SPIRE Spectral Calibrators - Herschel
SPIRE Spectral Calibrators
During Herschel’s mission the SPIRE Spectrometer took repeated observations of several calibration sources. Full details of the systematic programme of calibration observation can be found in Hopwood et al. (2015). Some of the data used in that paper received post-pipeline processing and where the quality of the data were improved (over the standard products available in the Herschel Science Archive, HSA), therefore these are provided as HPDPs.
Description of HPDP
Point-source calibrated high resolution SPIRE Spectrometer spectra of the primary and secondary calibration sources, which have received post-pipeline correction.
There are up to three corrections for each observation.
- Correction for pointing offset, where the offset was assessed using the relative method described in Valtchanov et al. 2014.
- Correction for partial extent, which was corrected using the Semi Extended Correction Tool in HIPE.
- Removal of high-background emission, which was subtracted using the average spectra of off-axis detectors.
The final, corrected spectra are available in the Herschel legacy HPDP area.
The CSV file “observationList.csv” lists the source name, observation and which of the corrections have been applied to the HPDP as
- “pointingOffsetCorr” for pointing offset correction
- “SECT” for semi-extended morphology correction
- “backgroundSubtracted” where background emission has been subtracted
These HPDPs were reduced with HIPE version 13, using spire_cal_13_1 and are presented in the standard pipeline generation final product form for sparse-mode SPIRE Spectrometer observations.
The data provided were all observed in high-resolution mode and are point-source calibrated in units of Jansky. Any low resolution or extended-source calibrated data used in Hopwood et al. (2015) are not provided, as there were significant improvements to the associated calibration in HIPE version 14 (see Marchili et al. 2017 and Valtchanov et al. 2018).
Each HPDP is provided as a gzipped FITS file, which are named as follows.
The prefix convention is:
“OBSID_spectrometerCalibrator_”, where OBSID is the observation ID number.
The suffix of the file depends on which of the three corrections have been applied:
- “pointOffCorr” indicates correction for pointing offset.
- “extentCorr” indicates correction for a partially extended morphology.
- “BGS” indicates high-background emission has been removed.
For example, if the observation has been corrected for pointing offset and a high background the associated file name will be:
For several of the HPDPs, a further issue is addressed. There were a number of observations that tested the beam steering mirror, by using two different mirror angles within the same observation. These observations are not properly calibrated in the HSA, but were included in Hopwood et al. (2015), and are therefore provided with these HPDPs. For such observations there are two products, where one filename has the suffix “bsmTwin1” and the second “bsmTwin2”. The calibration observations which are affected and included in this set of HPDPs are:
The corresponding HPDPs’s metadata may not be complete with respect to the metadata of HIPE v14.1 reduced data found in the archive.
The file size ranges from 113 to 208 KB.
These data have been made available as they improve on the standard products available in the HSA.
Only the centre detectors of the bolometer arrays are present (SLWC3 and SSWD4).