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Association (astronomy)
Encyclopedia
An association is a combined or co-added group of astronomical exposures from which cosmic rays have been removed. WFPC2 associations constitute one type of association and are tools in the Hubble Space Telescope
(HST) archive for using data from the Wide Field and Planetary Camera 2
(WFPC2). Associations were introduced in the HST archive at the beginning of 1998. Since then, astronomers have been able to retrieve on-the-fly re-calibrated co-added WFPC2 images that have already been cleaned of cosmic rays from the Space Telescope European Coordinating Facility
(ST-ECF), the Canadian Astronomy Data Centre (CADC) and Space Telescope Science Institute
(STScI) archives.
The development of a new association pipeline was started in early 1999. Standard cross-correlation techniques were used to measure the offsets among WFPC2 observations belonging to the same proposal and using the same filter. CADC and ST-ECF released the second generation of WFPC2 Associations, known as type B associations in November 2001.
Type B associations contain all the exposures that follow the same criterion of association as type A, but do not depend on the availability or the accuracy of the jitter information.
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
(HST) archive for using data from the Wide Field and Planetary Camera 2
Wide Field and Planetary Camera 2
The Wide Field and Planetary Camera 2 is a baby grand piano sized camera built by the Jet Propulsion Laboratory and formerly installed on the Hubble Space Telescope. It was installed by servicing mission 1 in 1993, replacing the telescope's original Wide Field and Planetary Camera...
(WFPC2). Associations were introduced in the HST archive at the beginning of 1998. Since then, astronomers have been able to retrieve on-the-fly re-calibrated co-added WFPC2 images that have already been cleaned of cosmic rays from the Space Telescope European Coordinating Facility
Space Telescope European Coordinating Facility
right|The Space Telescope - European Coordinating Facility is an institution which provides a number of support and service functions primarily for European observers of the NASA/ESA Hubble Space Telescope...
(ST-ECF), the Canadian Astronomy Data Centre (CADC) and Space Telescope Science Institute
Space Telescope Science Institute
The Space Telescope Science Institute is the science operations center for the Hubble Space Telescope and for the James Webb Space Telescope...
(STScI) archives.
History
Type B associations contain all the exposures that follow the same criterion of association as type A, but do not depend on the availability or the accuracy of the jitter information.