[vsnet-alert 3553] SNe 1999eb and 1999ec

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

Dear SN watchers,

  Two SNe has been discovered by LOSS KAIT team, both of which are
produced in galaxies who had produced other supernova(e) in recent
years.  

  For the first, SN 1999eb was found on Oct. 2.4 and confirmed on the
earlier images.  The location is R.A. = 1h43m45s.45, Decl. =
+4o13'25".9 (2000.0), which is about 5" west and 4" north from the
bright central core of the spiral galaxy NGC 664.  It is quite near
from the core, and overposed on the bulge region surrounded by faint
arms. 

  The reported magnitudes (unfilitered CCD) by discoverer are;

Sept. 13.4  >19.0
      19.4  :19.0
      22.4   18.0
      29.4   16.8
Oct.   2.4   16.2

It is pity that the earliest stage has been lost without observation,
but it seems to be still in the rising phase.  The spectroscopy has
revealed that it is of type IIn.  

  This galaxy had produced two other supernovae recently; SNe 1996bw
and 1997W.  These two could be seen at the same time (cf. IAUC 6551),
and both of them are of type II.  The peak magnitudes of them was
about 17.5--18, so the new-comer SN 1999eb is quite brighter!
Possibly SN 1999eb is as bright as SNeIa, which is expected to reach
16 mag or so at this distance (v_r = 5400km/s).  The followup
magnitude estimate is quite important.

  For the second, SN 1999ec was discovered on Oct. 2.5 and 3.5, and
confirmed on the earlier image also.  The location is: R.A. =
6h16m16s.16, Decl. = -21 22'09".8 (2000.0), which is about 82" west
and 12" north from the interacting Sbc galaxy NGC 2207.  It is
overposed on the knot in the outermost arm, and there are many
confusing stars around the SN.  Observers should do the identification
very carefully. 

  The reported magnitudes (unfilitered CCD) by discoverer are;

Sept. 20.5  17.5
Oct.   2.5  17.9
Oct.   3.5  17.9

, from which it seems that the peak magnitude has been passed.  

  This host galaxy is interacting with the eastern IC 2613, which is
on opposite side of SN 1999ec.  It is possibly that SN 1999ec is
gravitational-collapsed event of the massive star produced due to the
galaxy interaction.  

  The recession velocity of these pair is about 2700 km/s, from which
the expected maximum of unscatterred SNeIa is around 14.5 mag.  These
pair has produced another SN 1975A, which was observed as m_pv = 14.4.

  The discovery images of these new SNe are available on the
discoverer's site: http://astron.berkeley.edu/~bait/1999/sn99eb.html
and sn99ec.html, which are very useful for identifications.

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

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