"Wow, I think I've discovered a new variable star! But how can I be sure?"
You can find one good summary of steps to take in the MISAO Project's guide to investigating interesting objects. Read on for some other suggestions.
If you find an interesting object in some TASS catalog or in the database itself, you should first check to see if someone else has already noticed it. Arne Henden (in a message to vsnet-chat on 16 Jan 2001) suggested taking the following steps:
John Greaves wrote a guide to searching for asteroids in TASS data included on Data Set 23; it gives very detailed instructions for using the "Guide" star charting program.
read the guide to using "Guide" to search for asteroids
Arne's paper on surveys (text, PDF)
Arne's paper on surveys (slides, PDF)
If, at this point, your object still appears to be a new variable of some sort, then
SIMBAD stands for Set of Identifications, Measurements, and Bibliography for Astronomical Data. It is a giant database which collects in one place millions of measurements from the astronomical literature, focusing mainly on stellar sources (for extragalatic data, see NED). SIMBAD contains several different services, but the one of interest is its ability to search for all known information about a star near some particular position.
There are two main WWW sites, one on each side of the Atlantic:
You will need to register to use SIMBAD, but there is no fee for most European or American users. Just read the registration information at http://cdsweb.u-strasbg.fr/simbad/userid.html and then fill out the appropriate form. You may need to wait a day or so for your registration information to be processed.
The examples below have links to the US mirror site; European users should follow the instructions and ignore the links.
Once you've registered, you can quickly look up information on any particular star of interest. The normal approach is to select the Query by identifier, coordinates or bibcode item on the main SIMBAD page. It presents a form which looks in part like this:
You must enter the coordinates of the object in question into the box at top left. Of the many possible formats, two make the most sense for TASS-related queries:
03.4239 +01.2363It's important to have at least 2 digits to the left of the decimal point (use leading zeroes if necessary), and required to have either a "+" or "-" sign in front of the Dec value. Do not use a comma between the RA and Dec numbers.
12 34 56.7 -03 45 67Once again, make sure to include the "+" or "-" sign in front of the Dec value.
After you submit a query, SIMBAD should return a form with a list of the objects it has found in a small area centered on your coordinates. It always lists the positions of its objects in HHMMSS.ss DDMMSS format, which can be a pain if you only know the coordinates in decimal degrees. I believe that the object closest to the given position is always listed first in the output. You can learn more about any of the listed objects by clicking on its name in the list.
If no object appears close the position you specified, then SIMBAD's catalogs don't include it. Even if an object does appear at the position of your candidate, it may be listed as a humdrum, ordinary star.
On the main TASS WWW site, there's an item labelled Sample data and variables:
There are two similar pages on the TASS Wiki which lists variables (new, old and suspected) in a format which is easier to search:
These pages have examples of stars which TASS members have noticed in their examination of our data. There are some examples of new variables, and some re-discoveries of known ones. Unfortunately, we haven't listed in any uniform manner the name or position of these variables, so it may be difficult to verify that your object is or isn't among the set listed here.
Martin Nicholson has gathered together candidates for variable stars in the TASS database, from several different sources. You can find his lists here: