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{{DISPLAYTITLE:The Planck mission}}
+
{{DISPLAYTITLE:Introduction}}
  
== Introduction ==
 
  
Planck is a satellite of the European Space Agency designed to answer key cosmological questions.
+
== The Planck mission ==
Its main goal is to determine the geometry and content of the Universe, and to distinguish between specific theories describing the birth and evolution of the Universe. To achieve this ambitious objective, it observed the [http://pdg.lbl.gov/2013/reviews/rpp2013-rev-cosmic-microwave-background.pdf  cosmic microwave background radiation]  (CMB), emitted about 14 billion years ago, around 380,000 years after the Big Bang. The CMB permeates the Universe and is observed to have a blackbody spectrum with a temperature of about 2.7 K. Small deviations from isotropy encode a wealth of information on the properties of the Universe in its infancy. The objective of Planck is to measure these properties with an unprecedented accuracy and level of detail.
 
  
[[file:Planck_Logos.jpg|thumb|300px|The Planck collaboration institutes and agencies.]]
+
[http://www.esa.int/Planck Planck] is a mission of the European
 
+
Space Agency - ESA. The Planck satellite carried instruments provided by two scientific Consortia funded by ESA member
As with all ESA scientific missions, Planck was developed in a partnership with the
+
states (in particular the lead countries: France and Italy) with contributions from [https://www.nasa.gov/ NASA] (USA), and
European scientific community. [[Planck Collaboration|Two consortia of scientific institutes]] (supported by several funding agencies),
 
each led by a Principal Investigator, developed and delivered to ESA an instrument designed specifically for
 
Planck. Each of these instruments targets a specific number of wavelength bands within the
 
range where the CMB is observable. Together, the two instruments are capable of collecting
 
data of sufficient quality to measure the CMB signal and distinguish it from other confusing
 
sources. A large telescope collected the light from the sky and delivered it to the instruments
 
for measurement and analysis. The reflectors of the Planck telescope were developed and
 
delivered to ESA by a Danish consortium of institutes.  NASA also contributed significantly to Planck.
 
ESA retains overall management of the project, including the responsibility to develop and procure the spacecraft, integrate
 
the instruments into the spacecraft, and launch and operate it. Planck was launched on May 14th 2009 on an Ariane 5 rocket,
 
together with the Herschel Space Observatory. After launch, they were both
 
placed into orbits around the second Lagrange point of the Sun-Earth system, located about 1.5 million km from the Earth. From that far
 
vantage point, Planck swept the sky regularly in large swaths, and covered it fully
 
about five times for the HFI and eight times for the LFI.
 
Each of the two instrument consortia operated their respective instrument and processed
 
all the data into usable scientific products. At specific intervals the consortia delivered the data products to ESA, which archives them
 
and distributes them to the community.
 
 
 
The last command to the Planck satellite was sent on the 23 October 2013, marking the end of operations.
 
[[file:PlanckMissionTimelineV2.png|thumb|480px|Timeline of the Planck operations and archiving.]]
 
 
 
== New Introduction ==
 
 
 
[http://www.esa.int/Planck Planck] is a project of the European
 
Space Agency - ESA - with instruments provided by two scientific Consortia funded by ESA member
 
states (in particular the lead countries: France and Italy) with contributions from NASA (USA), and
 
 
telescope reflectors provided in a collaboration between ESA and a scientific Consortium led and
 
telescope reflectors provided in a collaboration between ESA and a scientific Consortium led and
 
funded by Denmark.
 
funded by Denmark.
  
 
Planck was conceived in 1992, in the wake of the release of the results from the
 
Planck was conceived in 1992, in the wake of the release of the results from the
Cosmic Background Explorer (COBE) satellite, notably the measurement by the
+
Cosmic Background Explorer ([https://science.nasa.gov/missions/cobe COBE]) satellite, notably its measurement of the shape of the spectrum of the  
FIRAS instrument of the shape of the spectrum of the Cosmic Microwave Background (CMB), and the
+
[http://pdg.lbl.gov/2017/reviews/rpp2016-rev-cosmic-microwave-background.pdf cosmic microwave background]
detection by the DMR instrument of the spatial anisotropies of the temperature of the CMB. The
+
(CMB), and its
 +
detection of the spatial anisotropies of the temperature of the CMB. The
 
latter result in particular led to an explosion in the number of ground-based and suborbital
 
latter result in particular led to an explosion in the number of ground-based and suborbital
 
experiments dedicated to mapping of the anisotropies, and to proposals for space experiments both in
 
experiments dedicated to mapping of the anisotropies, and to proposals for space experiments both in
 
Europe and the USA.
 
