Re: GSC 3493-1324

[Michael Sallman <msallman@pro-ns.net>]

Sebastian and all,

I do try to "flag" observations that are potentially "bad", mainly for
calculating the Welch-Stetson statistics.

What I have been doing is this:
Michael R.'s pipeline provides statistics for each image. These
statistics are described at
http://spiff.rit.edu/tass/pipeline/pipeline-latest/pipeline.html
They are:
# image file name
# filter
# Julian Date of exposure
# exposure time (seconds)
# image type: "dark", "object", or "flat"
# Right Ascension
# Declination
# sky value
# skysig value
# average Full Width at Half Maximum (FWHM) for frame, in pixels
# number of stars in image
# photometric zeropoint
# photometric color term, which will be the same for all images in some
passband for a run
# "include" flag: if 1, keep processing this image; if 0, ignore it

If any of the statistics (sky value, skysig, FWHM, zeropoint or color
term) for an image are more than 3 sigma away from the mean for all the
images from that particular camera (there are 6 cameras, 3 pairs of V &
I), I flag the image, and all the observations from that image. That was
the most objective method I was able to come up with. And it seems to
work reasonably well. Currently, there are 8,061,637 observations
"flagged" in this manner.

Mike

Sebastian Otero wrote:
> Dear Michael,
> 
> This is an EA with a period of 7.6540 days and secondary at phase 0.485
> (slightly eccentric). NSVS data are available to check these stars. I attach
> a plot with the lightcurve.
> Tom, here is my concern regarding false "eclipses" one stumbles upon in TASS
> data. I can throw datapoints away from the other databases looking at the
> flags or rejecting discrepant points made in pairs just  seconds apart. But
> with TASS data I don't have any indication in the file I download. There are
> three points at JD 2453109 that are wrong and I would have used them as a
> true eclipse if only analysing TASS data. They seem consistent with each
> other but they are not.
> Isn't there a way to flag these observations?
> 
> Best wishes,
> Sebastian.
> 
> 
> 
>>Patrick Wils, it appears that the period you came up with on this star
>>is broken now that TASS got some more data. It also doesn't work with
>>the data I got the last couple of nights. In two nights I got one that
>>showed no variation over 5 hours and one that showed a 0.4 mag drop in
>>V over 2.5 hours. I almost got the ToM but clouds moved in. I tried
>>using AVE and Fourier to find a new period to no avail. One could make
>>an educated guess of the ToM from my data as 2453160.7287. That puts
>>the ToM's, in a very loose way, at the following:
>>
>>2452758.7857
>>2452781.7331
>>2452785.7228
>>2453109.8470
>>2453160.7287
>>
>>FYI, I'm doing simultaneous V and Rc. The period is long enough on this
>>(and clear skies rare enough) that I would be appreciative if anyone
>>wanted to grab V data until we figure this guy out. It appears to be a
>>detached system and it is possible, even probable, that we have a
>>flat-bottomed eclipse.
>>
>>Target    : GSC 3493-1324
>>Target RA : 15 58 18.66
>>Target Dec: +48 14 47.55
>>V=11
>>
>>Comp Star : GSC 3493-1212
>>Comp RA   : 15 58 40.516
>>Comp Dec  : +48 12 21.15
>>V=12.3
>>
>>Comp Star : GSC 3493-1088
>>Comp RA   : 15 57 29.096
>>Comp Dec  : +48 19 24.64
>>V=11.9
>>
>>Cheers,
>>Michael Koppelman
>>
>>On Jun 2, 2004, at 6:15 PM, Michael Koppelman wrote:
>>
>>
>>>GSC 3493-1324 looks like a good prospect:
>>>
>>>http://wiki.tass-survey.org/tass/view.do?
>>>nodeId=Tass&contentId=TassJ155818.6%2b481448
>>>
>>>Not a known variable that I can determine. Not referenced in NASA ADS.
>>>Doesn't show up in Google except on TASS pages.
>>>
>>>I will probably start in V so if anyone wants to do B, Rc or Ic, let
>>>me know.
>>>
>>>
>>> ------------------------------------------------------------------------
>>>