Pre-explosion HST images of SN2009hd

ATel #2114; Dan Maoz (Tel-Aviv University)
on 8 Jul 2009; 12:14 UT
Credential Certification: Filippo Mannucci (filippo@arcetri.astro.it)

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I have analyzed pre-explosion Hubble Space Telescope images of the site of SN2009hd (CBET#1867) in M66 (NGC 3627). The summed images consist of WFPC2 images obtained between November 1997 and January 1998, with 24 orbits (58.8 ks) in F555W (V-band) and 10 orbits (25 ks) in F814W (I-band). The region is also covered in a 1.0 ks ACS F435W (B-band) exposure from December 2004. I have compared the HST images to an unfiltered image of the supernova, kindly obtained on July 5, UT 18 by E. Gorbikov and A. Shporer with the Wise Observatory 1m telescope using the LAIWO guider CCD in 1.7" seeing, and have localized the explosion site to about 0.5" in the HST images. The SN appears to have exploded in a particularly dusty region of the galaxy, consistent with reports (ATEL#2109, ATEL#2113) that the event is red and faint. The few detected stars on the edge of the pre-explosion error circle have AB magnitudes of about B=26, V=24 and I=23 (M_B=-4, M_V=-6, M_I=-7 assuming a distance of 10 Mpc and no extinction), corresponding to evolved stars of at least 12 M_sun (see Fig. 3 in Maoz & Mannucci 2008, MNRAS, 388, 421). Marked 15"x10" versions of the V- and I-band HST images can be found at http://wise-obs.tau.ac.il/~dani/sn2009hd/hstI.jpg http://wise-obs.tau.ac.il/~dani/sn2009hd/hstV.jpg