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

[Gordon Sarty]

Thanks a whole bunch Tim - this is very valuable (assuming that there 
are no big jumps between nights).

I think Ray may be having some instrument trouble of some sort 
(saturation?).

So to the rest of the HMXBers: the comp "c" star for 1930+53 is 
functionally rock-solid and continue to use it.

I enjoyed your talk on intermediate polars in Calgary, Tim. Very nice.

Gord

Tim Crawford wrote:
> 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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