Version 7.0 October 2004 Near Infrared Camera and Multi-Object Spectrometer Instrument Handbook for Cycle 14 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 any question, 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 1.0 June 1996 D.J. Axon, D. Calzetti, J.W. MacKenty, C. Skinner 2.0 July 1997 J.W. MacKenty, C. Skinner, D. Calzetti, and D.J. Axon 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. 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 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 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 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 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 Citation In publications, refer to this document as: Noll, K., et al. 2004, “NICMOS Instrument Handbook”, Version 7.0, (Baltimore: STScI). Send comments or corrections to: Space Telescope Science Institute 3700 San Martin Drive Baltimore, Maryland 21218 E-mail: [email protected] Acknowledgments The technical and operational information contained in this Handbook is the summary of the experience gained both by members of the STScI NICMOS group and by the NICMOS IDT (P.I.: Rodger Thompson, U. of Arizona) encompassing Cycle 7, Cycle 7N and Cycle 11-12. Special thanks are due to Marcia Rieke, Glenn Schneider and Dean Hines (U. of Arizona), whose help has been instrumental in many sections of this Handbook. We are also indebted to Wolfram Freudling (ST-ECF) for major contributions to the section on the NICMOS grisms. NICMOS Instrument Team Name Title Phone e-mail Keith Noll Group Lead (410) 338-1828 [email protected] Santiago Arribas Instrument Scientist (410) 338-4926 [email protected] Roelof de Jong Instrument Scientist (410) 338-4782 [email protected] Sangeeta Malhotra Instrument Scientist (410) 338 5097 [email protected] Bahram Mobasher Instrument Scientist (410) 338-4974 [email protected] Al Schultz Instrument Scientist (410) 338-5044 [email protected] Tommy Wiklind Instrument Scientist (410) 338-4396 [email protected] L. Eddie Bergeron Data Analyst (410) 338-1018 [email protected] Chun Xu Data Analyst (410 338-1265 [email protected] iii iv Acknowledgments Table of Contents Acknowledgments......................................................... iii NICMOS Instrument Team ................................................... iii Part I: Introduction ................................................................... 1 Chapter 1: Introduction and General Considerations ...................................... 3 1.1 Purpose ........................................................................... 4 1.1.1 Document Conventions .............................................. 5 1.2 Layout .............................................................................. 5 1.3 NICMOS Proposal Preparation.................................. 9 1.4 The Help Desk at STScI.............................................. 9 1.5 The NICMOS Instrument Team at STScI.............. 10 1.6 Supporting Information and the NICMOS Web Site........................................................................... 10 1.7 NICMOS History in Brief............................................ 10 1.8 Changes Relative to Cycles 7 and 7N ................... 11 1.9 Two-gyro Guiding........................................................ 13 1.10 Status of STIS............................................................ 13 1.11 Recommendations for Proposers ......................... 14 1.12 Supported and Unsupported NICMOS Capabilities ...................................................................... 16 Chapter 2: Overview of NICMOS..................... 19 2.1 Instrument Capabilities .............................................. 19 2.2 Heating, Cooling and Focus ..................................... 22 2.3 NICMOS Instrument Design..................................... 23 2.3.1 Physical Layout......................................................... 23 2.3.2 Imaging Layout ......................................................... 25 v vi Table of Contents 2.3.3 Camera NIC1............................................................ 26 2.3.4 Camera NIC2............................................................ 26 2.3.5 Camera NIC3............................................................ 26 2.3.6 Location and Orientation of Cameras ...................... 27 2.4 The NICMOS Cooling System ................................. 28 2.5 Basic Operations......................................................... 30 2.5.1 Detectors’ Characteristics and Operations ............... 30 2.5.2 Comparison to CCDs................................................ 32 2.5.3 Target Acquisition Modes ......................................... 33 2.5.4 Attached Parallels..................................................... 33 Chapter 3: Designing NICMOS Observations............................................................... 35 3.1 The APT Visual Target Tuner (VTT) ...................... 38 Part II: User’s Guide.............................................................. 39 Chapter 4: Imaging...................................................... 41 4.1 Filters and Optical Elements .................................... 41 4.1.1 Nomenclature ........................................................... 42 4.1.2 Out-of-Band Leaks in NICMOS Filters...................... 49 4.2 Photometry ................................................................... 49 4.2.1 Solar Analog Absolute Standards............................. 49 4.2.2 White Dwarf Absolute Standards.............................. 50 4.2.3 Photometric Throughput and Stability....................... 50 4.2.4 Intrapixel Sensitivity Variations................................. 51 4.2.5 Special Situations ..................................................... 51 4.3 Focus History ............................................................... 55 4.4 Image Quality ............................................................... 56 4.4.1 Strehl Ratios ............................................................. 56 4.4.2 NIC1 and NIC2 ......................................................... 57 4.4.3 NIC3.......................................................................... 61 4.4.4 PSF Structure ........................................................... 63 4.4.5 Optical Aberrations: Coma and Astigmatism............ 64 4.4.6 Field Dependence of the PSF................................... 65 4.4.7 Temporal Dependence of the PSF: HST Breathing and Cold Mask Shifts.................................... 65 4.5 Cosmic Rays ................................................................ 66 Table of Contents vii 4.6 Photon and Cosmic Ray Persistence..................... 66 4.7 The Infrared Background .......................................... 68 4.8 The “Pedestal Effect” ................................................. 74 Chapter 5: Coronagraphy, Polarimetry and Grism Spectroscopy ................................. 75 5.1 Coronagraphy .............................................................. 75 5.1.1 Coronagraphic Acquisitions...................................... 78 5.1.2 PSF Centering .......................................................... 82 5.1.3 Temporal Variations of the PSF................................ 82 5.1.4 FGS Guiding............................................................. 83 5.1.5 Cosmic Ray Persistence........................................... 84 5.1.6 Contemporary Flat Fields ......................................... 84 5.1.7 Coronagraphic Polarimetry....................................... 85 5.1.8 Coronagraphic Decision Chart.................................. 86 5.2 Polarimetry.................................................................... 88 5.2.1 NIC 1 and NIC2 Polarimetric Characteristics and Sensitivity ...................................................................... 89 5.2.2 Ghost images............................................................ 91 5.2.3 Observing Strategy Considerations.......................... 92 5.2.4 Limiting Factors ........................................................ 93 5.2.5 Polarimetry Decision Chart....................................... 94 5.3 Grism Spectroscopy ................................................... 96 5.3.1 Observing Strategy................................................... 97 5.3.2 Grism Calibration...................................................... 98 5.3.3 Relationship Between Wavelength and Pixel ........... 99 5.3.4 Sensitivity...............................................................