Europe and the USA.
 +
 +
The main objective of Planck was to measure the spatial anisotropies of the temperature of the CMB, with an accuracy set by fundamental astrophysical limits. Its level of performance enabled Planck to extract essentially all the information in the CMB temperature anisotropies. Planck also measured to high accuracy the polarization of the CMB anisotropies, which encodes not only a wealth of cosmological information, but also provides a unique probe of the thermal history of the Universe during the time when the first stars and galaxies formed. In addition, the Planck sky surveys produced a wealth of information on the properties of extragalactic sources and on the dust and gas in our own Galaxy. The scientific objectives of Planck as conceived in 2005 (4 years before launch) were described in detail in the {{PlanckPapers|Bluebook}}.
  
 
The development of Planck began with two proposals presented to the
 
The development of Planck began with two proposals presented to the
European Space Agency (ESA) in May of 1993, for the Cosmic
+
European Space Agency (ESA) in May of 1993, for the [https://dms.cosmos.esa.int/cs/livelink/Open/3557509 Cosmic Background Radiation Anisotropy Satellite] (COBRAS)
Background Radiation Anisotropy Satellite (COBRAS)
+
and the [https://dms.cosmos.esa.int/cs/livelink/Open/3557510 Satellite for Measurement of Background Anisotropies] (SAMBA). Each of these proposed a payload formed by an offset
and the Satellite for Measurement of Background Anisotropies (SAMBA,
 
). Each of these proposed a payload formed by an offset
 
 
Gregorian telescope focussing light from the sky onto an array of
 
Gregorian telescope focussing light from the sky onto an array of
detectors (based on High Electron Mobility Transistor [HEMT] Low
+
detectors (based on high-electron-mobility transistor [HEMT] low
Noise Amplifiers for COBRAS and very low temperature bolometers for
+
noise amplifiers for COBRAS and very low temperature bolometers for
 
SAMBA) fed by corrugated horns. The two proposals were used by an
 
SAMBA) fed by corrugated horns. The two proposals were used by an
 
ESA-led team to design a payload where a single COBRAS-like
 
ESA-led team to design a payload where a single COBRAS-like
 
telescope fed two instruments, a COBRAS-like Low Frequency
 
telescope fed two instruments, a COBRAS-like Low Frequency
Instrument (LFI), and a SAMBA-like High Frequency Instrument (HFI)
+
Instrument (LFI), and a SAMBA-like High Frequency Instrument (HFI),
 
sharing a common focal plane. A period of study of this concept
 
sharing a common focal plane. A period of study of this concept
 
culminated in the selection by ESA in 1996 of the COBRAS/SAMBA
 
culminated in the selection by ESA in 1996 of the COBRAS/SAMBA
satellite (described in the so-called ``Redbook")
+
satellite (described in the so-called {{PlanckPapers|Redbook}})
 
into its programme of scientific satellites. At the time of
 
into its programme of scientific satellites. At the time of
 
selection the launch of COBRAS/SAMBA was expected to be in 2003.
 
selection the launch of COBRAS/SAMBA was expected to be in 2003.
Shortly after the mission was approved, it was renamed in honor of
+
Shortly after the mission was approved, it was renamed in honour of
the German scientist Max Planck (1858-1947), winner of the Nobel
+
the German scientist [https://www.cosmos.esa.int/web/planck/max-planck Max Planck] (1858-1947), winner of the Nobel
 
Prize for Physics in 1918.
 
Prize for Physics in 1918.
  
 
Shortly after its selection, the  development of Planck was joined
 
Shortly after its selection, the  development of Planck was joined
with that of ESA's Herschel Space Telescope, based on a number of
+
with that of ESA's [https://www.cosmos.esa.int/web/herschel Herschel Space Telescope], based on a number of
 
potential commonalities, the most important of which was that both
 
potential commonalities, the most important of which was that both
missions targeted orbits around the second Lagrangian point of the
+
missions targeted orbits around the second Lagrangian point of the
 
Sun-Earth system and could therefore share a single heavy launcher.
 
