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A Beginner’s Guide to Using IRAF IRAF Version 2.10 Jeannette Barnes Central Com

A Beginner’s Guide to Using IRAF IRAF Version 2.10 Jeannette Barnes Central Computer Services National Optical Astronomy Observatories†† Tucson, Arizona 85726 August 1993 ABSTRACT IRAF is a general Image Reduction and Analysis Facility providing a wide range of image processing tools for the user. IRAF is a product of the National Optical Astronomy Observatories and was developed for the astronomical com- munity although researchers in other scientiﬁc ﬁelds have found IRAF to be useful for general image processing. This document is intended to provide the novice user with a brief introduction to IRAF and its Command Language (CL) user interface. The author would like to thank the members of the IRAF group for com- ments and suggestions during the preparation of this document. DRAFT 3333333333333333 ††Operated by the Association of Universities for Research in Astronomy, Inc. under cooperative agreement with the National Science Foundation. CONTENTS 1. Introduction....................................................................................................................... 1 1.1. Overview.................................................................................................................... 1 1.2. Getting IRAF............................................................................................................ 2 1.3. Documentation ......................................................................................................... 2 1.4. IRAF support services ........................................................................................... 2 1.5. Style conventions .................................................................................................... 2 2. Getting started................................................................................................................. 3 2.1. Host startup ﬁles...................................................................................................... 3 2.2. IRAF startup ﬁles.................................................................................................... 3 2.3. Logging in/out of IRAF........................................................................................ 7 3. The basics............................................................................................................................ 7 3.1. Setting up your IRAF environment................................................................... 7 3.1.1. Deﬁning your terminal type ........................................................................ 8 3.1.2. Selecting hard copy devices ........................................................................ 8 3.1.3. Choosing an editor....................................................................................... 8 3.2. Packages and tasks.................................................................................................. 9 3.3. General help facilities............................................................................................ 9 3.3.1. Simple tools ................................................................................................. 9 3.3.2. Online manual pages ................................................................................... 10 3.3.3. The HELP task............................................................................................. 10 3.3.4. The PHELP task .......................................................................................... 10 3.3.5. Printing online manual pages ...................................................................... 11 3.3.6. Finding a task with a particular function (REFERENCES) ....................... 11 3.4. Doing things with directories.............................................................................. 11 3.4.1. Creating/removing directories ..................................................................... 11 3.4.2. Changing directories.................................................................................... 12 3.5. Parameter ﬁles.......................................................................................................... 12 3.5.1. Listing parameters........................................................................................ 13 3.5.2. Editing parameters....................................................................................... 13 3.5.3. Resetting task parameters............................................................................ 14 3.6. Executing tasks ........................................................................................................ 14 3.6.1. General syntax ............................................................................................. 14 3.6.2. Running tasks in the background................................................................ 15 3.6.3. Aborting tasks.............................................................................................. 16 3.7. Data ﬁles .................................................................................................................... 16 3.8. IRAF image ﬁles ..................................................................................................... 17 3.8.1. The IRAF image header .............................................................................. 18 3.8.2. The IRAF pixel ﬁle...................................................................................... 18 3.8.3. Pixel data types............................................................................................ 19 3.8.4. Image dimensions ........................................................................................ 20 3.8.5. General image tools..................................................................................... 20 4. Reading and writing data ....................................................................................... 21 4.1. General tape handling facilities.......................................................................... 21 4.2. Setting tape densities ............................................................................................. 22 4.3. FITS facilities........................................................................................................... 22 4.3.1. Reading FITS images .................................................................................. 22 4.3.2. Writing FITS images ................................................................................... 24 4.4. Text ﬁles..................................................................................................................... 25 4.5. Non-standard data formats ................................................................................... 26 4.6. Tar ﬁle format .......................................................................................................... 26 4.7. Miscellaneous I/O tasks ........................................................................................ 26 5. Plotting data...................................................................................................................... 27 5.1. Interactive graphics cursor mode....................................................................... 27 5.2. One-dimensional (vector) plotting tasks.......................................................... 29 5.3. Two-dimensional plotting tasks ......................................................................... 29 5.4. Tasks that manipulate graphics metacode ﬁles ............................................. 30 6. Using the image display............................................................................................ 30 6.1. Displaying IRAF images ...................................................................................... 31 6.2. Using the interactive image cursor.................................................................... 