using Detailed Search, which offers the opportunity to specify one or two names that must be matched (example: Globular and Lyra .) You can also specify additional parameters such as minimum altitude, maximum altitude, and magnitude, in essence creating your own custom "tour." For example, you might choose to locate all galaxies having an elevation of at least 35 degrees, brighter than magnitude 11. Because some telescopes (and some peoples' necks) would prefer not to be looking directly overhead, you can set a maximum altitude to the highest position you can observe comfortably. The default value is 90 degrees, so if you ignore this field it will have no effect. RTGUI pauses after finding each object for as long as you like, tracking its position all the while, until you tell it to look for another object. If you want to observe galaxies, you may optionally enter one of the search terms Pair, Cluster, Group, Interacting, Seyfert, or LowSurfaceBr. (The list of such designations is probably not exhaustive.)
Default Magnitude Limits: If you select a telescope size on the Options form, this generates a default magnitude limit that will be applied to all searches. This limit is displayed each time you use the Search Wizard; you are free to override it with any other value. You can also clear the Magnitude field to override all magnitude limits for the search (zero is not the same as clear). This limit does not represent the faintest object visible; however, it is an estimate of the faintest deep-sky (extended) object that is likely to be visible. The magnitude limit is also applied during Simple Searches based on constellation or object type. However, an object whose primary name (first name field) exactly matches what you entered is always accepted, no matter what default magnitude limit may be set. For example, the galaxy NGC 553 in Pisces is quite faint at magnitude 14.1. However, if you enter a search for that exact name, it will be found no matter what your default limits. That name also matches NGC 5530, NGC 5531, etc., but those inexact matches will only be displayed if they are within the magnitude limit. NGC 553 will only turn up in inspecific searches for Galaxy or Pisces if within the magnitude limit.
Potentially modifying the default magnitude limit is the Sky Description selected in the list box below the telescope size. The default magnitude limit is decreased by 1.5 for each degree of sky degradation indicated below Rural. Because the telescope and sky descriptions are stored in each unique location file, you can have several different ones that are loaded as appropriate. For example, you might use an 18" club telescope at a dark rural site, and a 4" scope in your suburban backyard. By saving these parameters in different location files, you will generate searches that are appropriate for each one.
If you find that RTGUI searches are returning many objects that you are unable to see, just set your telescope size one size smaller. This will cause the fainter objects to be ignored. If you believe it is ignoring objects that are potentially visible to you, set it one size larger. To completely disable all default magnitude limits, just set the telescope size to the first entry, Unspecified.
Saving Matching Objects: After you begin a search, a button appears to give you the option to Save Matches resulting from that search. Pressing that button takes you directly to the end of the chain of matching objects (the same as pressing the Next Match button repeatedly), and also causes all of the matching objects to be written to the file matches.txt. A message box asks if you want to view the matches. Choosing "yes" causes the file matches.txt to be opened by the default text editor on your system (Notepad or equivalent), from which it can easily be printed or renamed, if desired. This file remains only until the next search is begun, at which time it is overwritten. If you wish to keep it you will need to rename it, or copy it somewhere else.
The data fields for the matching objects stored in matches.txt are
separated by commas, making it easy to import them into spreadsheet programs
such as Excel. This allows you to keep "Best Of the Sky" lists for different
months in different locations, or lists of visible galaxies, etc. The contents
of the columns for catalog objects are:
1 -5 (first row): the five name
fields (some may be blank)
6 (second row): Object altitude in degrees
7:
Object azimuth in degrees
8: Object RA in hours and minutes
9: Object
Dec in degrees and minutes
The column layout for planets is: Name;
Distance in AUs; Elongation (in degrees) morning or evening; altitude; apparent
size in Seconds of arc. Information about the search itself are contained
in the first three lines of the text.
The default catalog full.rtg is made up from the following:
Messier Catalog: containing all 110 Messier objects, with object type, NGC number, and popular name where appropriate. You may search, for example, for DUMBBELL or even DUM. Thus, M27, NGC 6853, and DUMBBELL all refer to the same object. You may find that object in the FULL catalog using any one of these names. Each object is given an object type of up to twelve letters, either Globular, Galaxy, BrightNebula, Planetary, OpenCluster, or STARS (for Messier's little errors!). Each item also contains its constellation name, fully spelled out (up to twelve letters).
NGC Catalog and Index Catalog: contains a unique and updated version of the NGC catalog of over 7,800 objects, which was carefully compiled by incorporating the latest revisions from the NGC/IC Project. The NGC list is followed by the full Index Catalog (IC) containing 5,385 objects, also uniquely updated using the latest data from on-line databases.
NGC objects are found by entering NGC followed by their numbers, up to 4 digits (from NGC 1 to NGC 7839). Index Catalog objects are found using the prefix IC (example: IC 434 ). Most of the well-known deep-sky objects can also be found by their common names (HELIX, Veil, etc.), using 12 letters or less. Messier objects will not "reappear" in searches of the NGC list. Much NGC data concerning object types, magnitudes, and in a few cases, positions, has been manually updated beyond the standard NGC/RNGC lists, using other sources such as the NGC/IC Project, SIMBAD, the PGC, NED, etc. Unfortunately, the information is not available in any one place. But now, magnitude values and object types missing from the standard NGC/RNGC have been nearly all filled in, resulting in far more accurate object searches.
The "official" IC (Index Catalog) is frankly in pretty bad shape. Approximately 40% percent of the objects on the list are labelled as "unidentified/unknown" (!!!), and far more have no magnitude information. Many IC objects have incorrect object types. For example, the "official" IC catalog lists IC 3065, 3077, 3080, 3093 (among others) as "bright nebulae" in Coma Berenices. Of course they are galaxies. (Try finding a "bright nebula" in the Realm of Galaxies. Right.) IC 3421 is listed as an "open cluster" in Coma, but is also a galaxy. The "bright nebulae" IC 2754 and IC 2761 in Leo simply do not exist. Most of the "unidentified" IC objects do not exist, although many of them turned out to be galaxies - and not all of them are faint.
I have filled in as much missing information as possible on object types, magnitudes, etc., using on-line sources. For some entries in the NGC and IC catalogs, magnitudes could not be found in any on-line catalogs. In that case, the magnitude will be displayed as "Unspecified". (In the catalog it is represented as 99, rather than zero, so it will not be found when searching for brighter objects.) NGC and IC objects without magnitudes specified will probably be quite faint. Many of the filled-in magnitudes for IC objects are estimations of visual magnitude, extrapolated from photographic or infrared magnitudes, or from magnitude estimates made by observers, where visual magnitude data was unavailable. They should be sufficiently accurate for you to tell whether or not the object will be visible in your telescope.
So far as I am aware, there is no other astronomy program to incorporate as much updated and revised deep-sky object catalog information in its database as RTGUI. This results in far more accurate object searches: you will not waste time searching for objects that cannot be seen, and you also will not miss out on seeing objects that are visible.
Caldwell Catalog: Contains all 109 objects in the Caldwell Catalog, as popularized by astronomer Patrick Moore. Most of the Caldwell objects already appear in the NGC or IC catalogs; in those cases, the Caldwell number has simply been added to the object's other designations.
The Herschel 400 Catalog. To supplement the Messier and Caldwell catalogs, The Herschel 400 has been created by the Astronomical League as a list of Deep Sky objects for observers in the Northern Hemisphere. (See http://www.astroleague.org/al/obsclubs/herschel/hers400.html . Sir William Herschel (1738-1822)was a noted astronomer who discovered the planet Uranus. He made one of the earliest lists of deep-sky objects that he observed in his telescope. The Herschel 400 consists of the 400 most significant objects in Herschel's catalog. The intention is that observers who have already seen all 110 objects in the Messier catalog would want a longer list of deep-sky objects that were still relatively easy to observe.
The Astronomical League offers a certificate to those who observe all 400 objects and properly record their observations. The requirements for the certificate are given here: http://www.astroleague.org/al/obsclubs/herschel/her400cl.html .
The Herschel400.rtg catalog for RTGUI was created by Rok Vidmar, with additional work by Robert Sheaffer. The original data was excerpted from FULL.RTG. It can be used in conjunction with the Search Wizard (requires RTGUI version 8.5 or later) to present the user with a list of Herschel 400 objects appropriate for viewing at the selected time. You can use the standard features of the Search Wizard, including selecting objects by constellation, by elevation in the sky, etc.
The Yale Bright Star Catalog (HR), Version 5. It contains 9096 stars brighter than magnitude 7 (although not all stars of magnitude 7 or brighter are included.) Stars can be found in this catalog by their Bayer (Greek letter) designation (Example: Alp Ori) if one exists, Flamsteed numeric designation (12 And ) if one exists, or Durchmusterung number (D +44 4550 ). Some stars have Bayer and Flamsteed designations, and both are usually included. A star can also be found by its number in the Yale Bright Star Catalog (Harvard Revised) by placing HR in front of the number (HR 2491), or by its SAO designation when preceeded by SAO (SAO 131907) , but only for those SAO objects bright enough to be contained in the Bright Star catalog. (The auxiliary catalog PPM contains the full SAO catalog.) In the case of some multiple stars, there is a number following the Greek letter (GAM1 ARI) that must be allowed for in searches. The Search Wizard will create for you the proper search parameters. I have added over 100 common star names such as Sirius or Polaris. I have also added 3-letter constellation abbreviations for stars that do not have Bayer or Flamsteed designations.
Double Stars: All stars in the Yale Bright Star Catalog (HR) that are designated as double (or multiple) in the huge Washington Double Star Catalog, and potentially observable in at least some amateur telescopes are so designated in full.rtg, making over 2,500 searchable double stars. They have been flagged by the designation Dbl . You can find them easily using the Search Wizard. Pairs whose separation was not at least 0".3 were ignored, as were entries with incomplete information. (The huge Washington Double Star catalog, wds.rtg, containing 84,486 entries is available as a separate auxiliary catalog. It does not use (or need) the identifier dbl, since all entries represent double stars. The version of the WDS updated in Jan., 2006 is compatible with the new Search Wizard, and also contains a few data corrections.)
Following Dbl is the separation in seconds in the format 1".5 , and following that is the magnitude of the fainter star. The combined magnitude of both stars is already visible in the magnitude field. This is not the same as the magnitude of the brighter star. In the case where the two stars are relatively close in brightness, the magnitude of the brighter component will be approx 1/2 magnitude fainter than the combined magnitude. In the case where the two stars differ by at least 2 or 3 magnitudes, the magnitude of the brighter star will be almost the same as the combined magnitude. Thus in the case where the combined magnitude is 5.5, and the fainter component is magnitude 6.2, in reality the two stars will be of nearly equal magnitude. If you want to know the magnitude of the primary star alone, consult wds.rtg. Double-click the SAO number from full.rtg, then paste it into the search box after switching to wds.rtg.
In the case of multiple stars, the total number of members is given in full.rtg in the format Dbl:5. The separation and magnitude of the most prominent companion star is also given For more information about multiple star systems, consult the WDS. The WDS contains one entry for each pair, so a system of five stars should contain at least four separate entries (AB, AC, AD, AE, and possibly BC, etc.). To get more information on multiple star systems from wds.rtg, hit next repeatedly (or save matches) to get information on all members of that system.
You can find all listed double stars in a given constellation using the Search Wizard. All of the double stars in the Astronomical League Double Star Certificate list have been included, and added to the catalog where they don't have an HR number. Some interesting doubles not in any of these catalogs or lists have been added, with either a HD (Henry Draper catalog) number or WDS identifier, and 3-letter constellation abbreviation.
Other Objects: I have also added to full.rtg some of the brighter objects from the Abell catalog of planetary nebulae, and a few miscellaneous objects of interest. Also included are selected objects from the the Arp catalog of peculiar galaxies, many of which are already in the NGC, IC, or Messier catalogs. In a few cases, it was necessary to stuff the Arp number in the same field as the NGC number, following it. I have also added all clusters in the Globular Cluster Database compiled by Brian A. Skiff of Lowell Observatory, 15 globulars in the Palomar list (search for Pal 1, etc.), and 91 Quasars brighter than magnitude 15. Recently added were 109 bright Carbon stars, stars that are seen to be a deep red color. Both Quasars and Carbon Stars are now supported by the Search Wizard in Ver. 8.5.
Ignoring Invalid Catalog Entries: The Messier catalog, the updated NGC catalog, and most especially the updated IC catalog, contain many invalid entries. These objects may be stars miscataloged as deep-sky objects, or may be entirely nonexistent (the updated IC catalog contains about 2,000 objects that simply do not exist). RTGUI will default to ignoring these invalid entries, so that you will not be troubled by having inappropriate objects popping up during your searches. If you wish to change that option, click the Options button to bring up the Options Form, which contains your scope and Com Port selection. On it is a check box for ignoring invalid entries; set it however you wish. Even if the "ignore" option is selected, you can still access an invalid entry if you enter its primary name as your search name (so that no confusion arises over questions like, "Whatever happened to NGC 7326?") For example, M40 is an invalid entry in the Messier catalog. Assuming that the "ignore" option is set, it will not turn up on searches for M (all Messier objects), or for objects in Ursa Major. However, if you search directly for M40, you will find it.
Radio Objects:Also included in this package is RADIO.RTG, a list of the 233 "brightest" celestial radio sources. (Since nearly all radio telescopes have alt-azimuth mountings, amateur radio astronomers will find RTGUI to be very useful!)
RTGUI catalogs are in ASCII text form. If you are unsure of what they contain, you can examine them. It is not recommended that you use an editor to modify or add items to the catalog, because if the data is not properly encoded, or if the location of the fields on the line should change, search errors may result. RTGUI will add catalog items for you, after you type in the parameters, or download them from your telescope. Click the "Object" button. You may use an editor to remove unwanted or erroneous items added to a catalog, so long as you can delete the line CLEANLY, leaving no spurious characters behind.
