Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 18
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Version 9.0 January 2010 Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 18 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 World Wide Web Information and other resources are available on the STIS WWW site: http://www.stsci.edu/hst/stis/ Revision History Version Date Editor 9.0 January 2010 Charles Proffitt 8.0 December 2007 Jessica Kim Quijano, Sherie Holfeltz, and Jesús Maíz-Apellániz 7.0 October 2003 Jessica Kim Quijano and Bahram Mobasher 6.0 October 2002 Charles Proffitt 5.1 July 2001 Claus Leitherer 5.0 June 2001 Claus Leitherer 4.1 July 2000 Claus Leitherer 4.0 June 2000 Claus Leitherer 3.0 June 1999 Kailash Sahu 2.0 June 1998 Nolan Walborn and Stefi Baum 1.0 June 1996 Stefi Baum Authorship This document is written and maintained by the COS/STIS Team in the Instruments Division of STScI with the assistance of associates in the Operations and Engineering Division. Contributions to the current edition were made by A. Aloisi, R. Bohlin, A. Bostroem, R. Diaz, V. Dixon, P. Goudfrooij, P. Hodge, D. Lennon, C. Long, S. Niemi, R. Osten, C. Proffitt, N. Walborn, T. Wheeler, M. Wolfe, B. York, and W. Zheng. Citation In publications, refer to this document as: Proffitt, C., et al. 2010, “STIS Instrument Handbook”, Version 9.0, (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 .................................................................. xiii Chapter 1: Introduction .......................................................1 1.1 Overview.....................................................................................1 1.2 Introduction to the Handbook................................................2 1.2.1 Document Conventions..........................................................2 1.2.2 Examples Used in this Handbook..........................................3 1.3 Handbook Layout .....................................................................4 1.4 Proposal Preparations and Observations with STIS ......................................................................................7 1.4.1 The STIS Team at STScI .......................................................8 1.5 The Help Desk at STScI..........................................................8 1.6 The STIS Web Pages and Support Information................9 1.7 Non-proprietary STIS Data ..................................................11 Chapter 2: Special Considerations for Cycle 18 ..............................................................................13 2.1 STIS Repair and Return to Operations..............................13 2.2 Summary of STIS Performance Changes Since 2004...................................................................................14 2.3 Use of Available-but-Unsupported Capabilities .............15 2.4 Should I Use COS or STIS?.................................................16 2.5 Scheduling Efficiency and Visit Orbit Limits .................19 2.6 MAMA Scheduling Policies ................................................20 2.7 Prime and Parallel Observing: MAMA Bright Object Constraints.....................................................................20 2.8 STIS Snapshot Program Policies ........................................22 iii iv Table of Contents Chapter 3: STIS Capabilities, Design, Operations, and Observations.................................23 3.1 Instrument Capabilities..........................................................23 3.2 Instrument Design...................................................................25 3.2.1 Detectors ..............................................................................25 3.2.2 STIS Physical Configuration ...............................................26 3.3 Basic Instrument Operations................................................28 3.3.1 Typical STIS Observing Sequence ......................................30 3.4 Designing STIS Observations..............................................31 3.4.1 Identify Science Requirements and Define STIS Configuration..................................................................31 3.4.2 Determine Exposure Time and Check Feasibility ...............34 3.4.3 Identify Need for Non-Science Exposures and Constraints ........................................................................35 3.4.4 Determine Total Orbit Request............................................36 Chapter 4: Spectroscopy ....................................................37 4.1 Overview...................................................................................37 4.1.1 Throughputs.........................................................................40 4.1.2 Limiting Magnitudes............................................................41 4.1.3 Saturation .............................................................................42 4.1.4 MAMA Bright Object Limits ..............................................42 4.1.5 Scanned Gratings: Prime and Secondary (Tilt) Positions .........................................................................43 4.1.6 Cross-Over Regions.............................................................44 4.2 First-Order Long-Slit Spectroscopy...................................45 4.2.1 Gratings for First-Order Spectroscopy ................................45 4.2.2 Slits for First-Order Spectroscopy .......................................46 4.2.3 STIS Pseudo-Aperture Positions .........................................48 4.2.4 Detailed First-Order Spectroscopic Information .................52 4.3 Echelle Spectroscopy in the Ultraviolet............................52 4.3.1 Echelle Gratings...................................................................53 4.3.2 Slits for Echelle Spectroscopy .............................................54 4.3.3 Detailed Echelle Information...............................................54 4.4 Objective Prism Spectroscopy.............................................55 Table of Contents v Chapter 5: Imaging.................................................................59 5.1 Imaging Overview ..................................................................59 5.1.1 Caveats for STIS Imaging....................................................61 5.1.2 Throughputs and Limiting Magnitudes ...............................62 5.1.3 Signal-To-Noise Ratios........................................................64 5.1.4 Saturation .............................................................................65 5.2 Optical CCD Imaging ............................................................65 5.2.1 Unfiltered (Clear) CCD Imaging: 50CCD & 50CORON....67 5.2.2 Optical Longpass: F28X50LP .............................................67 5.2.3 [O III]: F28X50OIII.............................................................67 5.2.4 [O II]: F28X50OII ...............................................................68 5.3 Ultraviolet Imaging with the MAMA Detectors.............69 5.3.1 Bright Object Limits ............................................................70 5.3.2 Optical Performance ............................................................70 5.3.3 Unfiltered (Clear) MAMA Imaging: 25MAMA .................71 5.3.4 FUV Red Leak .....................................................................71 5.3.5 Longpass-Filtered MAMA Imaging: F25SRF2 and F25QTZ ............................................................74 5.3.6 MAMA Narrow-Band-Filtered Imaging .............................75 5.4 Neutral Density Filters...........................................................78 Chapter 6: Exposure Time Calculations .............81 6.1 Overview...................................................................................81 6.1.1 The STIS Exposure Time Calculators .................................81 6.2 Determining Count Rates from Sensitivities ...................82 6.2.1 Spectroscopy........................................................................83 6.2.2 Imaging ................................................................................86 6.3 Throughput and Sensitivity ..................................................88 6.4 Computing Exposure Times.................................................89 6.4.1 Calculating Exposure Times for a Given Signal-to-Noise .............................................................89 6.5 Detector and Sky Backgrounds ...........................................91 6.5.1 Detector Backgrounds..........................................................91 6.5.2 Sky Background...................................................................91 6.6 Tabular Sky Backgrounds.....................................................97 6.7 Extinction Correction...........................................................100 6.8 Exposure Time Examples ...................................................101 6.8.1 Spectroscopy of Diffuse Source (M86) .............................101 vi Table of Contents 6.8.2 Spectroscopy of Solar-Analog Star P041-C ......................102 6.8.3 Extended Source with Flux in cgs Units (NGC 6543): Imaging and Spectroscopy.....................................................104