For the past few years I've self-published a book on variable stars seen in galaxy fields during the CRTS supernova search SNhunt. Recently updated to version 7. Added one previously unknown EW to it. Better phase plots for most of the periodic variables. With more images available through SNhunt that I could download and perform photometry I found that a number of stars I thought were variables apparently are not.
With Sebastian's recent e-mail I've started going back through my latest version. Where possible comparing ASAS-SN data with the CRTS data. Definitely have some questions to pose regarding some of the variables.
First off is SSS_J063847.2-201539 (=UCAC4 349-015218 at RA = 06 38 47.183, Dec = -20 15 39.22) which I've classified as probable EW with a possible period of 0.332072 day from the CRTS data, though there are definite problems with the phaseplot. However, that period does not work for the ASAS-SN data. The best fit is a RRc with a period of 0.248767 day. Doubling that period did not work well to see if it is an EW. Then trying those periods with the CRTS data does not work. Don't understand why this is the case. If it is the data or my doing something incorrectly. There is another 13th magnitude star some 24" east. I would think it would be far enough to not contaminate the data.
Please see attached phaseplots.
Thanks.
Stan
Hi Stan,
The periods you give are most probably 1-day aliases of each other and are very close to integer fractions of a day. Period searches based on data taken almost exactly 1, 2 or sevaral days apart, can be rather difficult then. You should take small enough steps between different test periods. 0.497506 d seems to be a good period that fits all data.
Patrick
Thanks, Patrick!
For stars such as SSS_J063847.2-201539 how should I proceed to update the data on VSX? As I look through my proof copy of V7 I find myself thinking it needs completely redone and add more information for each variable based on the submission guidelines. Also, I need to check a number uncertain variables to ASAS-SN data. That may take me another year to complete. As I think there is only one new periodic variable found (an EW) perhaps should I submit it on its own? The only other new variables are some for which I been unable to determine a period and a few probable in some nearby galaxies.
Looks like I may be a bit late for credit to the new W UMa found in SNhunt search and added to Verson 7.0 of the SNhunt variables. ASAS-SN just posted a paper regarding their new RR Lyrae variables https://arxiv.org/abs/1801.07716 with a link to their variables site https://asas-sn.osu.edu/variables. When I put in the coordinates the W UMa variable showed up. However, don't see anything in VSX yet or for the position at VizieR. The CRTS designation is CSS_J071713.3+670749 and I had come up with a period of 0.337626d (see attached image). ASAS-SN has 0.3376d. https://asas-sn.osu.edu/database/light_curves/6519. At least their data pretty much agree with what I had found in the CRTS data.