Asteroids and Comets: Unfortunately, RTGUI can no longer automatically load Asteroid and Comet positions from the Minor Planet Center at Harvard, which no longer accepts ephemeris requests from third-party software such as RTGUI. Instead, you must create a Transient Catalog for the selected object. If you want to see a list of asteroids and comets that are currently visible, click on Visible Comets/Asteroids on the form that comes up when yhou click the "Get Comet/Asteroid" button. This brings up a browser page containing links to websites containing that information. When you have selected an object, you can create a Transient File for it using the process described here: http://transient.rtgui.com/. This is not complicated, it mostly involves cut-and-paste. Each Transient Catalog contains a list of positions for a single object, a comet or asteroid. The first name field for each catalog entry contains an hourly position for that object, coded with a particular time expressed in UT (GMT). When Transient Catalogs are loaded, the proper entry for the time set in RTGUI is automatically loaded; the catalog cannot be searched. The second name field will be the "official" name of the object, as received from the Minor Planet Center. If that name is longer than 12 characters, only the rightmost 12 characters will be displayed. All of the usual RTGUI functions such as Goto and Skymap can be utilized. When RTGUI detects a Transient file to be obsolete (its latest time position is earlier than the present time), that file is automatically deleted.
RTGUI automatically loads the position for the object at the nearest hour, and like other objects it is foillowed in real-time for as long as desired. The next hour's position is automatically loaded when necessary. Each subsequent time that you request the same object, the positions are loaded from the Transient Catalog you created. This allows you to go out to a remote observing site with no internet connection, yet easily take with you the positions of as many comets and asteroids that you wish to observe. After 90 days have elapsed, if you still want to observe the object, you can go to the internet to get another 90 days' worth of data. Once downloaded, you can locate asteroids and comets in non-real time, so long as you do not go outside the time frame of the downloaded positions.
When specifying a Comet or Asteroid, you must use the official designation for that object, as it appears in the Minor Planet database. Comet names must begin with C/ for Comet (Example: C/2002 T7), or P/ for Periodic Comet (Example: P/Halley). Asteroid names may be given alone (Example: Vesta), or preceeded by its official number in parentheses (Example: (4179) Toutatis). Any "diacritical marks" (example: an umlaut) in the name must be ignored. Certain alternate designations are accepted for cases where no internationally-accepted name has yet been given (for example, 2004 FX31; for more information, refer to the Minor Planet Ephemeris Service User Documentation. Also see the website Minor Planet & Comet Ephemeris Center at Harvard.. In some cases, the MPE database may accept a comet name entered without C/ (Example: 2006 VZ13). In this case, RTGUI will label the object an "asteroid." All asteroid and comet positions downloaded are geocentric (as would be seen from the center of the earth).
Because the Minor Planet & Comet Ephemeris database is case-sensitive, all comet and asteroid names entered are reformatted by RTGUI into formats that have been found to work. For asteroids, the initial letter is set to uppercase, the remaining letters all lowercase. For Comets, the initial C/ or P/ is capitalized, as is the letter following the year. However, there are some objects that have not yet received official designations, or for whatever reason whose names are unusual and may not be properly reformatted. In those cases, a name encased in "quotes" will be treated as a literal, and sent to the Minor Planet center exactly as typed. For example, VESTA is reformatted into Vesta, which is accepted. However, "VESTA" is not reformatted and is not accepted. Literals should be used only when problems are encountered with a name not being accepted; try variant captializations, spaces, inclusion or omission of numbers, parentheses, etc.
[Obsolete, in current release: There is the special case of "near-earth objects" (normally these are asteroids, although it is possible that there might someday be a "near-earth comet"). It is especially interesting to try to spot the fast-moving asteroid as it whizzes by the earth. However, in these cases hourly positions are too widely-spaced to easily locate the fast-moving object! Therefore a special type of "fast transient" file has been created containing object positions for each minute. When the "near-earth object" box is downloaded, 1440 positions are downloaded, as before. However, now they cover a peroid of only 24 hours. RTGUI automatically updates the position once each minute. This "near earth" option should only be used for objects approaching closer than about 0.10 AU (9 million miles / 15 million KM) to the earth, or having an apparent motion of more than about 5" of arc per minute. NASA maintains a current list of objects closely approaching the earth, which is accessible from RTGUI's Comet/Asteroid Page Unlike standard transient files, near-earth positions may be downloaded for non-real times. Whatever time is set in the program will be sent to the server as the start time for the positions. This time should not be more than a few weeks at the most from real-time to ensure accurate positions. This enables you to plan your observations for the night or nights when the object will be closest to earth. The start time of the positions of near-earth objects is encoded into the file name, which differentiates the files for different nights. ]
Auxiliary Catalogs: These are standard-format catalogs containing data of interest for advanced observers, for special observing projects, or for research. They are not included in the RTGUI+S zip file, because some of them are very large and the casual observer will not need them. These and other Catalogs can be downloaded separately from the main page at http://www.rtgui.com, from RTGUI on "groups.io", or from the hyperlinks below:
Messier Marathon Catalog (MARATHON.ZIP) : Once a year, in mid to late March, is it possible to see all 110 Messier objects in a single night's marathon observing session. This catalog contains all of the Messier objects, in the order that you need to observe them. Just search for "M", and keep hitting "next"! (Make sure that you are using the version of this catalog dated Aug. 2005 or later, so that the two invalid entries will not be flagged as invalid, and hence ignored.) Download is just 3k, 11k unzipped.
Washington Double Star Catalog Revised Oct. 9, 2004 to include constellation names for every object. Complete WDS 2001 catalog, 84,468 entries. Contains virtually every visual double star known. Don't waste those moonlit nights - observe thousands of double stars! In addition to the Constellation Names, I have cross-indexed the WDS with the HR and PPM catalogs, picking up Bayer (Gam Vir) and Flamsteed (61 Cyg) designations, as well as SAO numbers, where available. (Entries in the original WDS catalog contain only the WDS designation, and the DM numbers, so it's hardly user-friendly.) Separation and magnitude of companion are given, where available. I know of no other catalog of double stars so complete yet easy to search. For more information about this catalog, see http://ad.usno.navy.mil/wds.
Positions and Proper Motions Catalog (PPM.ZIP): ( 9.4 Meg download, 46.7 Meg unzipped. 468,861 entries). Updated Oct. 21, 2004 with additional data. Contains all SAO catalog objects, also has PPM numbers, & HD numbers, now cross-referenced with data in the Bright Star catalog. Every entry now has a constellation name. ( For information on the PPM, see http://heasarc.gsfc.nasa.gov/W3Browse/star-catalog/ppm.html ). .
General Catalog of Variable Stars (GCVS.ZIP):38,624 entries. 825k download, 4 Meg unzipped. . The standard reference catalog for variable stars. (For information on this catalog, see ftp://ftp.sai.msu.su/pub/groups/cluster/gcvs/gcvs/iii/ ).
General Catalog of Photometric Data (GCPD.ZIP): Catalog of stars used in photometric research projects. 152,000 entries. 2.2 meg download, 15.5 meg unzipped. Stars can be found by their 10-digit LID number, or DM or HD number (if listed in the catalog). For more information about this catalog, see ftp://cdsarc.u-strasbg.fr/pub/cats/II/167 , and click on "intro".
