SN 2011dn in ugc11501 - June 21, 2011

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SN 2011dn (A.R. 19 58 35.52, Dec. +02 36 16.2) discovered on June 21 in the galaxy UGC 11501 (offset 126W 0N), magnitude 17.5, type Ia.

SN discovered by Simone Leonini with the 53 cm Ritchey Chretien telescope of the Montarrenti Observatory (Siena).

UGC 11501 is a SAB galaxy in the 'Aquila constellation, at 106 Mpc, magnitude 13.8.

                                                  Electronic Telegram No. 2746
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director: Daniel W. E. Green; Hoffman Lab 209; Harvard University;
20 Oxford St.; Cambridge, MA 02138; U.S.A.
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Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2011dn IN UGC 11501 = PSN J19583553+0236163
Simone Leonini, Siena, Italy, reports the discovery of an apparent
supernova (mag about 16.8) on an unfiltered CCD image (limiting mag about
19.2) taken on June 21.931 UT during the Montarrenti Observatory Supernovae
Search program (part of the Italian Supernovae Project) using a 0.53-m f/7.8
Ritchey-Chretien telescope (+ Apogee Alta U47 CCD camera). The new object is
located at R.A. = 19h58m35s.53, Decl. = +2d36'16".3 (equinox 2000.0), which is
26" west of the nucleus of the galaxy UGC 11501. No stellar source is visible
at this position in their past images from 2009 June 16 to 2011 May 30
(limiting mag about 19.0) or on Palomar Sky Survey infrared, red, and blue
plates (1995 August 16, F plate; 1992 July 1, J plate; 1990 June 20, N plate,
limiting mag 20.0). Confirmation images were obtained on 2011 June 22.93 by
L. M. Tinjaca Ramirez using the discovery telescope, with the variable then at
(mag about 17.1; limiting mag about 19.2). The new object was designated
PSN J19583553+0236163 when posted at the Central Bureau's TOCP webpage and is
here designated SN 2011dn based on the spectroscopic report below. The
discovery image is posted at the following website URL:
http://www.jacopobaldi.it/dati/PSN%20in%20UGC11501.jpg, and the confirmation
at http://www.jacopobaldi.it/dati/confirmation%20PSN%20in%20UGC11501.jpg.
Additional unfiltered CCD magnitudes for SN 2011dn: June 23.23-23.30
UT, 16.5 (R. A. Koff, Bennett, CO, U.S.A.; Celestron 0.20-m f/10 reflector +
SBIG ST-6 CCD camera; multiple co-added images); 23.354, 16.1 (Joseph
Brimacombe, Cairns, Australia; three co-added 60-s images; position end
figures 35s.56, 11".3). Brimacombe's image is posted at the following
website URL: http://www.flickr.com/photos/43846774@N02/5865118910/.

D. C. Leonard, San Diego State University; J. Moustakas, University of
California at San Diego; B. J. Swift and D. McCarthy, University of Arizona;
V. Bailey, E. Carrico, A. Carter, E. Chui, E. Douglas, E. Eggeman, R. Goldberg,
R. Grant, K. Hartman, J. Hellerstein, E. Hooper, C. Horlick-Cruz, L. Hunter, T.
Jiles, E. D. Johnson, K. Kumar, L. Lappe, J. Lee, W. Lee, F. Marsh, G. Mehta,
P. Miller, R. Rampalli, J. Reed, K. Rice, H. Saldivar, M. Salgado-Flores, A.
Schlingman, W. F. Schlingman, W. M. Schlingman, S. Scibelli, K. Sinclair, I.
Steincamp, N. Stock, N. Todd, L. L. Aizpuru Vargas, S. Yamanaka, and E.
Zachary, 2011 Advanced Teen Astronomy Camp, report that inspection of a
low-dispersion optical spectrum (range 370-690 nm) of PSN J19583553+0236163 =
SN 2011dn, obtained with the 2.3-m Bok telescope (+ Boller & Chivens
spectrograph) at Steward Observatory on June 23 UT, shows it to be a type-Ia
supernova of the SN-1991T-like sub-class, several days before maximum light.
Cross-correlation with a library of supernova spectra using the "Supernova
Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) finds
good matches with pre-maximum (-6.4 +/- 2.7 days) template spectra of SN
1991T, SN 1997br, and SN 1999aa. Adopting the NASA/IPAC Extragalactic
Database (NED) recession velocity for UGC 11501 of 7572 km/s (a 21-cm H I
line measurement taken from Springob et al. 2005, Ap.J. Suppl. 160, 149),
the maximum absorption in the (weak) Si II line (rest 635.5 nm) is
blueshifted by approximately 10100 km/s.


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

(C) Copyright 2011 CBAT
2011 June 24 (CBET 2746) Daniel W. E. Green