+----------------------------------------------------------+ | NICMOS | STScI Analysis Newsletter | 16 May 2007 +----------------------------------------------------------+ Visit the NICMOS web site http://www.stsci.edu/hst/nicmos "New in the Last 45 Days" for all new information about NICMOS. CONTENTS: -NICMOS Data Handbook Version 7.0 Release -A new Instrument Science Report regarding the new SAAclean PyRAF Task Instrument Science Report -Extended NICMOS Calibration Plans +----------------------------------------------------------+ NICMOS Data Handbook Version 7.0 Release The latest version of the NICMOS Data Handbook has been released forgeneral distribution. It can be found on the NICMOS web site at http://www.stsci.edu/hst/nicmos/documents/handbooks/DataHandbookv7. The changes include updates to the ESA NICMOSlook and aXe development and their use. Significant updates have been made to the SAAclean and StayPuft explanations and implementations. The new Count-Rate Non-linearity section introduces a new STSDAS task rnlincor, which we expect to be delivered in the next STSDAS release. Minor updates have been made to the NICMOS Dark Current and Bias, Dark Current, Amplifier Glow, Bias, Shading, and "Pedestal", Random Uncertainties (i.e., noise) in the Temperature- Dependent Darks, and Systematic Uncertainties in the Temperature- Dependent Darks. +----------------------------------------------------------+ NICMOS ISR 2007-001: Removing Post-SAA Persistence in NICMOS Data http://www.stsci.edu/hst/nicmos/documents/isrs/isr_2007_001.pdf A general concern with NICMOS images is the issue of persistence, or residual charge from bright sources and cosmic rays that remains trapped in pixels and is gradually released during subsequent exposures. This is particularly noticeable after HST transits of the South Atlantic Anomaly (SAA), where the cosmic ray rate is so high that their residual flux contributes a significant noise component to many subsequent exposures. We describe the SAAclean task which can be run on post-SAA NICMOS images to identify the amount of charge in each pixel that can be attributed to persistent flux from SAA cosmic rays, and apply a correction based on an SAA persistence model to remove this flux from the data. This task has so far been tested on a variety of NICMOS data, and this represents the most recent update of this task in the PyRAF/STSDAS environment to the HST observer community. The NICMOS team would welcome feedback from the community on the use of this task or any suggestions for ! ! ! inclusion in future releases. +----------------------------------------------------------+ Extended NICMOS Calibration Plans The NICMOS Cycle 15 calibration plans are being extended up to the upcoming servicing mission in 2008 (SM4). It is planned that several monitoring calibration proposals from the Baseline Cycle 15 calibration plans, which are currently underway, will simply be extended as-is. Such programs are the dark stability, the flat- field stability, the photometric stability, and the focus stability programs. The Cycle 15 non-linearity program will also be extended in order to cover a longer time baseline. Additional observations of infrared spectrophotometric standards will be undertaken using both imaging and grism observations. This will both improve the accuracy of the infrared flux measurements of these objects as well as detect any light variability in these objects. We are also planning for the addition of several new calibration programs: A grism calibration program will aim at determining the dispersion solution of the NICMOS grism modes in different positions on the detectors. M! ! ! oreover, we are aiming at using available pure parallels, periods when another instrument is the prime HST instrument, to obtain an extensive set of MULTIACCUM dark observations using all the modes used during past GO proposals. Parallel observations will also be used to obtain additional flat-field observations, thereby ignificantly increasing the pool of available flat-fields for NICMOS over a larger period of time. These plans are currently being finalized; we would welcome input from the community on any specific aspects of NICMOS operation that could be addressed in this extended calibration plan. +----------------------------------------------------------+ For more detailed information and updates, please consult the NICMOS webpages: http://www.stsci.edu/hst/nicmos +----------------------------------------------------------+ | Help: help@stsci.edu +----------------------------------------------------------+ | To subscribe or unsubscribe to the STAN, send a message | to majordomo@stsci.edu with the subject line blank and | the following in the body: [un]subscribe nicmos_news +----------------------------------------------------------+ | The Space Telescope Science Institute is operated by the | Association of Universities for Research in Astronomy, | Inc., under NASA contract NAS5-26555. +----------------------------------------------------------+
