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Pointing Offset

This includes sources which are clearly known to be a point source but the overlap of SSL and SSW still presents a discontinuity. It can be corrected using the PointingOffsetCorrectorTool available in the Herschel Interactive Processing Environment (HIPE) version 14 or above.

Header parameters:

  • Ratio SLW First Ring before background subtraction [%]: This parameter refers to the ratio of the flux of the first ring of SLW off-axis detectors to the flux of the central detector.
    This was obtained by calculating the ratios of the flux of every SLW off-axis detector to the flux of the central detector for each value of frequency. In order to eliminate the dependancy on frequency, the median was taken for each SLW off-axis detector ratio array, resulting in a single value for every one of them. The final value resulted from taking the median from these last values.
    The off-axis detectors used are SLWB2, SLWB3, SLWC2, SLWC4, SLWD2 and SLWD3.

  • Ratio SSW First Ring before background subtraction [%]: This parameter refers to the ratio of the flux of the first ring of SSW off-axis detectors to the flux of the central detector.
    This was obtained by calculating the ratios of the flux of every SSW off-axis detector to the flux of the central detector for each value of frequency. In order to eliminate the dependancy on frequency, the median was taken for each SSW off-axis detector ratio array, resulting in a single value for every one of them. The final value resulted from taking the median from these last values.
    The off-axis detectors used are SSWD3, SSWC3, SSWC4, SSWE4 and SSWE3. (SSWD5 is a dead bolometer)

  • Gap after background subtraction [Jy]: This value refers to the gap between the SLW and the SSW spectra of the central detector in the overlap region (944-1080 GHz) after the background subtraction has been done. It is the median of the difference between the flux of the SLW central detector and the flux of the SSW central detector for each frequency value.

  • Relative Gap after background subtraction [%]: This value refers to the ratio of the gap between the SLW and the SSW spectra of the central detector to the flux of the SLW central detector in the overlap region (944-1080 GHz) after the background subtraction has been done. It is calculated dividing the difference between the flux of the SLW central detector and the flux of the SSW central detector by the flux of the SLW central detector for each frequency value.


  • raDecOffset: The offset between the commanded position and the actual reconstructed pointing, which includes any systematic BSM offset (bsmOffset), but not the APE. Included in the observation's Meta Data.

Note: The Background Subtraction applied in these observations includes the emission from all off-axis detectors except for the habitual outliers SSWE2 and SSWF2. The subtracted emission was the median of the smoothed spectra from all other off-axis detectors.

File number Selection Target Obs ID Point source calibrated spectra before and after background subtraction Extended calibrated spectra Ratio SLW First Ring before background subtraction [%] Ratio SSW First Ring before background subtraction [%] Gap after background subtraction [Jy] Relative Gap after background subtraction [%] raDecOffset [arcsec] PACS Photometry Comments
2_113 Pointing Offset Iras16132maser 1342214818 ... ... 54.13 42.34 19.66 33.9 2.51 ...  
4_176 Pointing Offset MCG-03-34-064 1342249041 ... ... -22.82 -5.44 0.24 31.12 0.15 ...  
7_20 Pointing Offset AFGL 2343 1342193660 ... Not necessary for selection 0.68 2.28 1.16 21.88 9.42 ... raDecOffset value

-- Laura Susana Alvarez Mera - 2015-12-07

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Topic revision: r8 - 2017-09-13 - IvanV
 
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