[Aavso-photometry] Opinion needed

[Jim Roe]

arne wrote:
> 
> Some possibilities:
> 
> The parent star crossing a bright pixel on your CCD that is not properly
> calibrated out.  This can happen if your field is drifting on the CCD.
> 

I think this is the explanation.  My scope is not perfectly aligned on 
the pole, so there is some drifting across the field. Upon aligning and 
animating the images to look for a possible asteroid (none found and the 
MPC has no record of one brighter than mag 20 within 15 arc min), I 
noticed some residual hot pixels that weren't removed with the usual 
dark frame adjustment.


Also noted that the effect got "wider" with increasing aperture size 
which would be consistent with drifting across a fixed hot pixel (also 
an asteroid).

Overall, an interesting, and useful, object lesson.

Jim Roe [ROE]