[Aavso-photometry] variable comp star in field of TT Ari?

[Richard Huziak]

Hi Jim, et al.

I managed to run on the field last night for about 2 hours.  There is no 
variation of the 11.1 star >0.020 during that time.  So if anything 
happened, it is over now.

Here are the three ensemble stars I used and returned average mag for 
the 11.1 over the 1st 22 frames of the run (~10 minutes):

Ens star value 1:  13.064V   Result average: 13.063V
Ens star value 2:  12.494V   Result average: 12.496V
Ens star value 3:  11.829V   Result average: 11.819V
*Target expected: 11.050V   Result average: 11.047V  *for the 111 star.

So everything seems OK in the field. 

rick HUZ

Jim Roe wrote:
> I started watching TT Ari on Sunday night, did a time series of some 280 
> points, reduced the data using the 111 (11.075) star close to TT Ari as 
> reference and everything looked fine.  The comp stars were nice and 
> repeatable so I uploaded the batch.
>
> Last night I again got a nice sequence, used the same reference star and 
> comps but, compared to the night before, both comps were nearly 0.2 mag 
> off from the night before.  As I suspected the reference star to be at 
> fault, I re-ran the images using a different reference star but added a 
> couple more comp stars and used the (previous) reference star as a comp. 
>   Here is a table showing the differences between Sunday night and 
> Monday night.
>
> delta(111) = 0.134 (0.04)
> delta(146) = -0.038 (0.053)
> delta(118) = -0.069 (0.011)
> delta(131) = -0.060 (0.016)
>
> Ref (on both sets of data) = 125(12.494).
>
> where the sense of the subtraction is Sunday result minus Monday result 
> and the star designations are from the TT Ari chart 071025.  It looks to 
> me like the 111(11.075) star brightened substantially in one day. 
> Comments, questions?
>
> Jim Roe [ROE]
> Wentzville, Missouri
>
>
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-- 

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Richard Huziak
Manufacturing Engineering
SED Systems
Saskatoon, SK, Canada
tel. (306) 933-1676
<huziak at SEDSystems.ca>
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