Difference between revisions of "DatesObs"
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=== Overview === | === Overview === | ||
| − | The DATESOBS files are not official Planck products but | + | The DATESOBS files are not official Planck products but have been made available for the convenience of the community. They contain timing information gridded by HEALPIX pixel and sampled by UTC day for investigation of inter-survey source variability and comparison with external observations. |
=== File Format === | === File Format === | ||
| − | There are 27 files for all combinations of instrument | + | There are 27 files for all combinations of the 9 instrument bands and 3 surveys. The files themselves are: |
* FITS format, with data in the first extension | * FITS format, with data in the first extension | ||
* RING-ordered HEALPIX | * RING-ordered HEALPIX | ||
| Line 10: | Line 10: | ||
They contain two fields: | They contain two fields: | ||
| − | * DATESOBS - list of UTC days on which the pixel was observed | + | * DATESOBS - string - Comma-separated list of UTC days in YYMMDD format on which the pixel was observed |
| − | * NUMOBS - The number of UTC days on which the pixel was observed. | + | * NUMOBS - integer - The number of UTC days on which the pixel was observed |
| + | |||
| + | Unobserved pixels have been left blank. | ||
| + | |||
| + | === Generation === | ||
| + | |||
| + | The DATESOBS files were generated by projecting the line of sight of each detector on the sky for each observing ring starting on a UTC day. Inputs were the satellite spin-axis, the opening angle of each detector, and the per-survey hit-map in order to mask unobserved data (mainly planet crossings, the survey_3_partial DATESOBS files are unmasked as no survey_3 maps are available). Position is thus accurate to nearest pixel center and rings which cross midnight UTC are only counted the day in which they begin. | ||
Revision as of 00:43, 12 March 2013
Overview[edit]
The DATESOBS files are not official Planck products but have been made available for the convenience of the community. They contain timing information gridded by HEALPIX pixel and sampled by UTC day for investigation of inter-survey source variability and comparison with external observations.
File Format[edit]
There are 27 files for all combinations of the 9 instrument bands and 3 surveys. The files themselves are:
- FITS format, with data in the first extension
- RING-ordered HEALPIX
- NSIDE 1024 for LFI, and 2048 for HFI
They contain two fields:
- DATESOBS - string - Comma-separated list of UTC days in YYMMDD format on which the pixel was observed
- NUMOBS - integer - The number of UTC days on which the pixel was observed
Unobserved pixels have been left blank.
Generation[edit]
The DATESOBS files were generated by projecting the line of sight of each detector on the sky for each observing ring starting on a UTC day. Inputs were the satellite spin-axis, the opening angle of each detector, and the per-survey hit-map in order to mask unobserved data (mainly planet crossings, the survey_3_partial DATESOBS files are unmasked as no survey_3 maps are available). Position is thus accurate to nearest pixel center and rings which cross midnight UTC are only counted the day in which they begin.
Universal Time Coordinate(d)
Flexible Image Transfer Specification
(Planck) Low Frequency Instrument
(Planck) High Frequency Instrument
