[Aavso-photometry] Comp star c in HMXB 1930+53 - CORRECTED

[Tim Crawford]

Gordon,

I did photomety on the d-c comps and measured the
Standard Deviation for three nights.  Sorry to have
taken so long on this but I was at Calgary also and we
drove home.

5/25/07

240 images  137 minutes  SD: .0074

5/31/07

360 images  209 minutes  SD: .0076

6/2/07

341 images  214 minutes  SD:  .0065

This data shows the C comp to be pretty "rock solid"
from this analysis.

Please Advise.

Ad Astra

Tim Crawford  CTX
Arch Cape Observatory


--- "Gordon E. Sarty" <gordon.sarty at usask.ca> wrote:

> To all HMXBers: Can you please check your check star
> data in the field 
> of the HMXB 1930+53. The comp star c at 19 32
> 44.543, 53 49 39.698 (see 
> chart at
>
http://www.usask.ca/psychology/sarty/Astronomy/LPH115_aavso.pdf
> 
> ) may be variable. See discussion with Ray Bloomer
> below.
> 
> Thanks
> Gord
> 
> -------- Original Message --------
> Subject: RE: CV Photometry
> Date: Sun, 01 Jul 2007 08:59:26 -0400
> From: Bloomer, Raymond <rhbloome at king.edu>
> To: Gordon E. Sarty <gordon.sarty at usask.ca>
> References:
>
<C15E4787A1495844951D08DAD6EBCAEF6D8398 at kingmail.king.edu>
> 
> <4685C731.9020403 at usask.ca>
> 
> Yes, C was the brightest of the comparison stars
> close to the variable.
> 
> Please do confirm with others.  As I said we had
> strange things going on 
> with the filter wheel. It seemed to have a mind of
> it own:  one morning 
> we leave with the filter certainly centered on the G
> filter, and then on 
> boot up the next night it is between two filters,
> vignetting big time. 
> WE eventually were careful to take the camera off at
> the beginning of 
> the evening and confirm it position.  So I suppose
> the 0.4 mag jump was 
> involved with that problem.  b and d did not show
> such a large jump, 
> more within the scatter of a few hundredths of 
> magnitude.
> 
> I'll be interested to hear what others have to say.
> Thanks,
> Ray
> 
> ________________________________
> 
> From: Gordon E. Sarty [mailto:gordon.sarty at usask.ca]
> Sent: Fri 6/29/2007 11:00 PM
> To: Bloomer, Raymond
> Subject: Re: CV Photometry
> 
> 
> 
> Phooey, so by "C" you mean the star at 19 32 44.543,
> 53 49 39.698? If
> so, everyone will have to revise their reductions.
> The stars b and d are
> very red but if they are stable we'll have to use
> them. I'll be at the
> AAVSO meeting this weekend and will ask around and
> see if anyone else
> has noticed that c is variable.
> 
> I've been awarded more DAO time - an AN should be
> released sometime soon.
> 
> Gord
> 
> Bloomer, Raymond wrote:
> > We had six full nights in May on LPH115 using the
> 41 CM and electrically
> > cooled CCD.  We had filter issues, but most of our
> data is in the green.
> >
> > We have not finished with the data but I think it
> seems clear that
> > comparison star "C" is variable.  Has anyone
> reported that?  We have
> > seen unexplained 0.4 mag jumps in differences that
> included C.
> >
> > My differences of b and d were reasonably well
> behaved (SdDev = 0.01 or
> > 0.02 mags).
> >
> > Ray
> >
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