Electronic Telegram No. 2328
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Room 209; Dept. of Earth and Planetary
 Sciences; Harvard University; 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbat@iau.org; cbatiau@eps.harvard.edu
URL http://www.cfa.harvard.edu/iau/cbat.html


SUPERNOVAE 2010dq AND 2010dr
     P. Challis, R. J. Foley, R. Kirshner, E. Berger, A. Soderberg and G. H.
Marion, Harvard-Smithsonian Center for Astrophysics, report that CCD spectra
(range 345-865 nm), obtained on June 17 UT with the 6.5-m MMT (+ Blue Channel
spectrograph) at Mount Hopkins, show that 2010dq (cf. CBET 2303) is type-Ia
supernova.  SN 2010dq shows the prominent Ti II feature associated with
low-luminosity supernovae like SN 1991bg near maximum light (e.g., Filippenko
et al. 1992, A.J. 104, 1543; Leibundgut et al. 1993 A.J. 105, 301).  The Si
II absorption is blueshifted by 11350 km/s.  Cross-correlation with a library
of supernova spectra, using the "SuperNova IDentification" code (SNID;
Blondin and Tonry 2007, Ap.J. 666, 1024), indicates that 2010dq is most
similar to SN 1991bg at three days after maximum brightness.
     Observations with the same equipment show that 2010dr (cf. CBET 2304) is
a type-II supernova.  The H-alpha and H-beta lines of 2010dr have only broad
triangular emission components.  H-alpha has a FWHM of 7500 km/s.  The
spectrum is similar to those of SN 1979C (e.g., Panagia et al. 1980, MNRAS
192, 861) and SN 1998S (e.g., Leonard et al. 2000, Ap.J. 536, 239) a few
months past maximum brightness; no narrow component is detected, suggesting
that SN 2010dr is likely of type IIL.

     K. Kinugasa, H. Takahashi, and O.Hashimoto, Gunma Astronomical
Observatory (GAO), write that a low-resolution spectrum (range 420-800 nm;
resolution about 500) of 2010dq was obtained on June 16.7 UT with the GAO
1.5-m telescope (+ GLOWS).  The spectrum most resembles to that of a typical
type-Ia supernova.  Comparison with a library of spectra via the "Supernova
Identification" code (Blondin and Tonry 2007, Ap.J. 666, 1024) indicates that
2010dq is most nearly similar to SN 1992A about 9 days after maximum.
Adopting the NED recession velocity of 5440 km/s for NGC 57 (de Vaucouleurs
et al. 1991, Third Reference Catalogue of Bright Galaxies, ver. 3.9), the
expansion velocity derived from the Si II absorption minimum (rest 635.5 nm)
is about 9500 km/s.


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

                         (C) Copyright 2010 CBAT