[BAA 00223] SUPERNOVA 2006X IN NGC 4321 - M100

[Rick]

The Central Bureau for Astronomical Telegrams report in Circular No. 8667 and in Electronic Telegram No. 393 the discovery of a supernova in this well known galaxy at about magnitude 15.3 and brightening.  Tom Boles also advises that no x-ray transient has yet been seen.
                                             
SUPERNOVAE 2006X discovered independently by  Shoji Suzuki (Ooami-Shirasato, Chiba, Japan, via twelve CCD frames taken on Feb. 4 with a 0.32-m f/9 telescope + SBIG infrared-cut filter; communicated via M. Soma, National Astronomical Observatory of Japan) and by M. Migliardi (Cortina, Italy, via the CROSS program; cf. IAUC 7373; source of the tabulated data below for 2006X; communicated by A. Dimai).

Code Select Expand


SN      2006 UT      R.A.  (2000.0)  Decl.    Mag.     Offset
2006X   Feb. 7.10   12 22 53.99  +15 48 33.1  15.3  12" W, 48" S

    Dimai adds that 2006X does not appear on Palomar Sky Survey infrared, red, and blue plates.  Soma provides his rough measurement of the position end figures for 2006X from Suzuki's discovery frame:  53s, 48'.5.
                     
    R. Quimby, University of Texas; P. Brown, Pennsylvania State University; and C. Gerardy, Imperial College, report that a spectrogram (range 420-890 nm) of 2006X (cf. IAUC 8667), obtained on Feb. 8.35 UT with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by S. C. Odewahn and S. Rostopchin under poor conditions, shows it to be an early type-Ia supernova.  The spectra are similar to those of SN 2002bo at 1-2 weeks before maximum light (Benetti et al. 2004, MNRAS 348, 261), but with a redder continuum.  Adopting the recession velocity of 1571 km/s for the host (Rand 1995, A.J. 109, 2444, via NED), the velocity of the Si II 635.5-nm minimum is 20700 km/s.

    R. Quimby and M. Sellers, University of Texas, add that SN 2006X appeared at mag about 15.3 on unfiltered CCD images taken on Feb. 7.31 UT with the 0.45-m ROTSE-IIIb telescope at the McDonald Observatory; the position for 2006X was measured as R.A. =
12h22m53s.88, Decl. = +15o48'31".9 (equinox 2000.0; uncertainty +/- 0".6).  SN 2006X was not detected in ROTSE-IIIb images taken Feb. 1.32 (limiting mag about 17.9) or in a co-addition of images taken between 2004 Dec. 11 and 2005 June 8 (limiting mag about 19.0).

(C) Copyright 2006 CBAT
2006 February 8 (CBET 393) Daniel W. E. Green

I am grateful to Tom Boles and Callum Potter for communicating this information.
Roger Pickard, Director VSS

[Mike]

Sounds like an interesting project for the CCD imagers amongst us.

[Rick]

Also, look back through any recent images you've taken of that patch of sky to see whether you've got any pre-discovery images of it. Of course the weather recently hasn't exactly made that likely...