Supernova Gallery

Supernova 2005cs in M51

This pre-discovery image of Supernova 2005cs was taken the day before discovery but only identified after announcement on IAUC 8553 (subscription required).

This had been taken as the first light image following the replacement of a 12" telescope with a 16" on 23 June 2005, see the first light page for more details.

The position was measured from this image to be 

2005 June 27.933 UT:
R.A. = 13h 29m 52s.81 +/- 0s.03, Decl. = +47° 10' 35".3 +/-0".3 (equinox 2000.0)
Mag R = +16.6 +/-0.1

these details appearing on 2005 July 1st in IAUC 8555.

This image is sharper than the first light image taken on 2005 June 27 and with the supernova also being brighter allowed a more accurate position to be measured. Astrometry using 48 USNO B1.0 stars and photometry with 35 stars was derived using Astrometrica:

2005 July 06.940 UT:
R.A. = 13h 29m 52s.770 +/- 0s.019,   Decl. = +47° 10' 36".00 +/- 0".16 (equinox 2000.0)
Mag R = +14.25 +/- 0.01

and compares well with the proposed progenitor red giant star (IAUC 8556) identified on Hubble Space Telescope images with position end figures of 52s.760 and 36".11 and with a pre-outburst brightness of mag +24.0 +/- 0.2.