Version 10.0 December 2007 Near Infrared Camera and Multi-Object Spectrometer Instrument Handbook for Cycle 17 Space Telescope Science Institute 3700 San Martin Drive Baltimore, Maryland 21218 [email protected] Operated by the Association of Universities for Research in Astronomy, Inc., for the National Aeronautics and Space Administration User Support For prompt answers to questions, please contact the STScI Help Desk. • E-mail: [email protected] • Phone: (410) 338-1082 (800) 544-8125 (U.S., toll free) World Wide Web Information and other resources are available on the NICMOS World Wide Web site: • URL: http://www.stsci.edu/hst/nicmos Revision History Version Date Editors 10.0 December 2007 E. Barker, T. Dahlen, A. Koekemoer, L. Bergeron, R. de Jong, H. McLaugh- lin, N. Pirzkal, B. Shaw, T. Wiklind 9.0 October 2006 E. Barker, N. Pirzkal, K. Noll, S. Arribas, L. Bergeron, R. de Jong, A. Koekemoer, H. McLaughlin, T. Wiklind, C. Xu 8.0 October 2005 A. Schultz, K. Noll, E. Barker, S. Arribas, L. Bergeron, R. de Jong, S. Mal- hotra, B. Mobasher, T. Wiklind, C. Xu 7.0 October 2004 K. Noll, A. Schultz, E. Roye, S. Arribas, L. Bergeron, R. de Jong, S. Malhotra, B. Mobasher, T. Wiklind, C. Xu 6.0 October 2003 E. Roye, K. Noll, S. Malhotra, D. Calzetti, S. Arribas, L. Bergeron, T. Böker, M. Dickinson, B. Mobasher, L. Petro, A. Schultz, M. Sosey, C. Xu 5.0 October 2002 S. Malhotra, L. Mazzuca, D. Calzetti, S. Arribas, L. Bergeron, T. Böker, M. Dickinson, B. Mobasher, K. Noll, L. Petro, E. Roye, A. Schultz, M. Sosey, C. Xu 4.1 May 2001 A. Schultz, S. Arribas, L. Bergeron, T. Böker, D. Calzetti, M. Dickinson, S. Holfeltz, B. Monroe, K. Noll, L. Petro, M. Sosey 4.0 May 2000 T. Böker, L. Bergeron, D. Calzetti, M. Dickinson, S. Holfeltz, B. Monroe, B. Rauscher, M. Regan, A. Sivaramakrishnan, A. Schultz, M. Sosey, A. Storrs 3.0 June 1999 D. Calzetti, L. Bergeron, T. Böker, M. Dickinson, S. Holfeltz, L. Mazzuca, B. Monroe, A. Nota, A. Sivaramakrishnan, A. Schultz, M. Sosey, A. Storrs, A. Suchkov. 2.0 July 1997 J.W. MacKenty, C. Skinner, D. Calzetti, and D.J. Axon 1.0 June 1996 D.J. Axon, D. Calzetti, J.W. MacKenty, C. Skinner Citation In publications, refer to this document as: Barker, E., Dahlen, T., et al. 2007, “NICMOS Instrument Handbook”, Version 10.0, (Baltimore: STScI). Send comments or corrections to: Space Telescope Science Institute 3700 San Martin Drive Baltimore, Maryland 21218 E-mail: [email protected] Table of Contents Acknowledgments.........................................................ix Chapter 1: Introduction and General Considerations ...................................... 1 1.1 Purpose ........................................................................... 2 Document Conventions ........................................................ 3 1.2 Layout .............................................................................. 3 1.3 NICMOS Proposal Preparation.................................. 6 1.4 The Help Desk at STScI.............................................. 6 1.5 The NICMOS Instrument Team at STScI................ 7 1.6 Supporting Information and the NICMOS Web Site............................................................................. 7 1.7 NICMOS History in Brief.............................................. 7 1.8 Three-Gyro Guiding...................................................... 8 1.9 Recommendations for Proposers.............................. 9 1.10 Supported and Unsupported NICMOS Capabilities ...................................................................... 12 Chapter 2: Overview of NICMOS..................... 15 2.1 Instrument Capabilities .............................................. 15 2.2 Heating, Cooling and Focus ..................................... 17 2.3 NICMOS Instrument Design..................................... 19 2.3.1 Physical Layout ........................................................ 19 2.3.2 Imaging Layout ......................................................... 21 2.3.3 Camera NIC1............................................................ 22 2.3.4 Camera NIC2............................................................ 22 2.3.5 Camera NIC3............................................................ 22 2.3.6 Location and Orientation of Cameras ...................... 23 iii iv Table of Contents 2.4 Basic Operations......................................................... 24 2.4.1 Detectors’ Characteristics and Operations ............... 24 2.4.2 Comparison to CCDs................................................ 25 2.4.3 Target Acquisition Modes ......................................... 26 2.4.4 Attached Parallels..................................................... 27 Chapter 3: Designing NICMOS Observations............................................................... 29 3.1 Overview of Design Process .................................... 29 3.2 APT and Aladin............................................................ 32 Chapter 4: Imaging...................................................... 33 4.1 Filters and Optical Elements .................................... 33 4.1.1 Nomenclature ........................................................... 33 4.1.2 Out-of-Band Leaks in NICMOS Filters...................... 34 4.2 Photometry ................................................................... 41 4.2.1 Solar Analog Absolute Standards............................. 41 4.2.2 White Dwarf Absolute Standards.............................. 42 4.2.3 Photometric Throughput and Stability ...................... 42 4.2.4 Count Rate Dependent Non-linearity........................ 43 4.2.5 Intrapixel Sensitivity Variations................................. 44 4.2.6 Special Situations ..................................................... 45 4.3 Focus History ............................................................... 48 4.4 Image Quality ............................................................... 50 4.4.1 Strehl Ratios ............................................................. 50 4.4.2 NIC1 and NIC2 ......................................................... 50 4.4.3 NIC3.......................................................................... 54 4.4.4 PSF Structure ........................................................... 56 4.4.5 Optical Aberrations: Coma and Astigmatism............ 57 4.4.6 Field Dependence of the PSF .................................. 58 4.4.7 Temporal Dependence of the PSF: HST Breathing and Cold Mask Shifts............................ 58 4.5 Cosmic Rays ................................................................ 59 4.6 Photon and Cosmic Ray Persistence..................... 60 4.7 The Infrared Background .......................................... 62 4.8 The “Pedestal Effect” ................................................. 66 Table of Contents v Chapter 5: Coronagraphy, Polarimetry and Grism Spectroscopy ................................. 69 5.1 Coronagraphy .............................................................. 69 5.1.1 Coronagraphic Acquisitions...................................... 72 5.1.2 PSF Centering .......................................................... 76 5.1.3 Temporal Variations of the PSF ............................... 76 5.1.4 FGS Guiding............................................................. 77 5.1.5 Cosmic Ray Persistence........................................... 78 5.1.6 Contemporary Flat Fields ......................................... 78 5.1.7 Coronagraphic Polarimetry....................................... 79 5.1.8 Coronagraphic Decision Chart ................................. 79 5.2 Polarimetry.................................................................... 81 5.2.1 NIC 1 and NIC2 Polarimetric Characteristics and Sensitivity ............................................................... 81 5.2.2 Ghost images............................................................ 84 5.2.3 Observing Strategy Considerations.......................... 85 5.2.4 Limiting Factors ........................................................ 86 5.2.5 Polarimetry Decision Chart....................................... 87 5.3 Grism Spectroscopy ................................................... 89 5.3.1 Observing Strategy................................................... 90 5.3.2 Grism Calibration...................................................... 92 5.3.3 Relationship Between Wavelength and Pixel ........... 92 5.3.4 Sensitivity.................................................................. 93 5.3.5 Intrapixel Sensitivity.................................................. 96 5.3.6 Grism Decision Chart................................................ 96 Chapter 6: NICMOS Apertures and Orientation ......................................................... 99 6.1 NICMOS Aperture Definitions .................................. 99 6.2 NICMOS Coordinate System Conventions......... 100 6.3 Orients ......................................................................... 101 Chapter 7: NICMOS Detectors ........................ 103 7.1 Detector basics .......................................................... 103 vi Table of Contents 7.2 Detector Characteristics .......................................... 105 7.2.1 Overview................................................................. 105 7.2.2 Dark Current ........................................................... 106 7.2.3 Flat Fields and the DQE ......................................... 108 7.2.4 Read Noise............................................................. 111