[vsnet-chat 4324] Apogee AP-7p

[Seiichi Yoshida <comet@aerith.net>]

Dear colleagues,

I am Seiichi Yoshida working on the MISAO Project.

KenIchi Torii and Yusuke Ezaki offered their CCD images to the MISAO
Project. Their CCD chip is Apogee AP-7p.

I would like to measure the magnitude of stars in proper style of
photometry, as described at:

  http://vsnet.aerith.net/misao/pixy/tutorial/photometry.html 

But there is no coefficient k value of 

  Instrumental mag = V + k * (B-V) 

recorded in the Dr. Henden's paper on Apogee AP-7p chip.

So I tried to estimate the proper k value for the chip using the
Torii-san's images on 7 nights in 2000 July.

But the result became unexpected.

I plotted the k value obtained from each image on the chart:

  http://vsnet.aerith.net/tmp/torii.gif

We can see the evident systematic shift among the nights. 

Torii-san told me that there are some difference of condition among
the nights.

July 10		refractor
July 16		reflector
July 22		refractor + reducer
July 23		refractor + reducer
July 29		reflector + reducer
July 30		refractor + reducer
July 31		reflector + coma corrector

The reducer and coma corrector are some sorts of lenses. I do not know
they are common English words or words only used in Japan.

I have four questions.

1) Has anyone estimated the k value for Apogee AP-7p chip before?

2) Is it natural that the magnitude system of refractors and
   reflectors are so different, even using the same CCD chip?

3) If the difference among nights are due to the refractor/reflector
   difference, or the reducer and coma corrector, how do we have to
   mention the system in the VSNET format? Speaking of the new MISAO
   observations, I only record the CCD chip in the comment column. 

   But...

   3.1) Do we have to attach some special code after magnitude digits
        or some special comments for lens instruments, like refractors
        or camera lens?

   3.2) Do we have to attach some special code after magnitude digits
        or some special comments for informal filters, like reducers
        or coma correctors?

   For instance:

   MisVxxxx 20010401.12345 12.34C Mis KAF-1600+coma_corrector(refractor) - Ken'ichi_Torii

4) What is the difference between July 22/23 and 30? Torii-san used
   the same instruments on those nights. 

Best regards,

--
Seiichi Yoshida
comet@aerith.net
http://vsnet.aerith.net/

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