Sun-Earth system and could therefore share a single heavy launcher.
In practice the joint development has meant that a single ESA
+
In practice the joint development meant that a single ESA
engineering team has led the development of both satellites by a
+
engineering team led the development of both satellites by a
 
single industrial prime contractor, leading to the use of many
 
single industrial prime contractor, leading to the use of many
 
identical hardware and software subsystems in both satellites, and a
 
identical hardware and software subsystems in both satellites, and a
Line 80: Line 53:
 
competitively selected in early 2001. Thales Alenia Space France was
 
competitively selected in early 2001. Thales Alenia Space France was
 
supported by two major subcontractors: Thales Alenia Space Italy for
 
supported by two major subcontractors: Thales Alenia Space Italy for
the Service Module of both Planck and Herschel, and EADS Astrium
+
the Service Module of both Planck and Herschel; and EADS Astrium
GmbH for the Herschel Payload Module, and by many other industrial
+
GmbH for the Herschel Payload Module.  There were also contributions from many other industrial
subcontractors from all ESA member states.  
+
subcontractors from all ESA member states (the industrial team is described [http://sci.esa.int/planck/34787-industrial-team/  here] ).  
  
 
In early 1999, ESA selected two Consortia of scientific institutes to provide the two Planck
 
In early 1999, ESA selected two Consortia of scientific institutes to provide the two Planck
instruments which were part of the payload described in the Redbook: the Low Frequency Instrument
+
instruments that were part of the payload described in the {{PlanckPapers|Redbook}}: the Low Frequency Instrument
was developed by a consortium led by N. Mandolesi of the Istituto di Astrofisica Spaziale e Fisica
+
was developed by a consortium led by N. Mandolesi of the [http://www.iasfbo.inaf.it/en/ Istituto di Astrofisica Spaziale e Fisica
Cosmica (CNR) in Bologna (Italy); and the High Frequency Instrument by a consortium led by J.-L.
+
Cosmica] (CNR) in Bologna (Italy); and the High Frequency Instrument by a consortium led by J.-L.
Puget of the Institut d'Astrophysique Spatiale (CNRS) in Orsay (France). More than 40 European
+
Puget of the [https://www.ias.u-psud.fr/ Institut d'Astrophysique Spatiale] (CNRS) in Orsay (France).  
institutes, and some from the USA, have collaborated on the development and testing of these
 
instruments, and will continue to carry out their operation, as well as the ensuing data analysis
 
and initial scientific exploitation (see also Appendix A).
 
  
In early 2000, ESA and the Danish National Space Institute (DNSI) signed a Letter of Agreement for
+
In early 2000, ESA and the [http://www.space.dtu.dk/english Danish National Space Institute] (DNSI) signed a Letter of Agreement for
 
the provision of the two reflectors that are used in the Planck telescope. DNSI led a Consortium of
 
the provision of the two reflectors that are used in the Planck telescope. DNSI led a Consortium of
 
Danish institutes, which together with ESA subcontracted the development of the Planck reflectors to
 
Danish institutes, which together with ESA subcontracted the development of the Planck reflectors to
EADS Astrium GmbH (Friedrichshafen, D), who have manufactured the reflectors using state-of-the-art
+
EADS Astrium GmbH (Friedrichshafen, D), now part of the Airbus group, who have manufactured the reflectors using state-of-the-art
carbon fibre technology.
+
carbon-fibre technology.
 +
 
 +
In total, more than 40 European
 +
institutes, and some from the USA and Canada joined forces to constitute the [https://www.cosmos.esa.int/web/planck/planck-collaboration Planck Collaboration], and carry out the development, testing, and in-flight operations of these
 +
instruments, as well as the ensuing data analysis
 +
and initial scientific exploitation.
 +
 
 +
[[file:Planck_Logos.jpg|thumb|center|500px|The Planck Collaboration's institutes and agencies.]]
 +
 
  
The long development history of the Planck satellite culminated with its successful launch on 14
+
The development history of the Planck satellite is summarised [https://www.cosmos.esa.int/web/planck/mission-history here].
 +
It culminated with the successful launch of Planck and Herschel on 14
 
May 2009.
 
