Re: HD932

["Rolling Hills Obs \(Shawn D\)" <rollinghillsobs@cfl.rr.com>]

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.

Shawn


----- Original Message -----
From: "Chris Lloyd" <cl@astro1.bnsc.rl.ac.uk>
To: <tass@listserv.wwa.com>
Sent: Friday, November 29, 2002 5:17 AM
Subject: HD932


> 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.
>
> I'll put some plots up somewhere - is it okay to post them to this list?
>
> Chris
>
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