[vsnet-chat 1105] Re: [vsnet 1499] Larry Robinson's SN1998dh image

[Yamaoka Hitoshi <yamaoka@rc.kyushu-u.ac.jp>]

Dear SN watchers,

Larry Robinson wrote:

> Object        Date    U.T.     R.A.  (2000.0)  Decl.   Mag.   Observer
>SN1998dh     1998 08 02.26876  23 14 37.23 +04 32 19.5  13.2 V Sunflower
>Observ

This magnitude is quite brighter than other estimates.  He wrote he
have used Astrometrica and USNO-SA as reference stars, but it is
uncertain which stars are choosed as a photometry reference.  

I have seen the image
(http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/SNe/sn1998dh/robinson.jpg)
which seems to me that SN 1998dh was about 14.0 mag or so, comparing
with 1306 and 1456 stars (USNO-A1.0).  

Is this a problem of reference stars or of a software?

Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp

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