[IAUC] CBET 1894: 20090803 : SUPERNOVAE 2009ht-2009hx

Lun Ago 3 18:19:35 ART 2009

                                                  Electronic Telegram No. 1894
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS en CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT en CFA.HARVARD.EDU (science)
URL http://www.cfa.harvard.edu/iau/cbat.html


SUPERNOVAE 2009ht-2009hx
     F. Yuan, University of Michigan; R. Quimby, California Institute of
Technology; J. Vinko, University of Texas; D. Chamarro, M. D. Sisson, C.
Akerlof, S. B. Pandey, University of Michigan; and J. C. Wheeler and E.
Chatzopoulos, University of Texas, on behalf of the ROTSE collaboration,
report the discovery of a type-Ia supernova (mag about 17.5) in unfiltered
CCD images taken on July 19.02 UT with the 0.45-m ROTSE-IIId telescope at
the TUBITAK National Observatory at Bakirlitepe, Turkey.  The new object,
designated 2009ht, was also detected on the same day with the ROTSE-IIIc
telescope at the H.E.S.S. site in Namibia.  SN 2009ht is located at R.A. =
0h56m46s.89, Decl. = -1o35'51".3 (equinox 2000.0), which is 5".1 east and 4".0
south of the center of a galaxy having z = 0.0459 in the SIMBAD database.
The supernova was discovered by subtracting a reference image built from
images taken in August 2008, and this field was not observed between Jan.
2009 and the discovery date.  A finding chart of the transient is posted at
URL http://www.rotse.net/rsvp/j005646.9-013551/j005646.9-013551.jpg.
A spectrum (range 320-1000 nm) obtained on July 22.58 UT with the
10-m Keck I (+ Low Resolution Imaging Spectrometer) shows 2009ht to be a
normal type-Ia supernova near maximum light.  Adopting the redshift of
the apparent host, the expansion velocity derived from the minimum of
the Si II (rest 635.5 nm) line is about 11000 km/s.

     Further to CBET 1866, D. Sand, Harvard-Smithsonian Center for Astrophysics
and the Las Cumbres Observatory Global Telescope Network; M. L. Graham and C.
Bildfell, University of Victoria; D. W. Just, S. Sivanandam, and S.
Herbert-Fort, Steward Observatory, C. J. Pritchet, University of Victoria; H.
Hoekstra, Leiden University; and D. Zaritsky, Steward Observatory, report
that five supernovae were discovered with g' and r'-band images obtained at
the Canada-France-Hawaii Telescope with Megacam, including an independent
discovery of 2009ht.  Spectroscopy was obtained with either the Hectospec
instrument (July 16, 2009hu and 2009hv) or the Blue Channel Spectrograph
(July 23, remaining three objects) on the MMT, as noted below.  The publicly
available Supernova Identification code of Blondin and Tonry (2007, Ap.J.
666, 1024) was utilized for determining spectroscopic types, indicating that
2009ht is a normal type-Ia supernova roughly a week past maximum, 2009hu is
a type-Ib supernova roughly at maximum light, 2009hv is a normal type-Ia
supernova around two weeks past maximum, 2009hw is a normal type-Ia
supernova around two days after maximum, and 2009hx is a normal type-Ia
supernova roughly one month after maximum.  The objects' discovery
magnitudes and spectroscopic redshift (z) are tabulated below:

 SN       2009 UT     R.A. (2000.0) Decl.       g'     r'      z
 2009ht   July 19    0 56 46.92  - 1 35 51.3   17.5   17.5    0.044
 2009hu   June 25   14 53 29.82  +18 35 31.1   22.6   21.9    0.13
 2009hv   June 25   14 54 32.92  +18 39 42.0   18.6   18.6    0.054
 2009hw   July 17   19 20 34.05  +43 33 45.6   19.1   18.6    0.06
 2009hx   July 17   22 49 12.74  +11 20 14.4   22.6   21.4    0.14

SN 2009ht is located 5".25 east and 3".83 south of its host galaxy (which
itself has magnitudes g' = 16.0 and r' = 15.2).  SN 2009hu had magnitudes
g' = 22.0 and r' = 21.2 on July 17; it is located 0".97 west and 2".87
south of its host galaxy (which itself has magnitudes g' = 19.2, r' =
18.6).  SN 2009hv had magnitudes g' = 19.6, r' = 18.9 on July 17; it is
located 0".26 east and 2".49 north of its host galaxy (which itself has
magnitudes g' = 23.8, r' = 23.4).  SN 2009hw is located 0".88 east and
1".93 south of the center of its host galaxy (which itself has magnitudes
g' = 17.4, r' = 16.8).  SN 2009hx has not apparent host galaxy to
limiting magnitudes around g = r = 24; further imaging after the supernova
has faded will further constrain the brightness of any possible host.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2009 CBAT
2009 August 3                    (CBET 1894)              Daniel W. E. Green