[vsnet-alert 3805] SN 1999gi in NGC 3184

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

Dear SN watchers,

  Very nearby supernova has been discovered.  The distance of the host
galaxy is about a half way to the Virgo center.  The followup
photometries are especially encouraged.

  According to IAUC 7329, a Japanese amateur R. Kushida has discovered
a new object (mag 14.5) superposed on NGC 3184 at Dec. 9.82 UT.  It is
her 9th discovery (including independent ones). Congratulations!  The
position measured by Y. Kushida is: R.A. = 10h18m16s.66, Decl. =
+41o26'28".2 (J2000.0), which is 3".5 west and 60".5 north of the
center of the face-on Scd galaxy NGC 3184.  This galaxy has two
apparently bright arms, and SN is superposed on the northern arm.  On
DSS2 image, the location is coincident to a blob.  The spectroscopy
has revealed that it is of type II in the early phase. 

  There are some foreground stars superposing the disk.  The
brightests are listed by Prof. Skiff (vsnet-chart 234 = vsnet-chat
2440) as:

Name      RA  (2000)  Dec    s     GSC       V    B-V   V-R   V-I 
A      10 18 16.4  +41 27 15 G  3004-0998  11.99  0.58  0.33  0.65 
B      10 18 19.9  +41 25 44 G  3004-0774  15.66  0.69
C      10 18 03.8  +41 23 49 A             15.81  0.66

The rough offsets from the nucleus of the host are: 3"W108"N,
33"E16"N, 62"W37"S for A, B, C, respectingly.  GSC magnitudes for A
and B are about 0.4 mag brighter than this photometry.  USNO-A1.0
(thus the VSNET sequence, vsnet-chart 232) does not contain the star
B and C, and the USNO magnitudes for star A are quite different 
(1434 on VSNET chart) from above list.  

  NGC 3184 has produced (at least) other 3 supernovae in this century;
SNe 1921B, 1921C and 1937F.  SN 1921C was of type Ia and peaked at
m_pv = 10.9, and other two are of type II, which were observed as m_pv
= 13.5 order.  Interestingly, all of these three are appeared far
south from the galaxy.  SN 1999gi is the first supernova observed in
the northern half of this galaxy, and the nearest one to its center.

  The distance of the host galaxy is about a half way to the Virgo
cluster.  From Turry-Fisher distance catalog (Bottinelli et al. 1984,
A&AS 56, 381), the distance module m-M is about 30.6.  The recession-
velocity-based one (Turry's catalog) says that it is 29.71.  The peak
magnitude of SN 1921C suggest that the latter would be better.  Thus,
the distance is not larger than 10 Mpc.

  The spectrum indicates that SN 1999gi is affected somewhat large
absorption by the dust cloud in the host galaxy.  Then the brightness
of this SN should be somewhat lower than the previous examples.
However, it is quite bright one as type II SNe.  The followup
photometry and observation by other methods are surely encouraged.

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

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp