PESSTO is the “Public ESO Spectroscopic Survey of Transient Objects” using the ESO New Technology Telescope and the EFOSC2 (optical) and SOFI (NIR) spectrographs. It is one of two currently running public spectroscopic surveys at ESO.

The construction of wide-field optical telescopes equipped with digital cameras with fields of view between 5-10 square degrees means that nearly the entire sky could be repeatedly surveyed in less than a month. These synoptic surveys are discovering new classes of transients that challenge our ideas of the physics of the explosions. We are beginning to see a diversity in the transient Universe that very likely depends on the progenitor stellar mass, metallicity, binarity and rotation.

This project was supported by the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC Grant ULTRAS to S. Smartt

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PESSTO in a nutshell

  • 90n per year on the NTT: 9 months, 10n per month (we are not observing May-July)
  • 4 yrs, with 1 more pending formal review
  • Optical and NIR spectra of transients with EFOSC2 + SOFI
  • We aim to classify around 2000 supernovae
  • Classification target range : r < 20 mag
  • We aim to provide 150 supernovae (or unusual optical transients) with full spectroscopic time series coverage (around 10 epochs of spectra)
  • Surveys partners are La Silla-Quest, SkyMapper, Pan-STARRS1, CHASE

PESSTO Data products

All raw data are immediately available in the ESO archive and instructions on downloading the reduced spectral and imaging data are available on our data page.

Optical spectra will be in one of three configurations:

  1. Classification (“C”) setting with Grism #13 : 3685-9315Å (17.7Å resolution)
  2. Blue (“B”) Setting with Grism #11: 3380-7520Å (13Å resolution)
  3. Red (“R”) Setting with Grism #16 : 6015-10320Å (13Å resolution)


SOFI spectra for selected targets will be taken with the following configurations:

  • Blue Grism : 0.93-1.67m
  • Red Grism : 1.50-2.50m

SOFI spectral targets will be within the range 14 < H < 17 (50 > S/N in continuum > 20)

SOFI imaging will also be obtained in JHK for selected targets.