Catalogue of Quasars and Active Nuclei (quasars.zip), by Marie-Paule Veron-Cetty and Philippe Veron13,214 entries. 271k download, 1.4 Meg unzipped. . Complete list of known quasars as of March, 2000. (For information on this catalog, see http://www.obs-hp.fr/www/catalogues/veron2_9/veron2_9.html ).
Herschel 400 Catalog (HERSCHEL400.ZIP): 400 entries.9k download, 42k unzipped. The Astronomical League offers a certificate for those who observe the "top 400" objects from the Herschel list. For information, see http://www.astroleague.org/al/obsclubs/herschel/hers400.html .
Adding Objects to Catalogs: Click the "Object" button. You can enter the Right Ascension and Declination of any object directly, or its current Altitude and Azimuth. (The RA and DEC need not be current positions - any Epoch from 1900 to 2200 will do.) If you have a Meade Goto scope, or a Celestron Goto scope of Scope Type 1, you can read the position of the object being observed directly from it. You can add these objects to a catalog by using the "Add" button. You may also read objects from one catalog, and write them to another. You may also create your own catalog, entering object names and positions from the keyboard. This has the advantage of keeping your own user objects separate from full.rtg, which is likely to change in the future. If you do not want to keep changing catalogs when you observe your private objects, you can easily concatenate the two files. Just open up a DOS box, go to the directory where RTGUI resides, and type exactly this: copy full.rtg+my.rtg full.rtg . The result will be that your file named my.rtg will be added to the end of full.rtg. When entering the name of a catalog to RTGUI, you may specify any catalog epoch from 1900 to 2200. If you do not specify a catalog epoch, it will default to epoch 2000.
Skychart (Cartes du Ciel): Skychart is a popular, full-featured Open Source astronomy program that produces wonderfully detailed and accurate maps of the sky - and it is absolutely free. When RTGUI starts, it looks to see if Skychart is installed on your PC. (Everyone interested in astronomy should install Skychart!) If it is installed, whenever an object is selected, a button appears that will start Skychart if it is not already running, and transfer to it all the data about the current time, location, and selected object. The result will be an instant sky chart centered on the object you have selected, to help you identify it. RTGUI sets a reasonable initial width of the field in Skychart, depending on the brightness of the object you have selected. The brighter the object, the wider the field that is initially set. For very faint objects, the field will be very narrow. Of course, you can zoom in or out after that. It is recommended that the Skychart option "Use System Time" (in Preferences/Date-Time) be checked. Otherwise, RTGUI will change to Daylight Time when Windows does, but Skychart will not, and the chart you generate will not match the actual sky. If you change any Skychart options while using RTGUI, you should save them to disk or the changes may not be present in the next chart. It is recommended that you use the Skychart "telrad" option under the "show mark" button so that there will be concentric circles to mark the object's position.
Starting with Ver. 9.0, RTGUI supports Skychart Ver 3. You must use Skychart version 3.2x (10 Oct. 2010) or later. You can download it here. Also Skychart Ver 3.4x does not work with RTGUI. The current version of Skychart is 4.2, which is recommended.
Loading the location from a hand-held GPS Device: RTGUI can set the system time and the location from a hand-held GPS device. You must have a serial cable that connects the computer to your specific GPS device (for example, a Garmin GPS unit cannot utilize a cable from Magellan, and vice-versa). This will not be the same cable that you use to connect RTGUI to your telescope. Your GPS device must be configured to send data using the NMEA 0183 Version 2.0 data standard. This is a data format that is supported by virtually all GPS devices now being sold. If you do not know what data interface your GPS is using, the chances are that it is not set up for NMEA, as the default is likely to be something else. Consult the manual for your GPS to find out how to configure it to send NMEA data.
To select or change the COM port used with the GPS, click the "Options" button, then click "Select COM Port for GPS," and choose one of the available ports that are displayed. Your selection is recorded if you click the "Save" button afterward, or choose "Yes" when asked to save configuration changes when you exit the program. The operation of the two ports are completely independent, and neither interferes with the other. You can, however, use the same port for both, but then you must disconnect the telescope to use the GPS. When your GPS device is connected to the COM port that you have chosen for the GPS, turn it on. It is best to wait until the GPS has already obtained a good reading of your present position. Press the "Load" button. You will see a check box to determine whether to load time and location from the GPS, or just the location. The default is to load both. Next click "Load From GPS". RTGUI+S first displays "no valid NMEA data yet seen". If it still does not find any after about a minute, your GPS device may possibly have the wrong data configuration, may not have the correct cable, or the cable may not be properly connected. As soon as some valid NMEA data is seen, RTGUI+S displays "Waiting for valid satellite data fix". When this is seen, RTGUI is receiving correct NMEA data from the GPS, but the GPS is not yet indicating that it has valid position data. RTGUI will accept the first valid data record it sees containing your latitude, longitude, and the time. It will not average multiple readings. However, your GPS device may do such averaging, and will probably give you better accuracy with time. (This makes no difference in actual practice, as even an "inaccurate" GPS reading will be within about 250 feet, or 80 meters. An "accurate" reading may improve on that by a factor of ten.) When a valid GPS reading is obtained, RTGUI+S will display the minutes of your latitude and longitude to four decimal places, as opposed to the usual single decimal place. (For Goto purposes these small differences will have no practical effect.) If you "save" this position, the GPS accuracy will be retained the next time that you start the program. Most GPS devices display the estimated accuracy of the position it has obtained. If you are concerned about getting the most accurate reading possible, wait until the GPS displays the degree of accuracy that you hope to obtain, and then load it into the PC.
When a valid GPS reading is obtained, RTGUI will set the system time in Windows, using the UT date and time reading from the GPS device (unless you have unchecked the box to allow RTGUI to do this). While the time obtained from the GPS satellites is highly accurate, because of data communication delays owing to the slow 4800 baud rate of NMEA data, as well as processing delays, the system time set cannot be so accurate. RTGUI attempts to compensate for typical processing delays; the resulting time set in your PC is usually accurate to about one second. GPS readings can only be taken when RTGUI is operating in real-time mode. If the century is incorrectly set in your Windows system, valid time settings cannot be made, because only a two-digit year is received from the satellites.
Loading the location from a Celestron GPS or Meade Telescope: If your Celestron telescope is equipped with a GPS unit (including the CN-16), RTGUI can read from it the location, and optionally set the system time. Click Load, then Load from Celestron. This operation utilizes the same telescope data cable that controls the Goto operation. This yields the same accuracy as a hand-held GPS device. The location (and optionally, the system time) can be read from any Meade LX-200, LX-90 or Autostar telescope, whether it has a GPS or not. If the data has been entered manually in the telescope, care should be taken to ensure that it is correct. Click Load, then Load from Meade.
