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April 2018 STAN

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STScI Analysis Newsletter (STAN)

Cosmic Origins Spectrograph (COS)

April 2018

In this STAN we provide an update on new reference file deliveries.



Contents




New COS/FUV TDSTAB Delivered

A new COS FUV time-dependent sensitivity (TDS) reference file (23n1744nl_tds.fits) has been delivered for use in the HST pipeline. This file accounts for the decreased slope of the TDS that has been observed since July 2015. The new reference file applies to all the COS FUV settings with the exception of G130M/1055 and 1096, for which the TDS reference file is left unchanged. Users interested in optimal absolute flux calibration should re-retrieve COS FUV data taken after July 2015 from the HST archive.

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New COS/FUV LP3 DISPTAB and LAMPTAB Delivered

A new COS FUV wavelength dispersion solution reference file (DISPTAB) and lamp template reference file (LAMPTAB) for Lifetime Position 3 (LP3), 24914346l_disp.fits and 24914347l_lamp.fits respectively, have been delivered for use in the COS calibration pipeline. The DISPTAB includes updated linear coefficients (zero points and slopes) for data taken at LP3 (i.e. between 09 Feb, 2015 and 02 Oct, 2017) with G130M standard modes (not 1055/1096/1222) and G160M. The new dispersion solutions lead to overall uncertainties in the wavelength calibration of +/- 3 pix (1 sigma). Users interested in an improved wavelength calibration for G130M and G160M data obtained at LP3 are encouraged to re-retrieve their data from the HST archive.

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New COS/FUV LP4 DISPTAB and LAMPTAB Delivered

A new COS FUV wavelength dispersion solution reference file (DISPTAB) and lamp template reference file (LAMPTAB) for Lifetime Position 4 (LP4), 24915196l_disp.fits and 24915198l_lamp.fits respectively, have been delivered for use in the COS calibration pipeline. The DISPTAB includes updated linear coefficients (zero points and slopes) for data taken at LP4 (i.e. between 02 Oct, 2017 and the present) with G130M standard modes and 1222 (not 1055/1096) and G160M. The new dispersion solutions lead to overall uncertainties in the wavelength calibration of +/- 3 pix (1 sigma). Users interested in an improved wavelength calibration for G130M and G160M data obtained at LP4 are encouraged to re-retrieve their data from the HST archive.

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New COS/FUV GSAGTAB Delivered

Two new COS FUV gain sag table reference files were delivered for use in the COS calibration pipeline. 23e1646sl_gsag.fits is used with COS blue modes and 23e16470l_gsag.fits is used with all other COS FUV observing modes. The gain sag table (GSAGTAB) tracks the locations of sagged pixels and the date that they become sagged. Users that have data taken after October 2015, particularly FUVA data at LP4, should re-retrieve their data from the HST archive to ensure that the sagged areas are handled properly by the pipeline.

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