Scientific assessment of the quality of OSIRIS images

¹ Max-Planck Institut für Sonnensystemforschung, Justus-von-Liebig-Weg, 2 37077 Göttingen, Germany .
e-mail: tubiana@mps.mpg.de
² Centro di Ateneo di Studi ed Attivita Spaziali “Giuseppe Colombo” (CISAS), University of Padova via Venezia 15 35131 Padova Italy
³ Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
⁴ LESIA-Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Université Paris Diderot, 5, Place J. Janssen, 92195 Meudon Principal Cedex, France
⁵ Instituto de Astrofísica de Andalucía (CSIC), c/ Glorieta de la Astronomia s/n, 18008 Granada, Spain
⁶ Dipartimento di Fisica ed Astronomia, Università di Padova, via Marzolo 8, 35131 Padova, Italy
⁷ University of Padova, Department of Physics and Astronomy, Vicolo dell’ Osservatorio 3, 35122 Padova, Italy
⁸ Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
⁹ Centro de Astrobiologia, CSIC-INTA, 28850 Torrejon de Ardoz, Madrid, Spain
¹⁰ International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland
¹¹ Scientific Support Office, European Space Research and Technology Centre/ESA, Keplerlaan 1, Postbus 299, 2201 AZ Noordwijk ZH, The Netherlands
¹² Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
¹³ PAS Space Research Center, Bartycka 18A, 00716 Warszawa, Poland
¹⁴ Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstrsse 2, 12489 Berlin, Germany
¹⁵ Institut für Geophysik und extraterrestrische Physik (IGEP), Technische Universität Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
¹⁶ LATMOS, CNRS/UVSQ/IPSL, 11 boulevard d’Alembert, 78280 Guyancourt, France
¹⁷ INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
¹⁸ CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy
¹⁹ Department of Industrial Engineering, University of Padova, via Venezia 1, 35131 Padova, Italy
²⁰ University of Trento, via Sommarive 9, 38123 Trento, Italy
²¹ Physikalisches Institut der Universität Bern, Sidlerstr. 5, 3012 Bern, Switzerland
²² INAF–Osservatorio Astronomico di Trieste, via Tiepolo 11, 34014 Trieste, Italy
²³ Graduate Institute of Astronomy, National Central University, 300 Chung-Da Rd, 32054 Chung-Li, Taiwan
²⁴ Space Science Institute, Macau University of Science and Technology, Macao, PR China
²⁵ Operations Department, European SpaceAstronomy Centre/ESA, PO Box 78, 28691 Villanueva de la Cañada (Madrid), Spain
²⁶ Dipartimento di Geoscienze, University of Padova, via Gradenigo 6, 35131 Padova, Italy
²⁷ Institut für Datentechnik und Kommunikationsnetze der TU Braunschweig, Hans-Sommer-Str. 66, 38106 Braunschweig, Germany
²⁸ Department of Information Engineering, University of Padova, via Gradenigo 6/B, 35131 Padova, Italy
²⁹ Center for Space and Habitability, University of Bern, 3012 Bern, Switzerland

Received: 27 February 2015
Accepted: 11 August 2015

Abstract

Context. OSIRIS, the scientific imaging system onboard the ESA Rosetta spacecraft, has been imaging the nucleus of comet 67P/Churyumov-Gerasimenko and its dust and gas environment since March 2014. The images serve different scientific goals, from morphology and composition studies of the nucleus surface, to the motion and trajectories of dust grains, the general structure of the dust coma, the morphology and intensity of jets, gas distribution, mass loss, and dust and gas production rates.

Aims. We present the calibration of the raw images taken by OSIRIS and address the accuracy that we can expect in our scientific results based on the accuracy of the calibration steps that we have performed.

Methods. We describe the pipeline that has been developed to automatically calibrate the OSIRIS images. Through a series of steps, radiometrically calibrated and distortion corrected images are produced and can be used for scientific studies. Calibration campaigns were run on the ground before launch and throughout the years in flight to determine the parameters that are used to calibrate the images and to verify their evolution with time. We describe how these parameters were determined and we address their accuracy.

Results. We provide a guideline to the level of trust that can be put into the various studies performed with OSIRIS images, based on the accuracy of the image calibration.