Cosmic shear from STIS pure parallels

I. Data

¹ ST-ECF, Karl-Schwarzschild Str. 2, Garching bei München 85748, Germany
² Max-Planck-Institut für Astrophysik, Karl-Schwarzschild Str. 1, 85741 Garching, Germany
³ Institut d'Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
⁴ Observatoire de Paris, DEMIRM 61, avenue de l'Observatoire, 75014 Paris, France
⁵ Institut für Astrophysik und Extraterrestrische Forschung der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
⁶ Department of Physics and Astronomy, University of Pennsylvania 209 S. 33rd Street, Philadelphia, PA 19104, USA
⁷ Universitäts-Sternwarte München, Scheiner Str. 1, 81679 München, Germany

Corresponding author: N. Pirzkal npirzkal@eso.org

Received: 20 February 2001
Accepted: 12 June 2001

Abstract

Following the second HST servicing mission in 1997 when the STIS instrument was installed and the capability for parallel observations was enhanced, a substantial archive of non-proprietary parallel data has been accumulating. In this paper, we discuss the use of unfiltered STIS imaging data for a project that requires deep observations along as many independent lines-of-sight as possible. We have developed a technique to determine which datasets in the archive can safely be co-added together and have developed an iterative co-addition technique which enabled us to produce 498 high-quality, deep images. The principal motivation for this work is to measure the Cosmic Shear on small angular scales and a value derived from these data will be presented in a subsequent paper. A valuable by-product of this work is a set of high quality combined fields which can be used for other projects. The data are publicly available at http://www.stecf.org/projects/shear/