From owner-fitsbits Wed Aug 6 17:18:44 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id RAA16102 for fitsbits-spinner; Wed, 6 Aug 1997 17:18:44 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id RAA16099 for ; Wed, 6 Aug 1997 17:18:41 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id RAA13401 for fitsbits at majordomo.cv.nrao.edu; Wed, 6 Aug 1997 17:18:40 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id LAA08654 for ; Tue, 5 Aug 1997 11:37:11 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id LAA11828 for ; Tue, 5 Aug 1997 11:37:10 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id LAA27705; Tue, 5 Aug 1997 11:37:09 -0400 To: fitsbits at fits.cv.nrao.edu Date: Tue, 05 Aug 1997 11:24:04 -0400 From: "William T.(Tom) Bridgman" Message-ID: <33E74594.2455 at grossc.gsfc.nasa.gov> Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!europa.clark.net!4.1.16.34!cpk-news-hub1.bbnplanet.com!news.bbnplanet.com!news.new-york.net!news.columbia.edu!osiris.giss.nasa.gov!newsfeed.gsfc.nasa.gov!usenet Reply-To: bridgman at grossc.gsfc.nasa.gov Subject: FITS keywords and the year 2000 problem Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk We've been examining a number of our FITS file generators and are concerned about possible Y2K problems in our archived FITS files. The NOST standard seems to restrict the DATE and DATE-OBS keywords to dd/mm/yy format for generating human-readable dates. We often utilize other date formats (yyyy.ddd and TJD) with mission-defined keywords which avoid this problem but we are still concerned. Naturally, we could also define additional keywords to produce alternative human-readable dates in dd/mm/yyyy format but we're wondering if there are plans to appropriately update the standards. Thanks, Tom -- Tom Bridgman bridgman at grossc.gsfc.nasa.gov NASA Goddard Space Flight Center 301-286-1346 Code 660.1 Greenbelt, MD 20771 From owner-fitsbits Wed Aug 6 17:19:32 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id RAA16115 for fitsbits-spinner; Wed, 6 Aug 1997 17:19:32 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id RAA16110 for ; Wed, 6 Aug 1997 17:19:28 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id RAA13406 for fitsbits at majordomo.cv.nrao.edu; Wed, 6 Aug 1997 17:19:27 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id NAA09148 for ; Tue, 5 Aug 1997 13:38:51 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id NAA11918 for ; Tue, 5 Aug 1997 13:38:50 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id NAA00155; Tue, 5 Aug 1997 13:38:49 -0400 To: fitsbits at fits.cv.nrao.edu Date: 5 Aug 1997 13:11 EDT From: bschlesinger at nssdca.gsfc.nasa.gov (Barry M. Schlesinger) Message-ID: <5AUG199713112883 at nssdca.gsfc.nasa.gov> Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!news.maxwell.syr.edu!news-feed.inet.tele.dk!novia!nick.arc.nasa.gov!newsfeed.gsfc.nasa.gov!nssdca.gsfc.nasa.gov!bschlesinger References: <33E74594.2455 at grossc.gsfc.nasa.gov> Subject: Re: FITS keywords and the year 2000 problem Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk In article <33E74594.2455 at grossc.gsfc.nasa.gov>, bridgman at grossc.gsfc.nasa.gov writes... >We've been examining a number of our FITS file generators and are >concerned about possible Y2K problems in our archived FITS files. > >The NOST standard seems to restrict the DATE and DATE-OBS keywords to >dd/mm/yy format for generating human-readable dates ... we're >wondering if there are plans to appropriately update the standards. > There is currently a proposal under consideration by the IAU FITS Working Group that provides a new date format with a four-digit year. The text is available at ftp://nssdc.gsfc.nasa.gov/pub/fits/year2000_proposal.txt. Barry Schlesinger FITS Support Office GSFC/ADF From owner-fitsbits Thu Aug 7 12:09:38 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id