Editing Hubble Space Telescope (section)

== Hubble data ==
[[File:Hubble stretches the stellar tape measure ten times further.jpg|thumb|upright=1.4|Hubble precision stellar distance measurement has been extended ten times further into the [[Milky Way]].<ref>{{cite news |title=Hubble stretches the stellar tape measure ten times further |url=http://www.spacetelescope.org/images/opo1423a/ |access-date=April 12, 2014 |newspaper=ESA/Hubble Images |archive-date=October 30, 2017 |archive-url=https://web.archive.org/web/20171030104602/http://www.spacetelescope.org/images/opo1423a/ |url-status=live }}</ref>]]

=== Transmission to Earth ===
Hubble data was initially stored on the spacecraft. When launched, the storage facilities were old-fashioned reel-to-reel [[tape drive]]s, but these were replaced by [[solid-state drive|solid state]] data storage facilities during servicing missions{{nbsp}}2 and 3A. About twice daily, the Hubble Space Telescope radios data to a satellite in the [[geosynchronous]] [[Tracking and Data Relay Satellite System]] (TDRSS), which then downlinks the science data to one of two 60-foot (18-meter) diameter high-gain microwave antennas located at the [[White Sands Test Facility]] in [[White Sands, New Mexico]].<ref name="Telemetry">{{cite web |title=Team Hubble |url=http://hubblesite.org/the_telescope/team_hubble/ |url-status=dead |archive-url=https://web.archive.org/web/20121028183242/http://hubblesite.org/the_telescope/team_hubble/ |archive-date=October 28, 2012 |access-date=November 5, 2012 |website=HubbleSite.org |publisher=[[Space Telescope Science Institute]]}}</ref> From there they are sent to the Space Telescope Operations Control Center at Goddard Space Flight Center, and finally to the Space Telescope Science Institute for archiving.<ref name="Telemetry" /> Each week, HST downlinks approximately 140 gigabits of data.<ref name="hubblesite-facts" />

=== Color images ===
[[File:Cumulative-absorption-spectrum-hubble-telescope.jpg|thumb|upright=1.8|right|Data analysis of a spectrum revealing the chemistry of hidden clouds]]

All images from Hubble are [[monochrome|monochromatic]] [[grayscale]], taken through a variety of filters, each passing specific wavelengths of light, and incorporated in each camera. Color images are created by combining separate monochrome images taken through different filters. This process can also create [[false-color]] versions of images including infrared and ultraviolet channels, where infrared is typically rendered as a deep red and ultraviolet is rendered as a deep blue.<ref name="space20130724">{{cite web |url=http://www.space.com/22086-how-hubble-space-telescope-photos-work.html |title=The Secret Science of the Hubble Space Telescope's Amazing Images |work=Space.com |last=Rosen |first=Raphael |date=July 24, 2013 |access-date=July 26, 2013 |archive-date=May 12, 2019 |archive-url=https://web.archive.org/web/20190512063429/https://www.space.com/22086-how-hubble-space-telescope-photos-work.html |url-status=live }}</ref><ref>{{cite web |url=https://www.pbs.org/wgbh/nova/space/hubble-telescope.html |title=How Hubble Sees |work=Nova ScienceNow |publisher=PBS |first=Jeff |last=Hester |date=July 1, 2008 |access-date=August 17, 2015 |archive-date=October 15, 2018 |archive-url=https://web.archive.org/web/20181015045410/http://www.pbs.org/wgbh/nova/space/hubble-telescope.html |url-status=live }}</ref>

=== Archives ===
All Hubble data is eventually made available via the [[Space Telescope Science Institute|Mikulski Archive for Space Telescopes]] at [[Space Telescope Science Institute|STScI]],<ref>{{cite web |url=http://archive.stsci.edu/hst |title=The Hubble Telescope |publisher=STScI |access-date=April 26, 2008 |archive-date=May 30, 2012 |archive-url=https://archive.today/20120530063454/http://archive.stsci.edu/hst |url-status=live }}</ref> [[Canadian Astronomy Data Centre|CADC]]<ref>{{cite web|url=https://www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/en/hst/|title=CADC's Hubble Space Telescope Archive|publisher=CADC|access-date=April 11, 2022|archive-date=April 19, 2022|archive-url=https://web.archive.org/web/20220419234043/https://www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/en/hst/|url-status=live}}</ref> and [[European Space Astronomy Centre|ESA/ESAC]].<ref>{{cite web |url=http://www.sciops.esa.int/index.php?project=HST |title=European HST Archive at ESA/ESAC |publisher=ESA/ESAC |access-date=February 14, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130525154922/http://www.sciops.esa.int/index.php?project=HST |archive-date=May 25, 2013}}</ref> Data is usually proprietary—available only to the [[principal investigator]] (PI) and astronomers designated by the PI—for twelve months after being taken. The PI can apply to the director of the STScI to extend or reduce the proprietary period in some circumstances.{{sfn|Strolger|Rose|2017|p=53}}

Observations made on Director's Discretionary Time are exempt from the proprietary period, and are released to the public immediately. Calibration data such as flat fields and [[dark frame]]s are also publicly available straight away. All data in the archive is in the [[FITS]] format, which is suitable for astronomical analysis but not for public use.{{sfn|Rose|2017|p=69}} The [[Hubble Heritage Project]] processes and releases to the public a small selection of the most striking images in [[JPEG]] and [[Tagged Image File Format|TIFF]] formats.<ref name="heritage.stsci">{{cite web |url=http://heritage.stsci.edu/commonpages/infoindex/ourproject/moreproject.html |title=The Hubble Heritage Project |publisher=STScI |access-date=November 5, 2012 |archive-date=September 22, 2018 |archive-url=https://web.archive.org/web/20180922113323/http://heritage.stsci.edu/commonpages/infoindex/ourproject/moreproject.html |url-status=live }}</ref>

=== Pipeline reduction ===
Astronomical data taken with CCDs must undergo several calibration steps before they are suitable for astronomical analysis. STScI has developed sophisticated software that automatically calibrates data when they are requested from the archive using the best calibration files available. This 'on-the-fly' processing means large data requests can take a day or more to be processed and returned. The process by which data is calibrated automatically is known as 'pipeline reduction', and is increasingly common at major observatories. Astronomers may if they wish retrieve the calibration files themselves and run the pipeline reduction software locally. This may be desirable when calibration files other than those selected automatically need to be used.{{sfn|Rose|2017|pp=67–69}}

=== Data analysis ===
Hubble data can be analyzed using many different packages. STScI maintains the custom-made [[Space Telescope Science Data Analysis System]] (STSDAS) software, which contains all the programs needed to run pipeline reduction on raw data files, as well as many other astronomical image processing tools, tailored to the requirements of Hubble data. The software runs as a module of [[IRAF]], a popular astronomical data reduction program.{{sfn|Rose|2017|pp=68–69}}