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About the SkyTools Imaging Databases
#1
Hello,

I have had several inquiries lately from people who were looking for specific catalogs in SkyTools 4. So I wanted to take a moment to explain how the SkyTools databases are built.

SkyTools doesn't merely open raw catalogs like the most other software. Raw catalogs are full of errors, and they are often limited in some way. I have built databases for each type of object from multiple catalogs, taking the best data available from each. One catalog may have the best positions, another may have better magnitude, size or other data. So there is no one catalog that you can look for in SkyTools. If you ask me if the Gagawagno catalog is in SkyTools, I can't give you a definitive answer. All I can do is assure you that the best of the Gagawagno will be there in the database, and say whether or not there are Gagawagno cross references available.

Once a database is built for, say, Supernova Remnants, or Planetary Nebulae, the next step is to create cross reference databases. Each object may be known by a common name, or NGC number, but they may also be known by more obscure designations from other catalogs. The majority of objects only have these obscure designations. A great deal of effort has been made to create complete cross references for designations from the major catalogs that amateurs use.

As an example, the following cross references are available for galaxies: Common name, Messier, NGC, IC, Arp, Markarian, MCG, UGC, UGCA, RFGC, ESO, Z, Heschel, PCG and LEDA.

So how do you access these catalogs? It is important to realize that the target lists for the Target Selection Tool are not themselves catalogs, even though some are called Messier or Caldwell. These are in fact just lists of targets. There are several ways to make your own:

1. Use the Database Power Search Tool. Access this via the "Get Target Lists" menu of the Target Selection Tool. This is a very sophisticated search engine that can make you many different kinds of target lists. For instance, you could search the 1.5-million galaxy database for only very thin galaxies, list the most distant quasars in Virgo, or make a list of Cubewano minor planets.

2. Press the "Add Objects" button. This opens the Designation Search dialog. This dialog is used to look up specific objects. For most objects you can simply enter a designation and press Search. But notice that there is also a Browse tab. Sometimes a designation is not formatted in a way that SkyTools can recognize, although a lot of effort has been put into recognizing different formats. But that does not mean the object isn't in the database.

For example, lets say you typed "MCG-1-1-13" (without a space). SkyTools may not recognize it, because in order to help it recognize the many different designations, it needs a space between "MCG" and the rest. You may also have inadvertently typed MGC. In the end, the galaxy is not found. If you open the Browse tab, select Galaxies, and then "MCG" as the catalog, all of the MCG galaxies will appear on the right. Note how the designations are formatted. This tells you to try putting in a space or reminds you that it is MCG. Yould could also scroll down to your object, or type part of the designation at the top to find it.

So what if you can't find an object at all? Try opening the Atlas. If you have coordinates, click in the upper left to open the Object Requestor, then select the "Enter Coordinates" tab. Type in the RA and Dec, press Accept to the right, and then Accept at the bottom. Does the object appear on the chart? Be sure to use the "Set" button under "Mag Limits" to set the magnitude limit for this type of object to very faint, and maybe zoom in closer. Ninety nine out of one hundred times the object will be right where you expect it to be. Put the cursor over it and open the Object Info. Note the designation you need to enter into SkyTools for this object.

If you can't find an object, or find an error, please let me know. I will work to update and fix the database or add the object to a Supplemental database.

I have spent more than 20 years developing these databases, using my training as a professional astronomer to get it right. Sadly, some my competitors have made some pretty outrageous claims about their own databases in an attempt to make them appear to be as comprehensive as SkyTools. They are not.
Clear skies,
Greg

SkyTools Developer
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