May 2009.
 +
After a period dedicated to Commissioning and Performance Verification, Planck started its planned survey observations on 12 August 2009.
 +
It carried on observing for a period of about 30 months, around twice the span originally required, and completed five full-sky surveys with both instruments. The Low Frequency Instrument (LFI), which was able to work at higher temperatures than HFI,  continued to survey the sky for a large part of 2013, providing even more data to improve the final Planck results.
 +
The last command to the Planck satellite was sent on the 23 October 2013, marking the end of operations.
 +
 +
<!-- [[file:PlanckMissionTimelineV2.png|thumb|480px|Timeline of the Planck operations and archiving.]]  -->
 +
 +
== The Planck data products and papers ==
 +
 +
The Data Products of Planck have been released in four different stages of increasing scope and quality.
 +
 +
* The first set of scientific data, the Early Release Compact Source Catalogue (ERCSC; {{PlanckPapers|planck2011-1-10}}), was published in January 2011. At the same time, a set of 26 papers related to astrophysical foregrounds was published in a special issue of Astronomy and Astrophysics (Vol. 536, 2011), among which there is an overview paper ({{PlanckPapers|planck2011-1-1}}).
 +
* The second set of data products (sometimes referred to as Planck Release 1 or “PR1,” because it was the first release of cosmologically useful data) was based on data acquired during the so-called nominal mission, i.e. from start of routine operations to 28 November 2010. These products were based on temperature analysis of the whole sky, and were released in March of 2013. The data and associated scientific results are described in a set of 32 papers in another special issue of A&A (Vol. 571, 2014), among which there is another overview ({{PlanckPapers|planck2013-p01}}).
 +
* The third set of data products (and second set of cosmological data, hence “PR2”) and scientific results released by Planck, was based on the data acquired during the complete Planck mission from 12 August 2009 to 23 October 2013, and hereafter referred to as the “2015 products.” They are based on both temperature and polarization analysis of the entire sky, and were released between February and July 2015. The data and associated scientific results are described in a set of 28 papers published in a third special issue of A&A (Vol. 594, 2016). Again there is an overview paper paper ({{PlanckPapers|planck2014-a01}}).
 +
* The fourth set of scientific data (and third set of cosmological data, hence "PR3") was based on the full mission, focussing on inclusion of the polarization data.  The data and associated scientific results are described in a series of 11 papers, including a final "Legacy" which also includes an overview of this release ({{PlanckPapers|planck2016-l01}}.
 +
 +
In addition to the above listed four groups of data-release-related papers, the Planck Collaboration has published more than 50 “Intermediate” papers containing further astrophysical investigations. These papers are usually based on data products that are either already public or about to become public at the time of publication.
 +
 +
All of the Planck Collaboration papers are listed in and can be downloaded from [https://www.cosmos.esa.int/web/planck/publications]. At the current time, we encourage people interested in an overview on Planck to start with the latest overview paper ({{PlanckPapers|planck2016-l01}}), and follow references to more specific areas of interest.
 +
 +
== The Planck Legacy Archive ==
 +
 +
The [http://pla.esac.esa.int/ Planck Legacy Archive] (PLA) contains all public products originating from the Planck mission, and provides an online interface to select and retrieve them. The majority of the scientific data products from Planck have been produced by the LFI and HFI Data Processing Centres on behalf of the [[Planck Collaboration|Planck Collaboration]].
 +
 +
The data products distributed by PLA are classified into the following categories.
 +
* "Timelines" contain time series of data acquired. The types of data provided are:
 +
** "semi-raw timelines" containing data samples per detector, which have been very minimally processed after retrieval from the satellite;
 +
** "calibrated timelines" containing data samples per detector after cleaning and calibration.
 +
* "Rings" are timelines that have been binned into individual periods of fixed spin axis pointing. Each ring traces a quasi-large circle on the sky.
 +
* "Maps" are generally all-sky maps in HEALPix format. There are two major types of Planck maps:
 +
** "frequency maps" are maps as observed at one of the nine frequency channels of Planck, containing at least temperature, and in the later versions also polarization, and existing in many varieties of maps, depending on which detectors and/or time coverage is included in their production;
 +
** "component maps" are maps of diffuse emission of specific physical components, including the CMB, Galactic, and extragalactic foregrounds, which are constructed from Planck observations using different methods.
 +
* The "Likelihood code" is the software used by the Planck Collaboration to extract the values of cosmological parameters from the Planck data. The code is bundled with the data set (from Planck and other experiments) that it needs to run.
 +
* "Catalogues" contain lists of compact or point-like sources extracted from the Planck maps. The basic Planck catalogues have been extracted without regard to the type of source, but some specialized lists of specific source types are also available.
 +
* "Cosmological data" contain results of some of the cosmological analyses that formed the main objective of Planck, i.e. CMB angular power spectra, cosmological model parameters, etc.
 +
 +
In addition to the above, the PLA also includes a wide variety of additional products:
 +
* external scientific data that were used in the generation of Planck products;
 +
* data characterizing the Planck payload;
 +
* operational data.
 +
 +
All of the Planck products are labelled according to their release: ERCSC-A 2012; PR1 2013; PR2 2015; and PR3 2018. In addition, the product most recommended for use is labelled as the "Legacy" product. The PLA interface allows the user to search the Archive using a wide variety of parameters. It also provides the possibility to extract parts of the products, e.g. a section of the sky, and in some cases to modify them. The PLA also makes it easy to transfer products to generic data analysis tools for further analysis, e.g. Aladin for maps, and Topcat for catalogues.
 +
 +
Finally, the PLA also contains some selected data products that are based on Planck data, but have not been produced by the Planck Collaboration. These data are labelled as "Community" products.
 +
 +
All the PLA products can be accessed via its [http://pla.esac.esa.int/pla/#home graphical interface]. Some of the products can also be extracted via a [http://pla.esac.esa.int/pla/#aio machine interface].
 +
 +
== This Explanatory Supplement ==
 +
 +
This Explanatory Supplement (ES) has been built by the Planck Collaboration and the Planck Science Office. It contains:
 +
* general technical information on the Planck satellite, its payload, and its operations;
 +
* specific information for each of the products being distributed by the PLA.
 +
 +
The ES can be accessed online independently or can be called directly from the PLA interface (in this case it will direct the user to the appropriate sections). In general, it will display descriptions appropriate to the "Legacy" products. However,  descriptions specific for each of the four Planck releases can be found at the end of each of the ES sections; the background colour of the ES page identifies the release it refers to.
 +
 +
We emphasize that the ES  contains a bare minimum of necessary information on the data products. We strongly recommend that users read the scientific papers by the Planck Collaboration that are closest to their own application. Those papers contain the most relevant and useful information on the quality and limitations of the Planck products, which has often not been fully captured in the ES.
  