Recording Observations: You can easily take notes on the objects you observe. The Observing Log button will enable you write to a text file named rtguilog.txt. The first time the log is opened, it will automatically record the date, local time, GMT, and location, as well as the GOTO telescope type. Each time you open the log for a new object, it automatically records the object's names and magnitude from the catalog, its current elevation, as well as the local time and date. This saves you the trouble of entering this information yourself. An input box is opened for you to record your observations. Press "enter" when you reach the end of the line. You may enter as many lines as you like, until you enter a blank line, which returns you to the main menu. RTGUI does not have a full editor for the observing log, and it is not able to display or change a line after you have entered it. If you wish to add more notes before moving on to the next object, you may click the button again; this time the object name and the time will not be repeated. After your observing session is completed, rtguilog.txt may be edited or examined using any standard word processor such as Word or text editor such as Notepad. The information may be copied onto the Windows clipboard and pasted into other files or other programs if desired. It is probably a good idea to start each major observing session with a fresh copy of rtguilog.txt, all of the observations previously entered having been moved to some more permanent location.
Finding Solar System Objects: These are not, of course, loaded from catalogs (nor may their position be saved in one). RTGUI contains the orbital elements for each of the major planets, as well as for the moon. By selecting a "Planet" from the scrolling list, you may obtain the current RA, DEC, Altitude, and Azimuth for any of the seven major visible planets, Pluto the dwarf planet, the sun, or the moon, at whatever time and location is currently specified. Additionally, for each solar system object other than the sun the difference in ecliptic longitude is given between that object and the sun. For example, if the elongation of Venus is given as "40 Degrees Morning", then that object can be seen in the morning sky, 40 degrees west of the sun, as measured along the ecliptic. Asteroids and Comets also display their elongation, but it may not be along the ecliptic; for example, a comet might be 30 degrees from the sun, but pass due north or south of it, making it difficult or impossible to see. For the moon, the phase is given: for example, "LAST QTR." Also given is the distance to the object in Astronomical Units (AUs, the mean distance from the earth to the sun); the Moon's distance is given in kms. The apparent size of the planet is given in seconds of arc; the apparent size of the sun and moon, being much larger, is given in minutes of arc. For each solar system object, its constellation position is calculated and displayed. If the time or location is changed, information about the object being tracked will be updated accordingly.
Solar system objects are "tracked" in real time, exactly like objects from catalogs, and their position in their orbit is continuously updated, although this is scarcely necessary. Because many second-order factors are ignored, the positions of solar system objects are not as precise as an ephemeris program, although they are more than accurate enough for "goto" purposes. The use of new Basic-language planetary algorithms published by Keith Burnett has resulted in greatly improved accuracy over those used in my earlier MS-DOS program RT. The position error for the Sun and the major planets is typically around 1 minute of arc, and is seldom more than 5. The geocentric position of the moon (as seen from the center of the earth) is calculated internally to an accuracy of about four minutes of arc. This is then converted to a topocentric position, based upon the observer's actual position on the globe. Some astronomy programs do not make this correction. Without this correction, the calculated position of the moon is frequently a degree away from where the moon is actually seen in the sky. The topocentric position displayed should be accurate to within a few minutes of arc, bringing your scope right near the center of the lunar disk. The moon is the only object close enough that its topocentric position differs appreciably from its geocentric one, so the planets' apparent positions are not adjusted for the observer's latitude and longitude. The time of the moon's rise, transit, and set are not calculated exactly, but are approximated using assumptions of uniform lunar motion (when the moon rises, it is in a very different position than when it is on the meridian, or when it sets). If the greatest accuracy is desired, set the program's time to the value indicated for moon rise or set, at which point the displayed rise or set time should be quite good.
Trace Object: This feature is new in Ver. 9.2. The Trace Object button creates and displays a text file containing the altitude and azimuth of the current object for a selected number of hours, at a specified interval in minutes. The purpose of the trace is to make it easier to find objects when using telescopes on alt-azimuth mounts. You can print out a trace file for an object you plan to observe and take it out to the field, if you do not plan to bring a computer. The trace begins sat whatever time is set in the program, whether that is real time or not. A trace may run from 1 to 24 hours, at intervals from 1 minute to 60. After the trace is completed, the program time is returned to whatever time was selected previously, or to real-time, if RTGUI was previously in real time mode.
Color Options: The default background color of the screen is red, which is more conducive to maintaining dark-adapted vision. You also have the option to operate in black-and-white. Click on the title line at the very top to change the color. When you have a red background, there is a check box option for "night vision" operation. When "night vision" is selected, not only does the window containing RTGUI switch to much darker colors, but so does every other active application, typically to a very deep red background. This allows you to look at many different applications without losing your dark adaption. If a bright desktop behind the active window is a problem, you can maximize the RTGUI+S window by clicking the middle button at the top right of the Windows frame. This will fill your screen with lot of empty space of a very dark color. When RTGUI exits, the original Windows color scheme is automatically restored.
Precessing Object Positions: The coordinates are given for the epoch of the current year. If you wish to adjust these to some other epoch, you can change the date to any epoch from 1980 to 2199. The object's coordinates will automatically be precessed forward or backward to that epoch. You can then instantly return to real-time mode by clicking on the real-time button.
A check box exists on the Options form to ignore the effects of precession, and always use Epoch 2000. Because some Goto telescopes do not incorporate the effects of precession, in some cases you will get better results using a Fixed Epoch. The initial settings are: use Fixed Epoch for Celestron telescopes, otherwise not. However, you should try both settings to determine which will give you better results. The Fixed Epoch option actually allows you to use any year from 1900 to 2200 as your epoch. If you choose, you can have all positions automatically precessed to the year 1975, or 2025. Click on the Use Epoch XXXX label to change the year.Unless the Use Epoch box is checked, all items tracked are adjusted for precession to the current year. During the first half of the year, objects are adjusted to January 1 of the current year; after July 1, objects are adjusted to January 1 of the following year. Thus, the positions of objects will be more accurate than in any static catalog. If you load an object from a catalog of one epoch, then add it to a catalog of a different epoch, precession to the appropriate epoch will automatically be performed. The precession algorithm utilized is fairly accurate, typically within a few seconds of arc of the results of the "Rigorous Precession" program published in Sky and Telescope magazine in October, 1991.
Adjustments for Refraction: In addition to making adjustments for precession, the program automatically adjusts for atmospheric refraction, which causes objects low in the sky to appear slightly higher than their actual positions. An object on the horizon appears to be lifted a full half-degree above its actual position; this falls off rapidly as the object rises. Thus, an object becomes visible when it is actually about a half-degree below the horizon, because of atmospheric refraction. When the Right Ascension and Declination of an object are entered either from a catalog, or from the keyboard, the resulting altitude is automatically increased by the appropriate amount for refraction. Thus, an object less than a half-degree below the horizon will be given an altitude greater than zero.
When an observed altitude and azimuth are entered, the same adjustment is made in the opposite direction, decreasing the object's apparent altitude to its true altitude, from which its R.A. and Dec are computed. When an object is invisible, atmospheric refraction is ignored. Thus, when you are tracking a rising object in real-time, it jumps immediately from -0 degrees, 34.9 minutes, to 0 degrees, 0 minutes, indicating that it has just become visible to an observer at sea level with an unobstructed horizon view. As an object sets, it also instantly transitions from 0 degrees observed altitude to -34.9 minutes true altitude.
