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Simultaneous observations with Planck

Simultaneous multi-frequency observations of variables, non-variable, and candidate variable sources are a valuable data for Astronomy. Astronomers interested in simultaneous observations with Planck will find here the necessary data and information for planning their activity.

Planck's survey

Planck surveys twice the full sky over a 15 months period, and its first all-sky survey has started on August 13th 2009. From its orbit around L2, Planck observes the sky by continuously scanning nearly great circles on the celestial sphere, and periodically shifting the spin axis to remain anti-Sun throughout the year. The Figure below is an illustration of Planck's surveying strategy. The telescope field-of-view rotates at 1 rpm, while its spins axis regularly moves, about 2 arcmin/hour in ecliptic longitude, to remain anti-Sun.

The Planck's telescope focuses radiation from the sky onto its focal plane, which is shared by two instruments: The Low Frequency Instrument (LFI), an array of radiometers covering three frequency bands from 30 to 70 GHz, and the High Frequency Instrument (HFI), an array of bolometers covering six frequency bands from 100 to 857 GHz. A layout of its focal plane on the sky is displayed bellow.

Even though CMB anisotropies are Planck's main target, its capabilities are also suitable for observations of cold objects, as well as those with bright free-free radiation from ionized gas. Planck will detect galactic and extragalactic objects such as HII regions, cold cores in molecular clouds, flat-spectrum radio sources (like blazars) at low frequencies, and redshifted galaxies (whose dust emission peaks in the high frequencies). An all-sky catalogue of compact and point sources, extracted from Planck's data, will be released to the scientific community approximately 10 months after the first full sky survey is finished, in time for the first post-launch call for Herschel observing proposals. This Planck scientific product, named the Early Release Compact Source Catalogue (ERCSC), will provide useful information about galactic and extragalactic sources, and it will be the first all-sky catalogue at sub-mm wavelengths.

Planck's pointing data and documents

The necessary information to plan a simultaneous observations with Planck, and predict when an object will be observable, is provided by the following data:

The Planned Pointing List (PPL), which contains a sequence of pointings for the Planck's spin axis covering about one month period of the survey.

[Download PPL covering period from 27AUG2009 to 01OCT2009]

[Download PPL covering period from 01OCT2009 to 01NOV2009]

[Download PPL covering period from 01NOV2009 to 01DEC2009]

[Download PPL covering period from 01DEC2009 to 01JAN2010]

[Download PPL covering period from 01JAN2010 to 01FEB2010]

[Download PPL covering period from 01FEB2010 to 14FEB2010]

[Download PPL covering period from 14FEB2010 to 01MAR2010]

[Download PPL covering period from 01MAR2010 to 01APR2010]

[Download PPL covering period from 01APR2010 to 01MAY2010]

[Download PPL covering period from 01MAY2010 to 01JUN2010]

[Download PPL covering period from 01JUN2010 to 01JUL2010]

[Download PPL covering period from 01JUL2010 to 01AUG2010]

[Download PPL covering period from 01AUG2010 to 14AUG2010]

[Download PPL covering period from 14AUG2010 to 25AUG2010]

[Download PPL covering period from 25AUG2010 to 16SEP2010]

[Download PPL covering period from 16SEP2010 to 01OCT2010]

[Download PPL covering period from 01OCT2010 to 01NOV2010]

[Download PPL covering period from 01NOV2010 to 01DEC2010]

[Download PPL covering period from 01DEC2010 to 16DEC2010]

[Download PPL covering period from 16DEC2010 to 01JAN2011]

[Download PPL covering period from 01JAN2011 to 14FEB2011]

[Download PPL covering period from 14FEB2011 to 01APR2011]

[Download PPL covering period from 01APR2011 to 01MAY2011]

[Download PPL covering period from 01MAY2011 to 01JUN2011]

[Download PPL covering period from 01JUN2011 to 01JUL2011]

[Download PPL covering period from 01JUL2011 to 30JUL2011]

[Download PPL covering period from 29JUL2011 to 01SEP2011]

[Download PPL covering period from 01SEP2011 to 01OCT2011]

[Download PPL covering period from 01OCT2011 to 01NOV2011]

[Download PPL covering period from 01NOV2011 to 08DEC2011]

[Download PPL covering period from 01DEC2011 to 07DEC2011] (it replaces the last week of previous PPL)

[Download PPL covering period from 08DEC2011 to 16DEC2011]

[Download PPL covering period from 16DEC2011 to 01JAN2012]

[Download PPL covering period from 01JAN2012 to 08JAN2012]

[Download PPL covering period from 08JAN2012 to 15JAN2012]

[Download PPL covering period from 15JAN2012 to 01FEB2012]

[Download PPL covering period from 01FEB2012 to 26FEB2012]