 
==For more information==
 
==For more information==
  
A complete overview of the Planck mission and its science programme can be found in the [http://www.sciops.esa.int/SA/PLANCK/docs/Bluebook-ESA-SCI%282005%291_V2.pdf Blue Book].
+
A complete list of Planck publications can be found [http://www.sciops.esa.int/index.php?project=PLANCK&page=Planck_Published_Papers here].
  
More details on the Planck mission performance can be found in {{BibCite|planck2011-1-1}}, .
+
Suggestions or questions should be sent to the [https://support.cosmos.esa.int/pla/ Helpdesk].
 +
 
 +
==Acknowledgments==
 +
The development of Planck has been supported by: ESA; CNES and
 +
CNRS/INSU-IN2P3-INP (France); ASI, CNR, and INAF (Italy); NASA and DoE (USA);
 +
STFC and UKSA (UK); CSIC, MICINN, JA, and RES (Spain); Tekes, AoF, and CSC
 +
(Finland); DLR and MPG (Germany); CSA (Canada); DTU Space (Denmark); SER/SSO
 +
(Switzerland); RCN (Norway); SFI (Ireland); FCT/MCTES (Portugal); and PRACE
 +
(EU). A description of the Planck Collaboration and a list of its members,
 +
including the technical or scientific activities in which they have been
 +
involved, can be found at  [http://www.cosmos.esa.int/web/planck/planck-collaboration this site].
  
A complete list of Planck publications can be found [http://www.sciops.esa.int/index.php?project=PLANCK&page=Planck_Published_Papers here].
 
  
 
==References==
 
==References==
Line 114: Line 157:
 
   
 
   
  
 
[[Category:Introduction|001]]
 
 
[[Category:PSOBook]]
 
[[Category:PSOBook]]

Latest revision as of 12:43, 17 July 2018


The Planck mission[edit]

Planck is a mission of the European Space Agency - ESA. The Planck satellite carried instruments provided by two scientific Consortia funded by ESA member states (in particular the lead countries: France and Italy) with contributions from NASA (USA), and telescope reflectors provided in a collaboration between ESA and a scientific Consortium led and funded by Denmark.