Some minor daily fluctuations occur in refraction, owing to changes in meteorological conditions. Also, as you go higher in altitude, the horizon appears to recede slightly. Thus, an observer at high elevations may be able to see objects which are a little below the horizon at sea level. Neither of these factors is allowed for in the program. Ignoring the slight effects of elevation above sea level and temperature and pressure changes, all objects having zero or positive altitude are potentially observable, and all objects having negative altitude are invisible.
Converting Alt, Az to RA, Dec: When you run across interesting objects in the sky, you can obtain their R.A. and Dec. if you know the altitude and azimuth. Just click on the Object button to start the process. This will enable you to identify what you have found (and to easily come back to it later). Just enter the observed altitude and azimuth from a Dobsonian telescope's "circles", and RTGUI, knowing the current sidereal time, will perform the inverse of the alt-azimuth function, and give you the R.A. and Declination of the object. This enables you to consult your star charts to determine what you are seeing. You can add the object to the catalog, if you choose.
Radio Astronomy Objects RTGUI can be used by amateur radio astronomers (there are a few!) to locate radio objects for observation. The catalog RADIO.RTG contains the IAU Commission 24 Working Group list of the 233 "brightest" radio objects in the sky, north of declination ??.
Scripting for Automated Operation: Starting with Ver. 5, RTGUI is now RTGUI+S, and accepts command-line parameters for certain functions. This allows scripts to be written for completely automated operation of telescopes, for observing or research projects using cameras or other instruments (see the document Scripting using RTGUI+S.). Because Windows has capabilities to run command files at various times, you can create script files to perform automated tasks at designated times. RTGUI also has commands to perform certain tasks at certain times. Usually the reason for writing such a script is to automatically position the telescope.
RTGUI+S can perform the following Command-Line Functions (which must be entered exactly as shown in these examples ). Each command must be terminated with a semicolon when other commands follow it.
cat=marathon.rtg /* changes catalog. If this command is used, it should precede "find" */
find=m81 /* finds an object in the current catalog */
match=next /* finds next matching object in catalog */
minalt=35 /* specifies a minimum altitude for matching objects */
minmag=11 /* specifies a minimum magnitude for matching objects */
name2=virgo /* specifies a second name that objects must match during search*/
planet=8 /* finds Neptune. (0=Sun, 1=Mercury, 2=Venus, 3= the moon, 4=Mars, etc.)*/
2000ra=03h14.55m, dec=+14d03.2m /* selects position in terms of RA and Dec for a given epoch*/
Alt=30d00m, Az=270d00m /* selects position in terms of Altitude and Azimuth at the present time*/
wait=03:30:00 /* RTGUI waits until the specified time to perform the next command */
date=23 /* if "date" precedes "wait", then the next command is performed when time and date both match */
sleep=10 /* number of seconds to 'sleep' before performing next command. Decimals OK. */
exit=04:30 /* will exit if the time is this value, or later */
command=4 /* acts as a "goto" for commands, sets up command processing loop */
shell=CameraControl P1 P2 /* Causes the execution of some other program, and passes it parameters. */
goto=ok /*authorizes telescope to Goto currently-selected object or position*/
stay=ok /* tells RTGUI+S to stay resident when command processing is finished - otherwise it terminates.
If "stay" is used it must be the very last command. */
An example of a command file using the above commands might be:
cd \astro\rtgui
rtgui cat=ppm.rtg; find=SAO12345; goto=ok
When RTGUI is given Command Line parameters and finishes performing them, it exits. If any command is invalid or fails for any reason, RTGUI exits immediately. All commands, successful or not, are written to the Observing Log (rtguilog.txt) along with their status upon completion.
The above is just a summary of how to use the scripting capabilities of RTGUI. For a complete description, see the document Scripting using RTGUI+S.
Troubleshooting Common Problems:
Connection Problems: Be certain that you are selecting the correct COM port on the Options selection form (click the Options button). If you are using a USB-to-serial adapter, these usually create COM ports in the range of 5-8. If Bluetooth software is installed, your virtual serial port may be 15 or more. If RTGUI does not list one or more COM ports that you think ought to be there, either the port is not properly installed, or else it is in use. Only ports that can successfully be "opened" are listed. Many large astronomy programs require you to "connect to telescope". If you are using a program that does that, it requires sole access to the COM port, and cannot share it with RTGUI or anything else. To see the status of the COM ports on PC, check MyComputer/ControlPanel/System/DeviceManager/Ports . If the Device Manager reports a problem with a serial port, you must resolve that problem first before the port can be used.
On the Celestron scopes, make sure that you are using the programming cable that connects to the bottom of the hand controller. Michael Swanson has some excellent information about Celestron connection issues in the PC Control section of his Nexstar Resource Site.
Donations Accepted: The use of RTGUI is free to all noncommercial users. However, if you feel that you have received significant value from it, you may want to make a donation to the author to support the development of this and other software, especially when you consider how many commercial astronomy programs sell for $50, $100, or more. The "donations" button near the top of this file allows you to make a contribution from your Paypal account or from a major credit card, in any amount.
Please report to me any comments you might have on RTGUI, or any problems you may find with it.
Robert Sheaffer
Lakeside, California
Check your Computer Clock: Before you begin a night's observing, the time in your system clock should be set accurately. The successful calculation of alt-azimuth positions (and hence, object visibility) requires that the time be accurately set. Because the "Goto" slewing is performed using RA and DEC instead of alt-az, it is less susceptible to small inaccuracies in timekeeping or in location so long as your telescope alignment is accurate. RTGUI will adjust for Daylight Savings Time automatically whenever your Windows system does. Make sure that the time zone and DST option are set correctly in Windows.
Updating RTGUI: You should check for updates periodically at www.rtgui.com , as future releases are likely to contain important updates and new features. The What's New page will keep you informed of updates. The full catalog should always be updated to the newest version, as new features are sometimes implemented (such as using 5 names), new objects are added, and any errors noted are fixed. It usually is not necessary to unpack a new home location file rtgui.hom, saving you the trouble of re-entering your latitude, longitude, and telescope data. When RTGUI detects that it is using a .hom file that was created by an earlier version of the program, upon exit it prompts you to save that file even if no changes have been made, to ensure that all data is stored in an up-to-date format.
Searching for Stars: While the constellation names for deep-sky objects in FULL.RTG are fully spelled out up to 12 letters (so that star name do not turn up in searches for deep sky objects), for stars three-letter constellation abbreviations are used. The rules for finding star names in the catalogs are:
A. Common name (in FULL.RTG only): Just type MERAK. You can also truncate the name, so long as there are enough letters to be unique. If the string is not unique, the search will return the first match that it finds.
