Detection of new Optical Counterpart candidates to PSR B1951+32 with   HST/WFPC2
  There remain several definitive gamma-ray pulsars that are as yet undetected in the optical regime. A classic case is the pulsar PSR B1951+32, associated with the complex CTB 80 SNR. Previous ground based high speed 2-d optical studies have ruled out candidates to V ~ 24. Hester (2000a) has reported an analysis of archival HST/WFPC2 observations of the CTB 80 complex which suggest a compact synchrotron nebula coincident with the pulsar's radio position. Performing a similar analysis, we have identified a possible optical counterpart within this synchrotron nebula at V ~ 25.5 - 26, and another optical counterpart candidate nearby at V ~ 24.5. We assess the reality of these counterpart candidates in the context of existing models of pulsar emission. 
R.F. Butler, A. Golden, A. Shearer (National University of Ireland,   Galway)