Probable supernova discovered in NGC 4258 (Messier 106) by Pan-STARRS1.
ATel #6156; S. J. Smartt, K. W. Smith, D. Wright, D. R. Young, R. Kotak, M. Nicholl, J. Polshaw, C. Inserra, T.-W. Chen, G. Terreran, E. Gall, M. Fraser, M. McCrum (Queen's University Belfast), S. Valenti (LCOGT), R. Foley (Univ. of Illinois), A. Lawrence (Univ. Of Edinburgh), S. Gezari (Univ. of Maryland), W. Burgett, K. Chambers, M. Huber, R. P. Kudritzki, E. Magnier, J. Morgan, J. Tonry, W. Sweeney, C. Waters (IfA, Hawaii) C. Stubbs, R. Kirshner (Harvard), N. Metcalfe, P. Draper (Univ. of Durham) A. Rest (STScI)
on 21 May 2014; 16:26 UT
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Subjects: Optical, Supernovae
The Pan-STARRS1 telescope has discovered a suspected supernova near the core of NGC4258 (Messier 106) as part of the 3pi survey (see ATel #5850). The transient, currently designated PS1-14xz, was observed at coordinates 12:18:57.71 +47:18:11.3 (J2000) by PS1 on 2014 May 19.25 and had a a magnitude of z=14.77 (in the PS1 z-band system as defined by Tonry et al. 2012, ApJ 750, 99).
It is detected in 4 separate 30 sec z-band images, taken over a 7 minute interval. PS1 does not have a useful constraint on the epoch of explosion before this date, with the last image of this field taken 2014 March 24. All available PS1 information is available here : http://star.pst.qub.ac.uk/ps1threepi/psdb/candidate/1121857711471811300/
At a distance of 7.6 Mpc (Humphreys et al. 2013, ApJ, 775, 13), the absolute magnitude of M_z = -14.6 suggests it is either a young supernova, heavily reddened or intrinsically faint. Confirmation images are required and spectroscopic classification is required as soon as possible. NGC4258 has a maser distance (Humphreys et al. 2013) and a Cepheid distance (Macri et al. 2006 ApJ, 652, 1133) and is used as a calibrator in the extragalactic distance scale (Riess et al. 2011, ApJ, 730).
Information on the PS1 3Pi transient search is available in ATel #5850 and at http://star.pst.qub.ac.uk/ps1threepi/psdb/