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

[Jim Roe]

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