
   			Using Transient Catalogs with RTGUI+S - Jan. 22, 2007.

	Transient catalogs are created for non-fixed objects of unusual interest, typically a bright comet, or perhaps an asteroid. Because these objects are rapidly moving about our solar system, they cannot be placed in the "fixed" catalogs, along with stars and Messier objects.

	Version 8 of RTGUI now has the capability to create Transient Catalogs automatically and
 effortlessly - all you do is give it the name of the object. Therefore, you do not need to use
"ephtortg". However, there may be a small number 
of users who have a proxy connection to the internet, or have access problems with a firewall, 
and cannot use that new functionality. Those users must make Transient Catalogs for comets and 
asteroids the old way (which only takes a few minutes, anyway). Remember that it is perfectly possible 
to download transient catalogs to one computer, and copy them to another (they should be in the 
TransientCats directory below the RTGUI program directory).

	Each transient catalog contains only object, and the name of the file should tell you what the object is, and when the positions are good. In a transient catalog, the first name is always the TIME of the position, in numeric format: Month, Date, Hour (UT), Year. For example, May 10 23:00 UT 2004 is represented 05 10 23 2004 (remember that spaces are ignored by RTGUI searches). Entries are compiled at hourly intervals. The remaining name fields will give additional information about the object, however as they will be identical for each entry.

	RTGUI automatically loads the proper entry from a transient catalog, based upon the UT (GMT) set in the program. This happens as soon as the transient catalog is loaded (click on the "catalog" display line to change catalogs). Thus a transient catalog cannot be searched. The entry is re-checked periodically, and as time passes RTGUI+S will switch to the next hour's entry when that one becomes the best fit. If the time or date is changed by clicking on the time or date field, the proper entry for the new time will automatically be loaded. If the transient file does not contain a position appropriate to the time set in the program, an error box is displayed, and no object position is loaded.  

	Assuming that you have SkyCharts (Cartes du Ciel) installed, you can use the "SkyChart" button to see a star map showing the transient object. To mark the object's position, use Cartes du Ciel's red 'eyepiece circles' ("Show Eyepiece"), which gives you a little bull's-eye at the object's position (but be careful - if you move the map in CdC, the eyepiece circle moves, too).

	- Robert Sheaffer


			Creating your own Transient Catalogs:

	You may create your own RTGUI+S transient catalog for any object whose ephemeris is available through the Minor Planet & Comet Ephemeris Service at Harvard, 
		http://cfa-www.harvard.edu/iau/MPEph/MPEph.html .  But don't use that URL.

	The web page http://www.debunker.com/astro/transient.html has been created to facilitate getting data from the Minor Planet center, in the proper format for RTGUI+S. To obtain current positions, you need only specify the name of the object you are interested in. Note that the name *is* case-sensitive, and generally it seems to like capital letters (Example: C/2004 Q2). This gets you 60 days' worth of data, in hourly format. You can also get 60 days worth of data starting at some future time, by specifying a starting time, in the format specified on the page. Then click "Get Ephemerides".

	The resulting data is to be cut-and-pasted into a text file, using Notepad or an equivalent text editor. You can name it whatever you choose. Do not use a file name longer than 8 characters at this point, and the extension must be ".txt" . You don't even have to carefully cut around the edges of the actual data - the conversion program will do that for you. Just "Control-A, Control-C" will do fine for grabbing the data, "Control-V" to paste it somewhere. . You need to download the little conversion program ephtortg.exe (Version 3 or later is recommended) from http://www.debunker.com/astro/ephtortg.exe . Version 3 will add the constellation name for each object position to Name5. 

	The conversion program must run in the same directory as the text file you created. It will ask you for the file name to be converted, and also for Name2, Name3, and Name4 for your object. You can enter whatever you wish for these names, or leave them blank. It is best to supply informative names, such as the object's official designation, as well as its popular name. After the .RTG file has been created, you can rename it to whatever longer name you wish. 