[Download PPL covering period from 26FEB2012 to 16MAR2012]

[Download PPL covering period from 24JAN2012 to 01FEB2012] (it replaces previous planning)

[Download PPL covering period from 31JAN2012 to 16MAR2012] (it replaces previous planning)

[Download PPL covering period from 16MAR2012 to 01APR2012]

[Download PPL covering period from 01APR2012 to 01MAY2012]

[Download PPL covering period from 01MAY2012 to 01JUN2012]

[Download PPL covering period from 01JUN2012 to 01JUL2012]

[Download PPL covering period from 01JUL2012 to 01AUG2012]

[Download PPL covering period from 01AUG2012 to 01SEP2012]

[Download PPL covering period from 01SEP2012 to 01OCT2012]

[Download PPL covering period from 01OCT2012 to 01NOV2012]

[Download PPL covering period from 01NOV2012 to 01DEC2012]

[Download PPL covering period from 01DEC2012 to 01JAN2013]

[Download PPL covering period from 01JAN2013 to 30JAN2013]

[Download PPL covering period from 30JAN2013 to 28FEB2013]

[Download PPL covering period from 28FEB2013 to 01APR2013]

[Download PPL covering period from 01APR2013 to 01MAY2013]

[Download PPL covering period from 01MAY2013 to 01JUN2013]

[Download PPL covering period from 01JUN2013 to 01JUL2013]

[Download PPL covering period from 01JUL2013 to 01AUG2013]

[Download PPL covering period from 01AUG2013 to 01SEP2013]

[Download PPL covering period from 01SEP2013 to 04OCT2013]

[Download PPL covering period from 15SEP2013 to 04OCT2013] (it replaces part of previous planning)

[Download PPL covering period from 04OCT2013 to 23OCT2013]

The Long Term Preprogrammed Pointing List (LTPPL), which provides about one year of planned pointings, and is based on the best survey information available at the time.

[Download LTPPL covering period from 01SEP2011 to 12JAN2012]

[Download PPL and LTPPL documentation]

The Spacecraft Instrument Alignment Matrix (SIAM), which gives the alignment data of the Planck instruments with respect to the spacecraft functional reference frame

[Download latest SIAM]

[Download SIAM documentation]

By combining the position of the spin axis at every pointing (as provided by the PPL) with the angle of each receiver with respect to the spin axis (as provided by the SIAM) it is possible to identify the region of the sky swept by each aligned set of Planck receivers. A source will be observable by a Planck receiver if it is within a beam unit strip during the full rotation of the satellite around its spin axis.  For periods not yet covered by the PPL, one should use the LTPPL instead.

An animation of the Planck sky coverage based on LTPPL data, with a NASA/WMAP image as a background, has been produced by Chris North, Cardiff University, and it is available on a video sharing website.

Note: The PPL and LTPPL are planning files, and the actual executed pointings may differ from their contents. The actual executed pointings may differ from the pointings in the PPL but it is not expected that we will see large differences between planned and executed pointings although that cannot be completely ruled out; the corresponding accuracy of the LTPPL is lower because of the longer look-forward timescale. The SIAM contains best knowledge which will evolve through the lifetime of Planck. Currently, the relative placement of the beams is known to a fraction of the smallest beam size, i.e. of order 2 arcminutes. Its absolute location with respect to the spin axis will change during the mission and is currently provided with an accuracy of about 30 arcminutes. The current SIAM is based on ground measurements. As calibrations sources cross the focal plane the accuracy of this information will improve and the SIAM will be updated.

The Planck On-Flight Forecaster (POFF)

The Planck On-Flight Forecaster (POFF) is a tool that reads the PPL and SIAM data and predicts when a user-provided list of positions in the sky will be observable by the Planck receivers (Massardi & Burigana 2009). The POFF is successfully used to plan simultaneous observation of known objects within the Planck collaboration, and it is now available for external observers.

Note: The POFF is not an official Planck product, but it is produced on a best-effort basis by individual members of the Planck collaboration.

To know more

For more details, please, refer to the following work:

The Planck Collaboration; [The Scientific Programme of Planck], 2006, eprint arXiv:astro-ph/0604069

Dupac, X.; Tauber, J.; Scanning strategy for mapping the Cosmic Microwave Background anisotropies with Planck, 2005, A&A, 430, 363

Massardi, M.; Burigana, C.; The Planck On-Flight Forecaster (POFF), 2009, eprint arXiv:0911.5056

The above information should be sufficient to determine where Planck will be pointing at any given time. Further questions or requests for specific information may be directed to e-mail a request, quoting Simultaneous observations with Planck in the subject.


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This page was first created on 31 August, 2009 and was last updated on 18 September, 2013.
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