Re: Some variables from November's data set

[Tom Droege <tdroege2@earthlink.net>]

Patrick and all,

This is the fun of looking at raw data.

First, 0.2 mag is a dividing line.  More that 0.2 mag and it is probably 
real.  Less than 0.2 mag and it depends.

The effect I have been talking about tends to produce a variation in the 
data that looks like an arc.  Because some of the later data was taken 
sampling a half dozen times during the 16 minutes that it takes a star to 
transit the camera view, this tends to produce a period in any program that 
looks at time.  I would think it would be biased to periods of 1/2 hour or 
so or multiples.  However, 0.2 mag seems to be about the maximum for this 
effect.

I have looked at the HD932 data and am willing to take bets on the side 
that it is really a variable.  Beyond that, the period is up for grabs.

I am setting up now to start to take serious data.  The plan is to take one 
V, Ic measurement of as much sky as possible once a night.  I plan to 
devote 3 tass telescopes to this for the next ten years.  This will get 
long period data but it does not do much for short periods.

I then plan to build some Mark Vs.  This will be able to track the sky for 
longer periods.  I will run these tracking one or two fields for as long as 
possible each night.  I will not repeat these fields counting on tying in 
the Mark IV data.

Comments are welcome.  There does not seem to be a good strategy that I can 
implement on the Mark IVs.

Tom Droege

At 02:55 PM 11/28/02 -0800, you wrote:
>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.
>
>GSC 00613-01099 (7697): An EW with a period of 0.336 days (or an
>alias), mag 11.4-12.0V. B-V=0.59.
>
>GSC 00622-00482 (10814): Probably another EW ranging between 11.1 and
>11.5V. The period however is not that clear, because there are a lot of
>equally important alias frequencies. B-V=0.55.
>
>GSC 00008-00448 (1531): Also an EW ?  Mag 11.0-11.6V.  There is some
>scatter around the best period of 0.286 days. B-V=0.40.
>
>GSC 00594-00324 (124): This may be becoming dull, but it looks like
>another EW, but with a smaller amplitude 10.25-10.45V, period 0.318
>days (B-V=0.95).
>
>GSC 00621-00566 (10276): Mag 11.3-11.6V, EW again, B-V=1.15, period
>0.335 days ?
>
>I'm getting suspicious here.  All "best" frequencies of these stars
>seem to be near 5, 6 or 7 cycles per days (or in fact half of those
>values, because EWs have 2 cycles per period).  Is this some sort of
>selection effect, because of the way the data are sampled ?
>
>The spread on the couple of data points for most stars on JD ...561
>seem very high compared to other nights.  Maybe due to clouds ?
>
>Patrick
>
>
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