Central Bureau for Astronomical Telegrams
IAUC 8508: 2005bg; 2005bd, 2005be
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Circular No. 8508
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
SUPERNOVA 2005bg IN MCG +03-31-93
R. Quimby, P. Mondol, F. Castro, M. Sellers, P. Hoeflich, and
J. C. Wheeler, University of Texas; and C. Gerardy, Imperial
College, report the discovery of a supernova in unfiltered CCD
images taken with the 0.45-m ROTSE-IIIb telescope at McDonald
Observatory on Mar. 28.17 (with the new object at mag about 16.2)
and Apr. 2.16 UT (mag about 16.1). SN 2005bg is located at R.A. =
12h17m17s.18, Decl. = +16o22'17".6 (equinox 2000.0), which is 0".6
north and 0".4 east of the core of MCG +03-31-93. The new object
was found by subtracting a co-addition of images taken between 2004
Dec. 11 and 2005 Jan. 17 (limiting mag about 18.6); a similar
subtraction showed nothing at this location on Mar. 20.19 (limiting
mag about 17.2). A spectrum (range 430-890 nm) of the new object,
obtained on Apr. 7.13 with the 9.2-m Hobby/Eberly Telescope (+
Marcario Low-Resolution Spectrograph) by B. Roman and S. Rostopchin,
shows it to be a type-Ia supernova. Assuming the NED host-galaxy
recession velocity of 6921 km/s, the expansion velocity derived
from the minimum of the Si II 635.5-nm feature is 11000 km/s. The
spectrum also shows Mg II 448.1-nm, Fe II 508.3-nm, and S II 545.4-
and 564.0-nm lines; however, the Ca II infrared triplet is not
detected. Additional unfiltered CCD magnitudes for SN 2005bg:
Apr. 3.16 UT, 15.8; 5.15, 15.6.
SUPERNOVA 2005bd AND 2005be
M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian
Center for Astrophysics, report that a spectrum (range 340-730 nm)
of SN 2005bd (cf. IAUC 8505), obtained on Apr. 9.15 UT by H. Landt
with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows
it to be a type-Ia supernova with a spectral-feature age (cf. Riess
et al. 1997, A.J. 114, 722) of about 8 (+/- 2) days after maximum
light. The supernova expansion velocity, derived from the minimum
of Si II (rest 635.5 nm) and adopting the NED recession velocity of
11119 km/s for the host galaxy, is about 11000 km/s.
M. Salvo, B. Schmidt, and J. Norris, Australian National
University (ANU), report that a spectrum (range 360-530 nm) of SN
2005be (IAUC 8506) was taken at the ANU 2.3-m telescope (+ Double-
Beam spectrograph) at Siding Spring on Apr. 6.70 UT. Cross-
correlation with a library of supernovae spectra (see IAUC 8098)
shows SN 2005be to be a type-Ia supernova nearly a week past
maximum light, at a redshift z = 0.035. This is the same redshift
value found for the host galaxy from the position of the Ca H and K
lines in its spectrum.
(C) Copyright 2005 CBAT
2005 April 10 (8508) Daniel W. E. Green
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