B. Bayer (Greek letter) Designation and Flamsteed
Number(in FULL, WDS, PPM): Some examples are:
Bet UMa
You do not need to worry about case, or the number of spaces
between characters in the name. If you are not sure whether a star name contains
a number designation between the Greek letter and the constellation name, use
the wild card character *. The new Search Wizard will formulate the correct
syntax for finding stars by Bayer or Flamsteed designations.
Xi Gem
Omi2 CMa
Xi 2 Sgr
61 Cyg
C. Yale Bright Star Catalog Number:
HR 2491
D. SAO Numbers (for most stars in the Yale Bright Star
catalog, and some in PPM, WDS)
SAO 184415
Many of the fainter stars can be found only by these designations.
Abbreviations used for the Greek letters in star designations are as follows: Alp,Bet,Gam,Del,Eps,Zet,Eta,The,Iot,Kap,Lam,Mu ,Nu ,Xi ,Omi, Pi ,Rho,Sig,Tau,Ups,Phi,Chi,Psi,Ome. In some cases there is a number following the letter designation, i.e. Alp2.
Abbreviations for the constellations in star designations are as follows: Aql,And,Ant,Aps,Ara,Ari,Aur,Aqr,Boo, Cae,Cam,Cap,Car,Cas,Cen,Cep,Cet,Cha,Cir,CMa,CMi,Cnc,Col,Com, CrA,CrB,Crt,Cru,Crv,CVn,Cyg,Del,Dor,Dra,Equ,Eri,For,Gem,Gru,Her,Hor, Hya,Hyi,Ind,Lac,Leo,Lep,Lib,LMi,Lup,Lyn,Lyr,Men,Mic,Mon,Mus, Nor,Oct,Oph,Ori,Pav,Peg,Per,Phe,Pic,PsA,Psc,Pup,Pyx,Ret, Sco,Scl,Sct,Ser,Sex,Sge,Sgr,Tau,Tel,TrA,Tri,Tuc, UMa,UMi,Vel,Vir,Vol,Vul.
otes:
1. RTGUI is a 32-bit program for Windows systems such as Windows XP, Windows 7/8/10, etc.. It is written using Microsoft Visual Basic 6. RTGUI spends 90% or more of its time suspended in the background. It awakens every 900 ms to update astronomical data, or when a function is requested.
The Application Program Interface used to access the COM port is taken from
"modCOMM" published on TheScarms by David M. Hitchner (see
RTGUI is based upon an earlier MS-DOS program, "RTASTRO" (RT.EXE). RTASTRO is still available for Windows 3.1 and DOS users at http://www.debunker.com/astro/rt_702.zip. It has many of the features of RTGUI+S, but without the easy-to-use interface. The accuracy of its planetary and lunar positions is not nearly as good as RTGUI, and it does not have the catalog updates. It is no longer being supported.
2. Starting with Release 3, RTGUI+S uses a proprietary catalog format, described below. The Messier and Radio catalogs came originally from the 1987 version of "The Floppy Almanac", with positions set to Epoch 2000. The Naval Observatory replaced its original Floppy Almanac program with the freeware program Interactive Computer Ephemeris (ICE). It has since replaced ICE with MICA, the Mulityear Interactive Computer Almanac, which costs $24.95.
3. RTGUI does not read status from any telescope during GOTO operations. It only writes the current object's RA and DEC to the control port, using the data format proper for that scope's protocol. But this is good - there have been situations when this code, because of its total simplicity, has worked and certain expensive, heavily-advertised astronomy programs would not! Do not attempt to "goto" an object when the telescope is already in motion, or when the scope is not properly aligned. RTGUI relies on your own common sense rather than on complicated handshaking with the telescope to control the GOTO operations.
4. NGC and IC Object Updates in RTGUI:
With Release 7, RTGUI now offers in its default catalog FULL.RTG fully-updated data on NGC and IC objects that is far more accurate and up-to-date than the standard NGC, RNGC, or NGC/IC 2000, which contain many errors. The NGC / IC revisions for RTGUI were carried out using available on-line catalogs such as the NGC/IC Project, SIMBAD, NED, etc. Those catalogs can be accessed here: http://www.seds.org/~spider/ngc/ngc.cgi?1 .
Many objects in the NGC and IC catalogs are listed as “unidentified”, or have the wrong object type. (For example, supposedly there are many “bright nebulae” in Coma Berenices: of course, those objects are galaxies). The NGC/IC Project has recently completed its first-pass revision through the NGC (but not yet the IC),identifying (or dropping) missing objects, resolving duplicate ones, correcting incorrect object types, etc. As for the IC catalog , most observers have no idea what bad shape it is in. A full 44% of the IC objects are cataloged as “unidentified” or unknown, and many of those having object types are incorrect. Most objects lack magnitude information. Without this information, the observer has no idea whether an object (assuming it even exists) is magnitude 11 and visible in medium-sized scopes, or magnitude 16 and not visible except in the largest amateur instruments. Many objects are multiply-listed, the same object appearing more than once in the NGC and/or IC catalogs under different designations, and often at incorrect positions.
The goals of my NGC / IC updates were:
Galaxies, where appropriate, now include the following additional search terms (where noted in SIMBAD, NGC/IC Project, or elsewhere): cluster, group, pair, triplet, quartet, Seyfert, dwarf, LowSurfaceBrightness, and interacting. Galaxies that are double can be recognized by the term “Galaxy: 2”. Many irregular or disturbed galaxies can be found by searching for the designation Arp (a catalog of irregular galaxies), or the term “peculiar”. Those observers having large “light buckets” (becoming far more common these days) would do well to select galaxies flagged as “cluster”, “group”, “trio”, “quartet”, etc., to see how many faint fuzzies they might pull in. The labels “group”, “cluster”, etc are given only once, for the brightest member of that association. Each individual member of a “group” is not so labeled.
The results of the updates are shown in the tables below:
|
Object Classification |
NGC 2000 |
RTGUI Updated |
|
Unidentified/Unknown |
166 |
0 |
|
Nonexistent |
- - - - - |
17 |
|
Galaxy |
6032 |
6063 |
|
Bright Nebula |
102 |
109 |
|
Open Cluster |
530 |
652 |
|
Cluster + Nebula |
127 |
95 |
|
Planetary |
97 |
98 |
|
Globular |
151 |
139 |
|
Star (single) |
62 |
38 |
|
Star (double) |
50 |
23 |
|
Star (triple) |
22 |
9 |
|
Asterism / > 3 Stars |
20 |
9 |
|
Object Classification |
IC 2000 |
RTGUI Updated |
|
Unidentified/Unknown |
2379 |
0 |
|
Nonexistent |
- - - - - |
1208 |
|
Galaxy |
2650 |
3437 |
|
Bright Nebula |
98 |
79 |
|
Open Cluster |
60 |
38 |
|
Cluster + Nebula |
9 |
9 |
|
Planetary |
37 |
35 |
|
Globular |
2 |
7 |
|
Star (single) |
97 |
119 |
|
Star (double) |
41 |
67 |
|
Star (triple) |
10 |
21 |
|
Asterism / > 3 Stars |
2 |
14 |
|
Total Objects |
5383 |
5053 |
The number of objects does not remain constant because many objects appear in one or both catalogs more than once, and this has been resolved. The biggest “winners” in the NGC revisions were the Open Clusters, increasing from 530 to 652. The number of galaxies increased by 31. The net effect of the IC revisions is to increase the number of unique deep-sky objects (excluding nonexistent objects, asterisms, etc.) from 2856 to 3605, mostly by adding 787 “new” galaxies (while “losing” misidentified nebulae and open clusters). Many supposedly unique IC objects were “lost” as duplications of objects in the NGC list.
