Difference between revisions of "DatesObs"
| Line 10: | Line 10: | ||
They contain two fields: | They contain two fields: | ||
| − | * DATESOBS - string - | + | * DATESOBS - string - comma-separated list of UTC days in YYMMDD format on which the pixel was observed |
| − | * NUMOBS - integer - | + | * NUMOBS - integer - the number of UTC days on which the pixel was observed |
Unobserved pixels have been left blank. | Unobserved pixels have been left blank. | ||
| Line 17: | Line 17: | ||
=== Generation === | === Generation === | ||
| − | The DATESOBS files were generated by projecting the line-of-sight of each detector on the sky for each | + | The DATESOBS files were generated by projecting the line-of-sight of each detector on the sky for each integration ring on a ring-by-ring basis. Inputs were the satellite spin-axis and the opening angle of each detector. Position is thus accurate to nearest pixel center and timing to the start of each ring - integration over midnight are only counted for the day in which they begin. |
| − | Note no beam information was used, just closest line-of-sight. The list of dates within a beam width is thus the union of all | + | Note no beam information was used, just closest line-of-sight. The list of dates within a beam width is thus the union of the date information for all pixels within the appropriate area. |
Pixels were counted observed if hit by a single detector within each instrument band; there is no consideration of intra-band coverage. | Pixels were counted observed if hit by a single detector within each instrument band; there is no consideration of intra-band coverage. | ||
Finally the data has been masked by the per-survey frequency 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. | Finally the data has been masked by the per-survey frequency 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. | ||
Revision as of 01:13, 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 split by survey, gridded by HEALPIX pixel, and sampled by UTC day for investigation of inter-survey source variability, comparison with external observations, and understanding of the survey strategy.
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 integration ring on a ring-by-ring basis. Inputs were the satellite spin-axis and the opening angle of each detector. Position is thus accurate to nearest pixel center and timing to the start of each ring - integration over midnight are only counted for the day in which they begin.
Note no beam information was used, just closest line-of-sight. The list of dates within a beam width is thus the union of the date information for all pixels within the appropriate area.
Pixels were counted observed if hit by a single detector within each instrument band; there is no consideration of intra-band coverage.
Finally the data has been masked by the per-survey frequency 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.
Universal Time Coordinate(d)
Flexible Image Transfer Specification
(Planck) Low Frequency Instrument
(Planck) High Frequency Instrument