Planck was conceived in 1992, in the wake of the release of the results from the Cosmic Background Explorer (COBE) satellite, notably its measurement of the shape of the spectrum of the cosmic microwave background (CMB), and its detection of the spatial anisotropies of the temperature of the CMB. The latter result in particular led to an explosion in the number of ground-based and suborbital experiments dedicated to mapping of the anisotropies, and to proposals for space experiments both in Europe and the USA.

The main objective of Planck was to measure the spatial anisotropies of the temperature of the CMB, with an accuracy set by fundamental astrophysical limits. Its level of performance enabled Planck to extract essentially all the information in the CMB temperature anisotropies. Planck also measured to high accuracy the polarization of the CMB anisotropies, which encodes not only a wealth of cosmological information, but also provides a unique probe of the thermal history of the Universe during the time when the first stars and galaxies formed. In addition, the Planck sky surveys produced a wealth of information on the properties of extragalactic sources and on the dust and gas in our own Galaxy. The scientific objectives of Planck as conceived in 2005 (4 years before launch) were described in detail in the Bluebook[1].

The development of Planck began with two proposals presented to the European Space Agency (ESA) in May of 1993, for the Cosmic Background Radiation Anisotropy Satellite (COBRAS) and the Satellite for Measurement of Background Anisotropies (SAMBA). Each of these proposed a payload formed by an offset Gregorian telescope focussing light from the sky onto an array of detectors (based on high-electron-mobility transistor [HEMT] low noise amplifiers for COBRAS and very low temperature bolometers for SAMBA) fed by corrugated horns. The two proposals were used by an ESA-led team to design a payload where a single COBRAS-like telescope fed two instruments, a COBRAS-like Low Frequency Instrument (LFI), and a SAMBA-like High Frequency Instrument (HFI), sharing a common focal plane. A period of study of this concept culminated in the selection by ESA in 1996 of the COBRAS/SAMBA satellite (described in the so-called Redbook[2]) into its programme of scientific satellites. At the time of selection the launch of COBRAS/SAMBA was expected to be in 2003. Shortly after the mission was approved, it was renamed in honour of the German scientist Max Planck (1858-1947), winner of the Nobel Prize for Physics in 1918.

Shortly after its selection, the development of Planck was joined with that of ESA's Herschel Space Telescope, based on a number of potential commonalities, the most important of which was that both missions targeted orbits around the second Lagrangian point of the Sun-Earth system and could therefore share a single heavy launcher. In practice the joint development meant that a single ESA engineering team led the development of both satellites by a single industrial prime contractor, leading to the use of many identical hardware and software subsystems in both satellites, and a synergistic sharing of engineering skills and manpower. The industrial prime contractor, Thales Alenia Space France, was competitively selected in early 2001. Thales Alenia Space France was supported by two major subcontractors: Thales Alenia Space Italy for the Service Module of both Planck and Herschel; and EADS Astrium GmbH for the Herschel Payload Module. There were also contributions from many other industrial subcontractors from all ESA member states (the industrial team is described here ).

In early 1999, ESA selected two Consortia of scientific institutes to provide the two Planck instruments that were part of the payload described in the Redbook[2]: the Low Frequency Instrument was developed by a consortium led by N. Mandolesi of the [http://www.iasfbo.inaf.it/en/ Istituto di Astrofisica Spaziale e Fisica Cosmica] (CNR) in Bologna (Italy); and the High Frequency Instrument by a consortium led by J.-L. Puget of the Institut d'Astrophysique Spatiale (CNRS) in Orsay (France).

In early 2000, ESA and the Danish National Space Institute (DNSI) signed a Letter of Agreement for the provision of the two reflectors that are used in the Planck telescope. DNSI led a Consortium of Danish institutes, which together with ESA subcontracted the development of the Planck reflectors to EADS Astrium GmbH (Friedrichshafen, D), now part of the Airbus group, who have manufactured the reflectors using state-of-the-art carbon-fibre technology.

In total, more than 40 European institutes, and some from the USA and Canada joined forces to constitute the Planck Collaboration, and carry out the development, testing, and in-flight operations of these instruments, as well as the ensuing data analysis and initial scientific exploitation.

