Advancements in Long Wavelength Channel Calibration Procedures and Results

1. LWC CALIBRATION Calibration History, Computation and Validity of provided Calibration Curves • The Long Wavelength Channel calibration procedure is currently on its version 4 • It is the result of an extensive study of the thermal/statistical behavior of PFS • This procedure has been extensively validated and is currently providing good results (H2O, temperature vertical profiles, ice/dust/clouds studies, surface temperature maps) • Providedcurves can be usedat thermal regime condition (> 90% of data) • Interpolationisrequired for non-regime conditions • Residual issues may occur (tilts and wiggles, phase). See Giuranna this afternoon. MEx and VExDATA WORKSHOP - PFS and SOIR experiments - 27 June - 1st July 2011, ESA/ESAC,Spain

2. CALIBRATION HISTORY (1/2) LWC calibrations V1 had some Zero-Level problems These problems have been solved with Calibration procedure V2 MEx and VExDATA WORKSHOP - PFS and SOIR experiments - 27 June - 1st July 2011, ESA/ESAC,Spain

3. Orbit 100 average of 200 spectra Fixed with Calib_v4 CALIBRATION HISTORY (2/2) • Minor differences between V2 and V3 (better spectral calibration; new geometries) • Instrumental artifacts still present in V3, expecially above 800 cm-1 MEx and VExDATA WORKSHOP - PFS and SOIR experiments - 27 June - 1st July 2011, ESA/ESAC,Spain

4. FWD REV This study also shows some other interesting results: • The mechanical vibrations affect also the LW channel spectra; • they cause systematic statistical errors in the measured signal of the same order of magnitude of the variations due to the detector temperature changes. • In other words, even at thermal regime conditions ( TD~287.0 K), a stable source (i.e. DS) shows variations of ~ 5-7% of the signal; THERMAL /STATISTICAL ANALYSIS • An extensive study of the thermal behavior of the instrument has been done (2006) • A set of 5360 averages of “Deep Space” and “Internal Black-Body” measurements has been collected, monitoring TD, TBB and TIB. The main "expected" results are: • As already found in laboratory, the instrumental thermal emission is mainly controlled by the detector temperature; • Interesting enough, this systematic statistical errors have a ZERO-AVERAGE VALUE: • averaging independent sets of Deep-Space spectra (at a given detector temperature) we get identical averages. • as a consequence of point 1), the measured signal depends on the detector temperature; • This dependence on the detector temperature is linear and, knowing the detector temperature, we have the instrumental thermal emission by interpolation; MEx and VExDATA WORKSHOP - PFS and SOIR experiments - 27 June - 1st July 2011, ESA/ESAC,Spain

5. CALIB_V4 From the previous analysis follows that: • More than 90% of the Martian data and 99% of the Deep-Space measurements are acquired with the detector temperature well stable at ~287.0 K; consequently, thanks to point c), averaging all the DS measurements we have a very accurate estimate of the thermal emission of the instrument at thermal regime condition (i.e. for than 90% of the data) -> better radiometric calibration; • Thanks to point 3), we have a very accurate estimate of the thermal emission of the instrument also for non-regime conditions -> better radiometric calibration; • we don't need to use the calibration measurements within each session to have the instrumental thermal emission and responsivity. ALL orbits can now be calibrated! • The residuals (artifacts, slopes etc...) sometimes present in the LWC spectra, will be reduced but will STILL be present, since they are NOT ONLY due to changes in the thermal conditions of the instrument, but also to the external mechanical vibrations and the two effects are of the same order of magnitude. MEx and VExDATA WORKSHOP - PFS and SOIR experiments - 27 June - 1st July 2011, ESA/ESAC,Spain