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[vsolj-alert 202] SN 1998ef in UGC 646



山岡@九大理 です。

UGC 646に発見されたIa型超新星1998efですが、銀河の後退速度から見積もら
れた極大等級よりも発見時ですでに1等近く明るく、今後の動向が非常に注目
されます。

スペクトル観測から超新星なのは確実ですから、距離の推定が悪いのか、それ
とも本質的に明るいものなのか、予断を許しません。

現在15等級ほどですが、測光が可能な方は是非御注目ください。以下に、
vsnetに投げた情報を添付します。

			九州大学(六本松地区)理学部物理学教室  山岡  均
			〒810-8560 福岡市中央区六本松4-2-1
			yamaoka@rc.kyushu-u.ac.jp
----
From yamaoka Tue Oct 20 10:32:41 1998
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	Tue, 20 Oct 1998 10:32:40 +0900 (JST)
Date: Tue, 20 Oct 1998 10:32:40 +0900 (JST)
From: Hitoshi YAMAOKA <yamaoka>
Message-ID: <vsolj-alert202@hoge.baba.hajime.jp>
To: vsnet-obs@kusastro.kyoto-u.ac.jp
Subject: SN 1998ef early photometry
Cc: yamaoka
Status: R

SN1998ef early photometry

object    YYMMDD(UT)   mag  code
SN1998ef  981010.300  <180C KAI
SN1998ef  981014.300   167C KAI
SN1998ef  981018.300   152C KAI


From yamaoka Tue Oct 20 11:35:43 1998
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	Tue, 20 Oct 1998 11:35:42 +0900 (JST)
Date: Tue, 20 Oct 1998 11:35:42 +0900 (JST)
From: Hitoshi YAMAOKA <yamaoka>
Message-ID: <vsolj-alert202@hoge.baba.hajime.jp>
To: vsnet-chat@kusastro.kyoto-u.ac.jp, isn_chat@mbox.queen.it
Subject: SN 1998ef in UGC 646
Cc: yamaoka
Status: R

cf. vsnet-chat 1394
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chat/msg01394.html
cf. vsnet-chart 110
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chart/msg00110.html
cf. vsnet-obs 16833
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chat/msg16833.html

Dear SN watchers,

  According to IAUC 7032, KAIT team has discovered a supernova 1998ef.
It is located at R.A. = 1h03m26s.87, Decl. = +32o14'12".4 (2000.0),
which is about 6" east and 2" south from the nucleus of the host
barred-spiral(?) galaxy UGC 646.  The new star is well near to the
nucleus.  Spectroscopy has performed and it is determined that this SN
is of type Ia. 

  There are some confusing foreground stars: GSC 0228201278 (GSC mag =
13.75) is located about 17" west from the nucleus; USNO 1200-00446148
(USNO R = 15.3) is located about 21" east and 10" north from the
nucleus.  Finding chart based on USNO A1.0 are available at:
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chart/msg00110.html

  The host galaxy is rather further one.  Estimated with its recession
velocity, typical SNeIa on this galaxy would be expected to be 16.0
mag or so on their maximum (vsnet-chat 1394).  However, KAIT team has
reported that the magnitude at discovery (Oct. 18.3 UT) was 15.2 mag,
which is well brighter than expect.  It can be caused by the error of
the distance, but it is possible that this SN Ia 1998ef is
intrinsically bright one.  

>From the early photometry (vsnet-obs 16833), SN 1998ef seems to be
still on the stage of rapid brightening.  Further magnitude estimates
are highly encouraged.

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


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