32 6.2.1. Reading the image cursor position.............................................................. 32 6.2.2. Examining and editing images .................................................................... 33 7. Coordinate systems within IRAF...................................................................... 33 8. Additional interesting topics................................................................................. 35 8.1. Input/output redirection......................................................................................... 35 8.2. Image sections.......................................................................................................... 36 8.3. File and image name templates .......................................................................... 36 8.4. The @ﬁle ................................................................................................................... 37 8.5. History and command logging............................................................................ 37 8.6. Using the CL as a calculator ............................................................................... 38 8.7. IRAF networking..................................................................................................... 38 8.7.1. Syntax .......................................................................................................... 39 8.7.2. The .irafhosts ﬁle......................................................................................... 39 9. Writing your own software.................................................................................... 39 9.1. Writing IRAF scripts ............................................................................................. 40 9.2. The IMFORT interface.......................................................................................... 40 9.3. Programming in IRAF with SPP ....................................................................... 40 Appendix A The IRAF Packages...................................................................................... 41 Appendix B The NOAO Packages ................................................................................... 47 Appendix C IRAF Image Formats ................................................................................... 60 Appendix D Fixing Pixel File Pathnames...................................................................... 61 Appendix E The IRAF Network Archive ...................................................................... 62 Appendix F IRAF Layered Packages .............................................................................. 63 Appendix G A Selected List of IRAF Documentation.............................................. 64 A Beginner’s Guide to Using IRAF IRAF Version 2.10 Jeannette Barnes Central Computer Services National Optical Astronomy Observatories†† Tucson, Arizona 85726 August 1993 1. Introduction 1.1. Overview IRAF is a general Image Reduction and Analysis Facility providing a wide range of image processing tools for the user. IRAF is a product of the National Optical Astronomy Observa- tories (NOAO) and was developed for the astronomical community although researchers in other scientiﬁc ﬁelds have found IRAF to be useful for general image processing. This docu- ment is intended to provide the novice user with a brief introduction to IRAF and its Command Language (CL) user interface. Only the IRAF "core" system will be discussed in this document. The NOAO science software (general spectroscopic and photometric reduction and analysis tools) is included in all IRAF tributions, but a discussion of this software is better covered elsewhere. The IRAF core system provides the user with a wide selection of image processing tools using a command line interface. Commands, called tasks, are executed to perform various func- tions; each task has a parameter ﬁle that the user can modify to affect the output of the task. Highlights of the system include: d similar environment regardless of host system d query and command line interface d pipes and redirection d background job queue d extensive online help d interactive graphics and image display d text and graphics hardcopy d tape I/O d FITS image I/O d several user programming environments d world coordinate systems Additional IRAF software packages, called layered packages, are available from a variety of sources and can be installed to run under the IRAF environment. See Appendix F for more information. 3333333333333333 ††Operated by the Association of Universities for Research in Astronomy, Inc. under cooperative agreement with the National Science Foundation. - 2 - 1.2. Getting IRAF IRAF is distributed by NOAO and is available over the Internet free of charge to any interested party. Taped distributions are available for a small handling fee. The IRAF system runs on a wide selection of UNIX-based and VMS platforms. See Appendix E for details about acquiring the IRAF distribution. 1.3. Documentation A large selection of IRAF documentation is available. A selected list of documents is pro- vided in Appendix G. All IRAF documentation (excluding the online help/manual pages, see §3.3.2.), is available in the IRAF network archive in the iraf/docs directory. A README cross-reference ﬁle lists the documents and their ﬁle names as they appear in the archive. These ﬁles are in either compressed PostScript or compressed ASCII format. See Appendix E for more information about the network archive. Printed copies of these documents are available upon request. An IRAF Newsletter is published periodically, and it is a valuable source of information for even the casual IRAF user. Old newsletters are available in the IRAF network archive. Anyone can receive the Newsletter; simply send your name, address, and email address to iraf@noao.edu and request this service. The IRAF Newsletter is distributed by posted mail; an electronic news service will be implemented shortly as well. 1.4. IRAF support services General questions concerning IRAF can be directed to iraf@noao.edu or 5355::IRAF. For those of you wishing to talk to someone directly the IRAF Hotline number is (602)-325-4160. Posted inquiries should be sent to Jeannette Barnes, NOAO, P.O. Box 26732, Tucson, AZ 85726 USA. 1.5. Style conventions The following conventions are used throughout this document. d IRAF tasks and package names are in CAPITAL LETTERS in the running text of this document. Since IRAF is case sensitive the user should be aware that the capital letters are being used only as a visual aid to the reader. d Terminal output is in typewriter font. d Input parameters that require local values to be substituted in their place in order for the example to execute properly are in <typewriter> font but enclosed in "angle brack- ets", as shown. d Text that you type in exactly as shown is in typewriter bold font. d References, directories and ﬁle names, parameters and parameter values, and other impor- tant words and phrases are in italics. d The cl> prompt is used in most IRAF examples. The prompt the user actually sees on the terminal will depend on the last IRAF package loaded. d An image of the galaxy M51 is included with all IRAF distributions and is often used in the examples in this document. The image is called dev$pix; the same image but with a different header ﬁle is also used in some examples and is known as dev$wpix. d The examples in this document assume that the needed packages have been loaded at IRAF startup time, as deﬁned by the distributed IRAF system (see §3.2.). d For the sake of brevity, the pronoun "he" is used in a generic sense, to include all users, be they female or male. - 3 - 2. Getting started 2.1. Host startup ﬁles The host level ﬁles necessary to run IRAF will vary depending on the host machine and window environment in which you plan to execute IRAF. A workstation environment (Sun- View, OpenWindows, DECwindows, X Windows) will require additional host level ﬁles than those used by the conventional graphics terminal environment. A discussion of the host level ﬁles used in the workstation environment uploads/s1/ iraf-guide.pdf