[vsnet-chat 4562] Re: Photometric problem using USNO-A2.0

[Seiichi Yoshida <comet@aerith.net>]

Dear Dr. Skiff,

> Subject: [vsnet-chat 4537] Re: Photometric problem using USNO-A2.0

>      You can make plate-by-plate zero-point corrections to USNO-A2.0 by
> making use of my large photometric reference file...
> 
> http://ftp.lowell.edu/pub/bas/starcats/loneos.phot

Thank you for your information on the catalog. 

Dr. Henden and Dr. Sumner sometimes provide sequences for photometry
of novae, bright supernovae, CVs, etc, to vsnet-sequence. Does the
list contains those data and has it kept being updated? 

Anyway, the list seems good for photometry. So I will support the list
by the PIXY System 2 in the near future. 

Well, we can also correct the zero-point using the Tycho-1 or Tycho-2
catalog, as discussed about one month ago. I guess the accuracy of
loneos.phot is better than the Tycho-1 or Tycho-2. But anyway, we can
determine the magnitude properly using some photomety-specified
catalog as reference. 

Actually, we corrected the zero-point using Tycho Catalog in case of
the example image in the MISAO Project activity. We did not report the
magnitude based on the USNO-A2.0 (R) except when there are only few
Tycho stars in the field.  The document is just an example to show the
bad accuracy of magnitude in USNO-A2.0 (R) for CCD observations.

Best regards,

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

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