The Planck Collaboration's institutes and agencies.


The development history of the Planck satellite is summarised here. It culminated with the successful launch of Planck and Herschel on 14 May 2009. After a period dedicated to Commissioning and Performance Verification, Planck started its planned survey observations on 12 August 2009. It carried on observing for a period of about 30 months, around twice the span originally required, and completed five full-sky surveys with both instruments. The Low Frequency Instrument (LFI), which was able to work at higher temperatures than HFI, continued to survey the sky for a large part of 2013, providing even more data to improve the final Planck results. The last command to the Planck satellite was sent on the 23 October 2013, marking the end of operations.


The Planck data products and papers[edit]

The Data Products of Planck have been released in four different stages of increasing scope and quality.

  • The first set of scientific data, the Early Release Compact Source Catalogue (ERCSC; Planck-Early-VII[3]), was published in January 2011. At the same time, a set of 26 papers related to astrophysical foregrounds was published in a special issue of Astronomy and Astrophysics (Vol. 536, 2011), among which there is an overview paper (Planck-Early-I[4]).
  • The second set of data products (sometimes referred to as Planck Release 1 or “PR1,” because it was the first release of cosmologically useful data) was based on data acquired during the so-called nominal mission, i.e. from start of routine operations to 28 November 2010. These products were based on temperature analysis of the whole sky, and were released in March of 2013. The data and associated scientific results are described in a set of 32 papers in another special issue of A&A (Vol. 571, 2014), among which there is another overview (Planck-2013-I[5]).
  • The third set of data products (and second set of cosmological data, hence “PR2”) and scientific results released by Planck, was based on the data acquired during the complete Planck mission from 12 August 2009 to 23 October 2013, and hereafter referred to as the “2015 products.” They are based on both temperature and polarization analysis of the entire sky, and were released between February and July 2015. The data and associated scientific results are described in a set of 28 papers published in a third special issue of A&A (Vol. 594, 2016). Again there is an overview paper paper (Planck-2015-A01[6]).
  • The fourth set of scientific data (and third set of cosmological data, hence "PR3") was based on the full mission, focussing on inclusion of the polarization data. The data and associated scientific results are described in a series of 11 papers, including a final "Legacy" which also includes an overview of this release (Planck-2020-A1[7].

In addition to the above listed four groups of data-release-related papers, the Planck Collaboration has published more than 50 “Intermediate” papers containing further astrophysical investigations. These papers are usually based on data products that are either already public or about to become public at the time of publication.

All of the Planck Collaboration papers are listed in and can be downloaded from [1]. At the current time, we encourage people interested in an overview on Planck to start with the latest overview paper (Planck-2020-A1[7]), and follow references to more specific areas of interest.

The Planck Legacy Archive[edit]

The Planck Legacy Archive (PLA) contains all public products originating from the Planck mission, and provides an online interface to select and retrieve them. The majority of the scientific data products from Planck have been produced by the LFI and HFI Data Processing Centres on behalf of the Planck Collaboration.

The data products distributed by PLA are classified into the following categories.

  • "Timelines" contain time series of data acquired. The types of data provided are:
    • "semi-raw timelines" containing data samples per detector, which have been very minimally processed after retrieval from the satellite;
    • "calibrated timelines" containing data samples per detector after cleaning and calibration.
  • "Rings" are timelines that have been binned into individual periods of fixed spin axis pointing. Each ring traces a quasi-large circle on the sky.
  • "Maps" are generally all-sky maps in HEALPix format. There are two major types of Planck maps:
    • "frequency maps" are maps as observed at one of the nine frequency channels of Planck, containing at least temperature, and in the later versions also polarization, and existing in many varieties of maps, depending on which detectors and/or time coverage is included in their production;
    • "component maps" are maps of diffuse emission of specific physical components, including the CMB, Galactic, and extragalactic foregrounds, which are constructed from Planck observations using different methods.
  • The "Likelihood code" is the software used by the Planck Collaboration to extract the values of cosmological parameters from the Planck data. The code is bundled with the data set (from Planck and other experiments) that it needs to run.
  • "Catalogues" contain lists of compact or point-like sources extracted from the Planck maps. The basic Planck catalogues have been extracted without regard to the type of source, but some specialized lists of specific source types are also available.
  • "Cosmological data" contain results of some of the cosmological analyses that formed the main objective of Planck, i.e. CMB angular power spectra, cosmological model parameters, etc.

