Re: "Funny thing" example in DS23

[Tom Droege <tdroege2@earthlink.net>]

This is just the sort of thing that post processing can eliminate.  One 
could look at the WS statistic first, and then test all the high WS 
stars.  Look for points off the mean position, and then check their 
mags.  If position AND mag are off the mean, then this is probably 
justification for removing the measurement.

This is one of the things I wanted to test for some time ago.  I looked, 
but did not find very many measurements in this category.  So such 
measurements are probably rare.

Tom Droege

At 01:07 AM 7/8/02 -0700, you wrote:
>--- 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
>
>
>
>__________________________________________________
>Do You Yahoo!?
>Sign up for SBC Yahoo! Dial - First Month Free
>http://sbc.yahoo.com