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[vsolj-alert 307] SN 1999by in NGC 2841



山岡@九大理 です。

加藤さんがすでにお知らせの通り、明るくなりそうな超新星が出現しています。
とりあえずvsnet-alertに出した情報です。

---
cf. vsnet-chat 1843
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chat/msg01843.html
cf. vsnet-chat 1844
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chat/msg01844.html
cf. vsnet-chat 1845
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chat/msg01845.html
cf. vsnet-chart 151
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chart/msg00151.html
cf. vsnet-obs 20407
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/obs20000/msg00407.html

Dear SN watchers,

  Following SNe 1999bw and 1999bx, the remarkable SN has discovered by
British amateur R. Arbour and LOSS KAIT team independently.  This new
object, named as Supernova 1999by, is in brightening phase, and will
potentially reach the brightness which can be easily caught by small 
(say, 5') telescopes. 

  IAUC 7156 tells that the position of SN 1999by is: R.A. =
9h21m52s.18, Decl. = +51o00'07".2 (by KAIT team), which is about 100"
west and 91" north from the core of the host Sb galaxy NGC 2841.  The
foreground stars near SN are there: 

                 R.A.      Decl.    offset from SN  mag(about)
GSC3431_625  9h21m50s.8 +51o00'36".5  12"W,29"N     11
GSC3431_053  9h21m47s.4 +50o58'50".3  45"W,78"S     13
GSC3431_495  9h21m58s.3 +51o00'15".8  58"E,8"N      14
unnamed(*)   9h21m54s.6 +51o00'16".9  23"E,10"N     17

(*) is potentially a condensation in NGC 2841.

  There seems some systematic errors in USNO magnitudes, and also in
GSC magnitudes.  The photometric (magnitude estimating) observer
should use the sequence kindly provided by Prof. Skiff (vsnet-alert
2917, 2919) for the comparison.  

  NGC 2814 has produced (at least) three supernovae in this century.
Among these three, only one, 1957A, was observed around its maximum at
B = 14.  It has been classified as a peculiar type I supernova.  Other
two had been missed their maximum.  

  NGC 2814 is about 0.7 mag nearer than Virgo center (M 87).  Thus the
typical SNeIa in this distance will have about 11.5 mag at their
maximum without absorption.  Now 1999by is in a rapidly brightening
phase, so the followup observations (includeing spectroscopy) are
extremely urged. 

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

From yamaoka Mon May  3 16:26:10 1999
Received: (from yamaoka@localhost)
	by rcsvr.rc.kyushu-u.ac.jp (8.8.8+2.7Wbeta7/3.7W/rc[99.03.09.00]) id QAA25422;
	Mon, 3 May 1999 16:25:58 +0900 (JST)
Date: Mon, 3 May 1999 16:25:58 +0900 (JST)
From: Hitoshi YAMAOKA <yamaoka>
Message-ID: <vsolj-alert307@hoge.baba.hajime.jp>
To: vsnet-chat@kusastro.kyoto-u.ac.jp, isn_chat@supernovae.net,
        vsnet-chart@kusastro.kyoto-u.ac.jp
Subject: Re: [vsnet-chart 151] Chart of SN1999by
Cc: yamaoka
Status: R

Re: [vsnet-chart 151] Chart of SN1999by

>      Was the BVRI sequence I sent out earlier not suitable for getting as
> better zero-point in the NGC 2841 field using USNO-A stars?

I have been compiled GSC and USNO mags for stars in Brian's list. 

Name         GSC          V    B-V   V-R   V-I  GSC_V   U_r  U_b
NGC 2841 1   3431-0219   8.48  1.29  0.67  1.23  8.20   8.1  0.0
NGC 2841 2   3431-0625  11.07  0.59  0.33  0.65 10.59  13.0 12.6
NGC 2841 3Ts 3431-0388  12.62  0.64 (0.37)      13.00  12.9 14.4
NGC 2841 3   3431-0053  13.51  0.75  0.43  0.83 13.32  13.3 15.2
NGC 2841 4   3431-0495  13.77  0.60  0.40  0.74 13.84   ---  ---
NGC 2841 5   3431-0159  14.19  0.83  0.42  0.91 13.97  14.0 16.1
NGC 2841 147 3431-0802  14.72  0.88             14.29  14.0 16.1

 (NGC 2841 4 is located well inside of the disk of NGC 2841, so USNO
catalog missed it.)

USNO mag seems not to gleatly differ except NGC 2841 2 star (it is on
the edge of NGC 2841), but I agree that observers should use Brian's
list as comparison.

Hitoshi

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