While PS1 is working well in producing regular transient stream for the Medium Deep Survey fields, these are typically too faint for NTT+EFOSC2. Mean mag is r~22, with typically ~100 targets per year in the MDS fields brighter than r~21 at peak. Only 4 of these fields are accessible from the south, so the MDS fields are not a viable source of targets for PESSTO.

The 3Pi search is starting to make progress and transients and vast numbers of asteroids have been discovered. The data is certainly good enough for a wide-field, local Universe search (similar mag limits to PTF, LaSILLA/QUEST and SkyMapper), and it is a matter of getting the processing up to speed.

  • Annual search Period : working throughout the year. The 3Pi survey goes to -30. Hence 2Pi of the sky (or 2/3 of PS1 survey) is within the +30 to -30 range.
  • Cadence : the 3Pi will revisit the same patch of sky 6 times in lunation, with a typical cadence of 5 days.
  • Depth : ~21.5
  • Status and start date : 3Pi is running regularly. Asteroids are easily found in the TTI pairs (pairs of ~30s exposures, separated by ~15mins on any one night). Hence if the difference imaging can be organised efficiently the search will very quickly get going. QUB have the software infrastructure in place to deal with the targets once PS1 is producing candidates.
  • Length of survey and long term status: Gauranteed only to Oct. 2012. Negotiations underway for extension of 1yr, plus plans for a PS1+PS2 survey longer term.

Targets and Selection

The 3Pi survey targets are here

In terms of finding real supernovae through the machine classification

  • If machine classification is AGN, then it's an AGN at >90% confidence
  • If machine classification is SN, AND the host object is an SDSS classified "galaxy" (by morphology), then ~80% confidence that it's a real SN (the rest are AGNs)
  • If machine classification is SN, and the host object is a "star", then again 90% confidence it is a Galactic transient
  • If machine classification is SN, and the host object is a "faint source" (which means r>21) we don't trust the star/galaxy separation of SDSS and we assume it could be a galaxy. About ~50-60% are SNe (but this number is exactly what we want to find out in FGSS!).