In addition to the above, the PLA also includes a wide variety of additional products:

  • external scientific data that were used in the generation of Planck products;
  • data characterizing the Planck payload;
  • operational data.

All of the Planck products are labelled according to their release: ERCSC-A 2012; PR1 2013; PR2 2015; and PR3 2018. In addition, the product most recommended for use is labelled as the "Legacy" product. The PLA interface allows the user to search the Archive using a wide variety of parameters. It also provides the possibility to extract parts of the products, e.g. a section of the sky, and in some cases to modify them. The PLA also makes it easy to transfer products to generic data analysis tools for further analysis, e.g. Aladin for maps, and Topcat for catalogues.

Finally, the PLA also contains some selected data products that are based on Planck data, but have not been produced by the Planck Collaboration. These data are labelled as "Community" products.

All the PLA products can be accessed via its graphical interface. Some of the products can also be extracted via a machine interface.

This Explanatory Supplement[edit]

This Explanatory Supplement (ES) has been built by the Planck Collaboration and the Planck Science Office. It contains:

  • general technical information on the Planck satellite, its payload, and its operations;
  • specific information for each of the products being distributed by the PLA.

The ES can be accessed online independently or can be called directly from the PLA interface (in this case it will direct the user to the appropriate sections). In general, it will display descriptions appropriate to the "Legacy" products. However, descriptions specific for each of the four Planck releases can be found at the end of each of the ES sections; the background colour of the ES page identifies the release it refers to.

We emphasize that the ES contains a bare minimum of necessary information on the data products. We strongly recommend that users read the scientific papers by the Planck Collaboration that are closest to their own application. Those papers contain the most relevant and useful information on the quality and limitations of the Planck products, which has often not been fully captured in the ES.

For more information[edit]

A complete list of Planck publications can be found here.

Suggestions or questions should be sent to the Helpdesk.

Acknowledgments[edit]

The development of Planck has been supported by: ESA; CNES and CNRS/INSU-IN2P3-INP (France); ASI, CNR, and INAF (Italy); NASA and DoE (USA); STFC and UKSA (UK); CSIC, MICINN, JA, and RES (Spain); Tekes, AoF, and CSC (Finland); DLR and MPG (Germany); CSA (Canada); DTU Space (Denmark); SER/SSO (Switzerland); RCN (Norway); SFI (Ireland); FCT/MCTES (Portugal); and PRACE (EU). A description of the Planck Collaboration and a list of its members, including the technical or scientific activities in which they have been involved, can be found at this site.


References[edit]

  1. The Planck Bluebook, The Scientific Programme of Planck, Planck Collaboration, 2005, ESA Publication ESA-SCI(2005)01
  2. 2.02.1 The Planck Redbook, Report on the Phase A Study of COBRAS/SAMBA, 1996, ESA Publication D-SCI(96)3
  3. Planck early results. VII. The Early Release Compact Source Catalogue, Planck Collaboration VII, A&A, 536, A7, (2011).
  4. Planck early results. I. The Planck mission, Planck Collaboration I, A&A, 536, A1, (2011).
  5. Planck 2013 results. I. Overview of Products and Results, Planck Collaboration, 2014, A&A, 571, A1.
  6. Planck 2015 results. I. Overview of products and results, Planck Collaboration, 2016, A&A, 594, A1.
  7. 7.07.1 Planck 2018 results. I. Overview, and the cosmological legacy of Planck, Planck Collaboration, 2020, A&A, 641, A1.

European Space Agency

Cosmic Microwave background

High Electron Mobility Transistor

(Planck) Low Frequency Instrument

(Planck) High Frequency Instrument

Early Release Compact Source Catalog

Planck Legacy Archive

(Hierarchical Equal Area isoLatitude Pixelation of a sphere, <ref name="Template:Gorski2005">HEALPix: A Framework for High-Resolution Discretization and Fast Analysis of Data Distributed on the Sphere, K. M. Górski, E. Hivon, A. J. Banday, B. D. Wandelt, F. K. Hansen, M. Reinecke, M. Bartelmann, ApJ, 622, 759-771, (2005).

Explanatory Supplement

Solar System Object