PESSTO : survey description and products from the first data release by the Public ESO Spectroscopic Survey of Transient Objects

TL;DR

PESSTO is a public spectroscopic survey of transient objects that provides extensive optical and NIR spectra and imaging, with data publicly available through ESO, aiming to enhance understanding of supernova extremes.

Contribution

This paper describes the data reduction strategies and publicly available data products from PESSTO's first data release, including spectra and imaging of transient objects.

Findings

First year data includes 814 EFOSC2 spectra and 95 SOFI spectra of 298 objects.

Spectra cover 3345-9995A (optical) and 0.935-2.53 micron (NIR) with specified resolutions.

Flux calibration accuracy is estimated at 15% absolute and 5% relative.

Abstract

The Public European Southern Observatory Spectroscopic Survey of Transient Objects (PESSTO) began as a public spectroscopic survey in April 2012. We describe the data reduction strategy and data products which are publicly available through the ESO archive as the Spectroscopic Survey Data Release 1 (SSDR1). PESSTO uses the New Technology Telescope with EFOSC2 and SOFI to provide optical and NIR spectroscopy and imaging. We target supernovae and optical transients brighter than 20.5mag for classification. Science targets are then selected for follow-up based on the PESSTO science goal of extending knowledge of the extremes of the supernova population. The EFOSC2 spectra cover 3345-9995A (at resolutions of 13-18 Angs) and SOFI spectra cover 0.935-2.53 micron (resolutions 23-33 Angs) along with JHK imaging. This data release contains spectra from the first year (April 2012 - 2013), consisting of all 814 EFOSC2 spectra and 95 SOFI spectra (covering 298 distinct objects), in standard ESO Phase 3 format. We estimate the accuracy of the absolute flux calibrations for EFOSC2 to be typically 15%, and the relative flux calibration accuracy to be about 5%. The PESSTO standard NIR reduction process does not yet produce high accuracy absolute spectrophotometry but the SOFI JHK imaging will improve this. Future data releases will focus on improving the automated flux calibration of the data products.