New Mars Exploration Rover Panoramic Camera (Pancam) Version 2 Radiance- Calibrated RDRs. Jim Bell (ASU), Jonathan Joseph (Cornell) 29 July, 2016 This is a brief summary of how new Version 2 radiance-calibrated ("RAD") RDRs for the Mars Exploration Rover Pancam investigation (Bell et al., 2003) have been updated relative to the existing Version 1 radiance-calibrated RDRs previously archived in the PDS. Specifically, these modified processing steps were applied to the original Pancam EDRs, compared to the steps used to create the original Version 1 radiance-calibrated RDRs (documented in Bell et al., 2006): A) "Besting" of the existing PDS-archived raw Pancam EDRs: A number of factors, such as the late reconstruction of previously-missing data packets or the availability of updated pointing information, led to inconsistencies between the PDS-archived raw Pancam EDRs and the currently "best" available tactical EDRs. Thus, we checked the PDS released EDRs for completeness against the current tactical EDRs and fixed any missing or incorrect data using corresponding image thumbnails, adjacent images, or known/derivable values. This besting process was completed for all data from MER-A (Spirit), and for data from sols 1-4000 from MER-B (Opportunity). B) Application of a new Pancam CCD bias level model using in-flight data. We have improved the model of the Pancam CCD bias (background) level, using a detailed analysis of in-flight bias data downlinked during the mission. Specifically, tens of thousands of reference pixel images downlinked over the course of the mission have now been included in the assessment of background signal levels. Roughly 50% of reference pixel images have been excluded from the model due to small random fluctuations in bias from bottom to top of the CCD, significantly smoothing out some of the noise in the original, "averaged" bias model for the CCDs. While reference pixel images with anomalous fluctuations are used to calibrate their corresponding images, the bias model used for images without corresponding reference pixel images ignores such fluctuations, which we were unable to model. We believe that these fluctuations could be caused by minor electronic interference from other rover systems during image acquisition. C) Application of a new time-dependent Pancam CCD dark current model using in- flight data. We have developed and implement a more robust method for modeling and removing the Pancam CCD dark current signal (thermally-induced charge that builds up over time during integrations and readout) over time, based on a detailed analysis of the time history of dark current measurements taken throughout the mission. We have improved the modeling of CCD pixels whose dark current signal has changed over time, and extended the model to include all dark current observations acquired. D) Application of a new set of time-dependent Pancam CCD flatfields using in- flight data. The flatfields used to correct MER Pancam images correct for both the responsivity of the individual pixels on the CCD as well as the light attenuation across the CCD caused by the filters and optics. The responsivity of Pancam pixels relative to their immediate neighbors has remained remarkably consistent over time. However, the light attenuation across the CCD has changed significantly over time, particularly on MER-B due to the accumulation and occasional removal of dust on the outer sapphire window. While the effects of dust on the sapphire window are lighting-geometry dependent, we have found that we can improve the image quality significantly by correcting for these variations by using flatfields generated from occasional images of uniform regions of the Martian sky taken as close in time as possible after the observed changes. A larger set of these "sky flat" images has been used to correct for flatfield variations in the Pancam data. In addition to these changes noted above, the Version 2 Pancam RAD RDRs also contain a correction to an error in the ELEVATION keyword stored in the PDS file labels, which indicates the pointing of the camera field of view in the azimuth/elevation coordinate frame. Specifically, the originally-archived Version 1 RDRs incorrectly listed elevation values as 0 deg for level horizon viewing, and increasing positive downward. The new Version 2 RDRs flip that convention and indicate elevation values as increasing when the cameras are pointed upward, and decreasing when the cameras are pointed downward. New Version 2 Pancam calibrated radiance ("RAD") RDR files were created using these updated bias, dark current, and flatfield corrections applied to the bested set of EDRs, and with the ELEVATION correction made in their file labels. New Version 2 RAD files have been created for all MER-A (Spirit) Pancam RDRs, and for MER-B (Opportunity) Pancam RDRs through sol 4000. References cited: Bell III, J.F., J. Joseph, J.N. Sohl-Dickstein, H.M. Arneson, M.J. Johnson, M.T. Lemmon, and D. Savransky, In-flight calibration and performance of the Mars Exploration Rover Panoramic Camera (Pancam) Instruments, J. Geophys. Res., 111, E02S03, doi:10.1029/2005JE002444, 2006. Bell III, J.F., S.W. Squyres, K.E. Herkenhoff, J.N. Maki, H.M. Arneson, D. Brown, S.A. Collins, A. Dingizian, S.T. Elliot, E.C. Hagerott, A.G. Hayes, M.J. Johnson, J.R. Johnson, J. Joseph, K. Kinch, M.T. Lemmon, R.V. Morris, L Scherr, M. Schwochert, M.K. Shepard, G.H. Smith, J.N. Sohl-Dickstein, R. Sullivan, W.T. Sullivan, and M. Wadsworth, The Mars Exploration Rover Athena Panoramic Camera (Pancam) Investigation, J. Geophys. Res., 108 (E12), doi:10.1029/2003JE002070, 2003.