[vsnet-chat 1116] (fwd) Larry Robinson's SN1998dh image

[Taichi Kato <tkato>]

Date: Tue, 04 Aug 1998 19:28:08 -0500
To: vsnet-chat@kusastro.kyoto-u.ac.jp
From: Larry <lrobinsn@ix.netcom.com>
Cc: rhaler@lymax.com
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Subject: [vsnet-chat 0] Re: [vsnet 1499] Larry Robinson's SN1998dh image
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>Date: Tue, 04 Aug 1998 19:26:23 -0500
>To: Yamaoka Hitoshi <yamaoka@rc.kyushu-u.ac.jp>
>From: Larry <lrobinsn@ix.netcom.com>
>Subject: Re: [vsnet 1499] Larry Robinson's SN1998dh image

I redid my measurements using Astrometrica and my 60 sec image and the
following data is recorded using different reference stars in the image than
before:

OBJECT                  RA                  DEC              D      MAG
DMAG
SA 0900.3310336  23 14 32.65   +04 35 30.8  +1.1  13.69   -0.11
SA 0900.3311229  23 14 59.02   +04 33 48.1  -0.5   13.88   -0.32
SA 0900.3308707  23 13 48.10   +04 36 18.9  -0.4   12.71  +0.11
SA 0900.3310824  23 14 47.47   +04 38 14.3 -0.3   14.26   +0.46
Object                    23 14 43.72   +04 32 06.7           13.20

MEAN RESIDUALS:  DRA = 7.54
                                 DDEC=0.56
                                 DMAG=0.25MAG

So what am I doing wrong.  I get the same answer.  Any suggestions from this
data?  Any knowledgeable comment is welcome.  I am still learning.  Please
help me.

Larry



>At 01:16 PM 8/3/98 +0900, you wrote:
>>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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