Position from SIMBAD
RA, Dec (J2000) 00 13 43.349 +06 56 18.18
Patrick Wils, 2002 November 28
HD932 (star numbered 1317 in the file): John mentioned this already before, presenting it as a delta Cep, with a period of 10.3 days. My guess is that it is an RRc with a period of 0.322 days or an alias thereof. This agrees with the A5 spectrum. Someone should go out and observe this star to solve this.
Chris Llody, 2002 November 29
Using data John sent me for HD932 and two near-by stars I've done differential photometry and can confirm what everyone believed, that it is variable - probably a W UMa (again), with P=2/(n.1), with n small. In fact there are only a few likely periods so a couple long runs should crack it. It is still well placed to observe. In the process I have discovered that the differential photometry is really quite good. The two comparison stars I used were GSC 00008-00599 (#1309) and GSC 00008-00313 (#1251) which according to Tycho-2 have delta V=0.34+/-0.036 (se) while TASS gives 0.320+/-0.002 (se). The standard deviation of the TASS delta V is 0.022 while Tycho is near 0.3. I guess this has been mentioned before but one of the limits on the TASS photometry is the relatively poor Tycho photometry used for calibration.
Shawn D, 2002 November 29
I've got nearly hours of data on HD932 so far tonight. It showed a nice, linear drop of 0.27 mag over the 3.5 hours, and it's just starting to bottom out now. I'll follow it another hour or so if the cirrus clouds don't get thicker. Assuming this is an EW then the period has got to be at least 0.6d (4*3.5hrs). Using Mike Sallman's nice web page it looks like TASS saw a range of about 0.4 mag V. Again, if this is an EW, and I'm observing a primary (or the minima are very nearly the same depth), then from tonight's data the quarter-phase interval is more like 6 hours, and the period is thus about 1.0d. Once I finish collecting data tonight I'll get it reduced and send it to the list. If it's a pulsating star then divide by 2.
Chris Lloyd, 2002 November 30
That sounds quite possible - with n=2 in my previous post you get P~0.95 days. If you observe it again soon you will probably pick up the same eclipse so I guess it'll be another 10 days or so before the other half of the cycle becomes properly observable.
Arne Henden, 2002 Dec 1
I had little confidence in John's classification as "Cepheid" since the colors are very blue (V-I=0.35) for a 10-day variable. I think the present thinking of an EB is much more likely. Nonetheless, I am surprised that Tycho was not able to obtain a period/classification for such a bright object.
Shawn D, 2002 Dec 6
Here's the data I gathered on 11/29 for HD932. A V filter was used with a CB245 on an LX200-10". Each point is an average of three 60s exposures. The internal error reported by sextractor is <0.01mag, and the standard error from the three-point averages is also <0.01. The gaps occurred when the scattered clouds became too thick and the data got too noisy. The graph shows the nice, smooth curve which reached a minimum (using AVE) at HJD = 2452608.6482 +/- 0.0003. To my non-professional eye it looks like an EB, but we need to see more of the curve to have a better idea. Given that the period looks to be around 1 day (darn it), I didn't collect any data on 11/30, and it's been somewhat cloudy here for the past few days. Hopefully this storm that's brushing us, and dumping lots of snow and ice up north, will pass by tomorrow so I can collect some additional data.
Shawn D, 11 Dec 2002
Scattered cirrus is plaguing me tonight, but it's the best weather we've had in over a week (and this is our dry season!) so I went ahead and started collecting more data on HD932. I caught the tail end of a descending branch and am now watching it climb slowly back to maximum. The minimum from 11/29 was at delta v = 0.02 and tonight's is about 0.06 so at first glance it looks like an eclipser with about a 1 day period. However I still have to subtract the dark frame and apply a flat to this raw data, so this small 0.04 mag difference may evaporate. ToM occurred at approx. 00:40 UT.