SCUBA2_MAPSTATSThe Picard recipe SCUBA2_MAPSTATS estimates the RMS and NEFD for a given observation.
The average NEP is calculated from the QL pipeline log file (log.nep) corresponding to the date and
wavelength. The FCF (either from the file or the standard value) and mean transmission over the observation is
used to convert this to a zenith NEFD (NEFD).
The input images are cropped to the given size (as specified in the FITS headers or via the MAP_HEIGHT and MAP_WIDTH recipe parameters) before the mean exposure time is derived, along with the mean/median noise and NEFD (RMS and NEFDs).
The parameters written out to log.mapstats are listed below:
| Parameter | Description |
| UT | UT date including day fraction |
| HST | HST date and time stamp |
| Obs | observation number |
| Source | object name |
| Mode | observation mode (either daisy or pong) |
| FILTER | filter (wavelength) |
| El | mean elevation of observation |
| Airmass | mean airmass of observation |
| Trans | mean line-of-sight transmission |
| Tau225 | mean zenith optical depth at 225 GHz, derived from WVM |
| Tau | mean zenith optical depth at observed frequency |
| telapsed | elapsed time of observation in seconds |
| texp | mean exposure time, derived from EXP_TIME NDF component (sec) |
| rms | RMS noise in map, obtained from median of error array |
| rms_units | RMS units |
| nefd | NEFD derived from combination of variance and exposure time images |
| nefd_units | NEFD units |
| RA | Right Ascension |
| Dec | Declination |
| mapsize | size (requested diameter) of input map (arcsec) |
| pixscale | pixel scale in arcsec |
| project | project ID |
| recipe | reduction recipe used |
| filename | name of input file |
Although the output file log.mapstats can be viewed with any text editor, it is useful to read this file with
Topcat:
After running the command above, click on “Views” Then “Table Data” to display the table.