This is a variable source discovered near the core
of MS1512. The source is brighter in images from 2004
July 18 and 19 than it was during 2002 April and June,
and the variability is confirmed with both CPM and ISIS. 
However, the source PSF is consistent with being stellar.
Also, comparing the reference images from April and June,
no significant variability is detected, though a trace may be
visible with CPM. All in all, a somewhat suspect SN candidate.

Analysis of HST images by Keren shows variability in the V555
band (1996 - 1997) and marginal variability in the I814 band 
(1997 - 2001) - therefore, this must be an AGN.

HST mags:

F555W:
  96
  counts:9922.6      flux:3.28E-29      ABmag: 22.6   
  centerwv: 5439.   exptime: 10400.   photflam:3.482925E-18

  97
  counts:4185.2      flux:2.28E-29     ABmag: 23.0
  centerwv: 5439.   exptime: 6300.   photflam:3.482925E-18 


F675w:
  96
  counts:3132.4     flux:3.10E-29      ABmag: 22.7   
  centerwv: 6717.   exptime: 4400.   photflam:2.898974E-18 


F814W:
  97
  counts:18971.5   flux:5.14E-29       ABmag: 22.12   
  centerwv: 8012.  exptime: 19800.   photflam:2.507987E-18   
  (notice the depth of this image... i also attached it, to replace the one i
  sent you before)

  2001
  counts:3617.       flux:4.85E-29      ABmag: 22.18   
  centerwv: 8012.   exptime: 4000.   photflam:2.507987E-18