[vsnet-alert 3688] SN 1999eu in NGC 1097

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

cf: [vsnet-alert 3683] NGC 1097 BVRI sequence
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-alert/msg03683.html

Dear SN watchers,

  IAUC 7304 announced two SN discovery.  The host galaxies of these
two are apparently interacting galaxies, have recently produced other
SNe, and one of them is quite nearby, comparable with Virgo cluster.
In this article, I will write only about this nearer one.  

  The (probably) closer one, SN 1999eu, is discovered by a Japanese
amateur Masakatsu Aoki on Nov. 5 at 17.3 mag.  Its location is R.A. =
2h46m20s.79, Decl. = -30 19'06".1 (2000.0), which is 23" east and 157"
south of the center of SBb galaxy NGC 1097.  This new object lies on
the southern arm.  

  NGC 1097 is apparently interacting with small E galaxy NGC 1097A,
which locates about 3'.5 NW from the nucleus of NGC 1097.  Possibly
due to the interaction, NGC 1097 has many blobs in its arms.  Because
of these blobs, The GSC gives many spurious stars along the arms.  The
USNO catalog seems to give less spurious stars, but some exist.

  The CfA group has taken a spectrum of this SN on Nov. 8.3 UT, 
http://oir-www.harvard.edu/cfa/oir/Research/supernova/spectra/snngc1097.jpg
and it reveals that it is of peculiar type II.  The expansion velocity
is quite small (< 2000 km/s), but well-developed P-Cyg profile is
present unlike SNeIIn.  They suspect that it resembles to subluminous
SN 1997D.  

  The resession velocity of the host galaxy is about 1200 km/s, from
which its distance is expected to be comparable to the Virgo cluster.
The typical unobsecured SNeIa on this distance would become 12 mag
order.  SN 1992bd, another SN II produced by the same galaxy, was
observed at V = 15 though it seemed to be highly reddened.  SN 1999eu
may not become so bright, but it will give us a rare oppotunity of
observing such a subluminous event and an understanding of the nature
of peculiar SN II.  Followup observations are highly encouraged.

  Prof. Skiff has kindly provided the sequence near to NGC 1097 at 
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-alert/msg03683.html.
, which was taken from Hamuy & Maza (1989).  Note that they are quite
brighter than the reported magnitudes of SN 1999eu.  The nearest USNO
stars to the SNe are: 

     ID         rmag  bmag  offset from SN    note
U0525_00750214  17.6  19.8   43"E, 25"S
U0525-00750431  16.5  18.1   76"E, 58"N       east end of the bulge
U0525-00750310  16.6  17.7   59"E,109"S
U0525-00750202  17.4  20.3   41"E, 96"S
U0525_00750787  17.1  19.8  132"E, 59"S
U0525_00751172  13.1  14.7  192"E,101"S       

The last one is "NGC 1097 5" in Skiff's sequence (V = 13.71, B-V =
0.68, V-R = 0.40, V-I = 0.79).  The USNO rmag of this star is quite
close to R (13.31). For the moment, I guess that the CCD observers
can be use USNO rmag for comparison.

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

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