{{Unreferenced, date=December 2009 In

observational astronomy Observational astronomy is a division of astronomy that is concerned with recording data about the observable universe, in contrast with theoretical astronomy, which is mainly concerned with calculating the measurable implications of physical ...

an On-The-Fly Calibration (OTFC) system calibrates data when a user's request for the data is processed so that users can obtain data that are calibrated with up-to-date calibration files, parameters, and software.

History of OTFC

The OTFC processing system was developed at the Canadian Astronomy Data Centre (CADC) and the

Space Telescope European Coordinating Facility right The Space Telescope – European Coordinating Facility (ST-ECF) was an institution which provided a number of support and service functions primarily for European observers of the NASA/ESA Hubble Space Telescope (HST). It was established in 1 ...

(ST-ECF) and is implemented at both sites and at

Space Telescope Science Institute The Space Telescope Science Institute (STScI) is the science operations center for the Hubble Space Telescope (HST), science operations and mission operations center for the James Webb Space Telescope (JWST), and science operations center for the ...

(STScI). The OTFC system currently provides data calibration for the Wide Field and Planetary Camera 2 (WFPC2) and

Space Telescope Imaging Spectrograph The Space Telescope Imaging Spectrograph (STIS) is a spectrograph, also with a camera mode, installed on the Hubble Space Telescope. Aerospace engineer Bruce Woodgate of the Goddard Space Flight Center was the principal investigator and creato ...

(STIS). In the future, the Advanced Camera for Surveys (ACS) and possibly the

Near Infrared Camera and Multi-Object Spectrometer The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is a scientific instrument for infrared astronomy, installed on the Hubble Space Telescope (HST), operating from 1997 to 1999, and from 2002 to 2008. Images produced by NICMOS contain ...

(NICMOS) will be supported.

Goals of the system

The main goals behind the implementation of the OTFC system are to take advantage of better calibration files and the much smaller storage area required if only raw files are kept in the archives. The system can also offer more calibration steps than were available when the data was first released and can implement improved pipeline software. Currently, for example, HST data are calibrated as they are received at the STScI. Raw and calibrated data are stored in the HST archive (DADS). Frequently, users must recalibrate the data at their home sites to take advantage of better calibration files or software. A large fraction (over 90%) of the calibrated data in the HST archive could be improved by recalibration, although the improvements are not always significant. In the past, instruments that undergo evolution of calibration files or calibration software often required users to carry out their own recalibrations at their home sites. With OTFC, the HST data archives carry out the recalibration. Hubble Space Telescope Space imagers