The updates are particularly significant for southern observers, because the catalogs were in worse shape for far-southern objects. One result is that the constellation Pavo is now seen to be extremely rich in galaxies, with many in groups or clusters.
Caveats:
1. Not all of these NGC / IC updates were performed in a fully systematic manner, and are not appropriate as a foundation for scholarly research. In all cases, the on-line catalogs must be considered definitive, not the RTGUI version. The purpose of each update was simply to answer the question, “is there a deep-sky object here that can be seen in a telescope?”
2. Most IC entries that appeared to be correct and complete were not updated, especially for the fainter objects. It is possible that some of them may still have incorrect object types, or positions. Not all object magnitudes have been updated with more recent data. However, the brighter IC objects (about mag 12 or brighter) have all, or nearly all, been updated. If you examine FULL.RTG using a text editor, objects having magnitudes specified to two decimal places have not been updated from the original catalog information.
3. Most of RTGUI’s NGC positions are still using epoch 1975, which does not matter so long as the original position is correct, since RTGUI automatically precesses all positions of catalog objects to the current year. All updated object positions are specified as Epoch 2000.
4. Most NGC objects that are erroneous or invalid are simply missing from FULL.RTG. If an NGC number is missing, it is because the number does not correspond to an actual deep-sky object, as recorded in the NGC/IC Project . However, invalid objects in the IC catalog were retained for reference purposes, as other sources will still list many of them.
If you are aware of any inaccuracies or problems in my NGC / IC revisions, please let me know. My goal is to offer the most accurate deep-sky object list possible for astronomical observers.
5. Known Problems: Changes made to code to read location from Meade scope, attempting to address a problem reported with the new RCX400 scopes (apparently a small change in scopes' responses). Issue not yet resolved.
Problems have been reported with the Goto on the Meade Autostar model 494, which has more limited real-time capabilities than the other Autostar models. A 5 ms delay has been inserted between each character to attempt to remedy this problem. In addition, there is a 50 ms delay between the commands. However, the problem is not yet resolved.
6. How To Construct Alt-Azimuth "Setting Circles": (This does not apply to electronic telescope-pointing systems, such as are now being installed on many Dobsonian scopes (example: Orion's "Intelliscope Controller"). If you have that, you don't need Alt-Azimuth circles. Set Scope Type = 5 (managed by Skychart), to implement a two-step Goto process.
With RTGUI it is possible for users of telescopes on alt-azimuth mountings to find objects using a different kind of setting circle: altitude and azimuth circles, aligned only to the earth's gravitational and magnetic fields, respectively. As an added advantage, you do not need to spend time carefully aligning to Polaris or anything else, as the earth's gravitational field can give you your altitude, and the earth's magnetic field can give you your azimuth. While your friends are struggling with their polar alignments, you can be pulling in various deep-sky objects!!
Install a gravity-based device for measuring elevation (a goniometer) somewhere on your telescope tube, or in a convenient spot on your mount. Originally this was just a weighted needle pointing downward from the center of a protractor, which enables you to directly read the angle of elevation of your tube, but nowadays you can buy a digital version of this tool, which is much more accurate and easy to use. The California-based retailer Harbor Freight has been selling them for about $30.
Your azimuth circle will be a magnetic compass, the best you can find, with degrees of azimuth clearly marked on the outside ring. An electronic compass with a digital readout can also be used. Install it on some convenient spot on your mount, where it remains level. Make sure that there is NO metal anywhere near it, not even nails or screws.
Next, run RTGUI+S, and be certain that your latitude and longitude are correctly set as the default in your "home" file. Stay in real-time mode, and find "POLARIS". (It scarcely moves in the sky, thus it is good for calibrating circles). While looking at Polaris in your telescope (or some other convenient star), carefully adjust the azimuth circle on your compass, or the compass itself, until it reads what RTGUI says it should read, and fix it in this positions. This does not have to be done each time you observe, but only once, unless your circles are disturbed.
You are now ready to begin finding objects with your Alt-Azimuth setting circles. Be careful to keep your magnetic compass away from large metal objects, or other magnets.
7. The format of the data in the catalogs is as follows:
Catalog Format starting with RTGUI+S Version 3.0 (extension "RTG")
Field Field Contents Units Example
position format
1-12 A12 Name1, left justified --- Alp2 Lib (see notes A, B)
13-24 A12 Name2, " --- Libra
25-36 A12 Name3, " --- Galaxy
37-48 A12 Name4, " --- NGC 650
49-60 A12 Name5, " --- ZubenElGenub
61-69 F9.6 RA hours 14.84791
70-79 F9.6 DEC degrees -16.04180
81-87 A7 Unused
88 A1 Catalog Format - "T" indicates Transient Catalog with hourly positions
"t" indicates Transient Catalog with minute-by-minute positions
"D" indicates Catalog of Double Stars
"G" indicates Catalog of Galaxies
"L" indicates Catalog of Globular Clusters
"O" indicates Catalog of Open Clusters
"P" indicates Catalog of Planetary Nebulae
"Q" indicates Catalog of Quasars
"N" indicates Catalog of Bright or Dark Nebulae
"M" indicates Catalog of Mixed Deep-Sky Objects
"S" indicates Catalog containing named stars
"R" indicates Catalog containing Radio Astronomy objects
"F" indicates Full (default) Catalog
89-96 F8.4 Visual Mag / Radio flux in Janskys 2.9000 (see note C)
97-100 F4.0 Epoch of Coordinates year 2000
Notes:
A. If the first character of Name1 is an exclamation point (!), the entry is treated
as a scripting command, and not as a catalog entry. Only the "Planet=" scripting command
is supported as a catalog entry at present. If the first character of a name is an equal
sign (=), it is not displayed but prevents that name from being matched in searches. This
ensures that searches for small-numbered NGC objects will not return larger-numbered objects first.
B. If the last two characters of Name1 are a double-carat (^^) or ampersand-carat (&^),
that designates that the entry is to be included in "Best of the Sky". The special
characters are not displayed.
C. If the magnitude of the object is not known, this field should be set to 99, which
will display as "Unknown." A blank field will be interpreted as Magnitude 0, which
is an extremely bright object, and the object will turn up in inappropriate searches.
If you created any catalogs using the old ".CAT" format (Release 2 or earlier, also shared by RTASTRO), the small program cat2rtg.exe will read a catalog in the old format and write it out in the new one.
The small utility addconst.exe can be used to add constellation names to objects in new catalogs to enable searches by constellation.The utility addlabel.exe can be used to add labels to new catalogs to make them usable with the new Search Wizard.