"Funny thing" example in DS23

[Patrick Wils <patrickwils@yahoo.com>]

--- Tom Droege <tdroege2@earthlink.net> wrote:
> 5) There are plenty of funny things in the data.  One has to look at
> the 
> raw fits files and tie the funny things into what was happening in
> the 
> image.  There are lots of things to investigate here.  WS finds
> things 
> where V and I are varying together that are obviously not star 
> variations.  One just has to study data to understand what is going
> on.

Here is a funny thing from DS23 (from the file Mhra2295674.cal).  It
concerns the star GSC 0747-1324 (nothing special about this in VizieR
as far as I can tell).  The output of wsv3.pl for this star is
(observations from 3 nights):

 42722  141  141 102.1059   7.9550 11.40  0.03 10.28  0.01  35.396

However, the high WS statistic (35.396) is caused only by the following
line from collected.big:

 42722 141 102.1057 7.9531 2452296.69392 V 10.795 0.016 0 I  8.703
0.003 0

Ic is 1.5 mag brighter than average, V 0.6 mag, and also the position
is 7" south of the average, and well outside all other positions, which
lie in a circle with a diameter of about 2".  Removing this single
line, reduces WS to 0.567, not variable at all.

Because this anomalous object is visible in both V and I, I suspect it
is not a cosmic ray effect.  If it is caused by a satellite glint, it
should be a high object (low satellites are not in sunlight close to
local midnight in January), but I think it is too red for a satellite
(I am not sure on this, probably others have more experience).  Maybe
element sets for this date and/or the raw images may spread some light
on this.

There are other objects in DS23 for which there is an anomalous
observation (a lot brighter or fainter than the average), but I haven't
found one for which the position is anomalous as well (but I haven't
looked very hard).

Patrick



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