MAA20520 for fitsbits-spinner; Thu, 7 Aug 1997 12:09:38 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id MAA20517 for ; Thu, 7 Aug 1997 12:09:35 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id MAA14600 for fitsbits at majordomo.cv.nrao.edu; Thu, 7 Aug 1997 12:09:34 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id MAA20497; Thu, 7 Aug 1997 12:08:17 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id MAA14577; Thu, 7 Aug 1997 12:08:15 -0400 (EDT) Date: Thu, 7 Aug 1997 12:08:15 -0400 (EDT) From: Don Wells Message-Id: <199708071608.MAA14577 at fits.cv.nrao.edu> To: iaufwg at fits.cv.nrao.edu, fitsbits at fits.cv.nrao.edu Subject: Successful demonstration of DATExxxx interoperability Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Dear friends of FITS (especially the IAU FITS Working Group), I am pleased to report that the necessary interoperability demonstration of the proposed DATExxxx agreement has been achieved. Preben Grosbol used a version of MIDAS to read the FITS test file which Eric Greisen had produced with a version of AIPS. Preben then ordered MIDAS to write the data out as another FITS file, which Eric has read successfully with AIPS. The dates are consistent in the two systems and two files (see below). The original test file produced by AIPS is ftp://fits.cv.nrao.edu/fits/data/samples/year-2000/newdate.fits.gz and the version of this file produced by MIDAS is ftp://fits.cv.nrao.edu/fits/data/samples/year-2000/y2000m1.fits.gz Header listings are in files "newdate.lst" and "y2000m1.list" in the same directory. The command "grep 'DATE' newdate.lst" produces DATE-OBS= '1979-09-19' /OBSERVATION START DATE DD/MM/YY DATE-MAP= '1992-09-18' /DATE OF LAST PROCESSING DD/MM/YY HISTORY PUTHEAD DATE-OBS =' ' / old HISTORY PUTHEAD DATE-OBS ='19790919' / new DATE = '1997-07-25' / File written on yyyy-mm-dd and command "grep 'DATE' y2000m1.lst" produces DATE = '1997-07-29T14:37:32' / Date of writting: DD/MM/YY DATE-OBS= '1979-09-19' / MIDAS desc.: O_TIME(1) HISTORY PUTHEAD DATE-OBS =' ' / old HISTORY PUTHEAD DATE-OBS ='19790919' / new DATE-MAP= '1992-09-18' / DATE OF LAST PROCESSING DD/MM/YY Note that MIDAS appended a time string to the DATE value. I recommend that all FITS writing code use the new time string capability with DATE in this manner, even if they don't use it with DATE-OBS etc., because it produces a useful unique time-tag in each FITS file. Preben supplied a second FITS test file, a nice galaxy image, at ftp://fits.cv.nrao.edu/fits/data/samples/year-2000/y2000m2.fits.gz The command "grep 'DATE' y2000m2.lst" produces DATE = '1997-07-29T15:02:58' / Date of writting: DD/MM/YY DATE-OBS= '1993-05-17' / MIDAS desc.: O_TIME(1) I encourage all of you to test the FITS readers of your datasystems with these files, and to report the results to the FITS community. I will be pleased to add DATExxxx test files produced by the FITS writers of other datasystems to this directory. Regards, Don Wells (Chair, IAU FITS Working Group) -- Donald C. Wells Associate Scientist dwells at nrao.edu http://fits.cv.nrao.edu/~dwells National Radio Astronomy Observatory +1-804-296-0277 520 Edgemont Road, Charlottesville, Virginia 22903-2475 USA From owner-fitsbits Sun Aug 10 11:53:49 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id LAA04569 for fitsbits-spinner; Sun, 10 Aug 1997 11:53:49 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id LAA04566 for ; Sun, 10 Aug 1997 11:53:46 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id LAA17820 for fitsbits at majordomo.cv.nrao.edu; Sun, 10 Aug 1997 11:53:45 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id QAA26713 for ; Fri, 8 Aug 1997 16:31:54 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id QAA16349 for ; Fri, 8 Aug 1997 16:31:53 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id QAA32032; Fri, 8 Aug 1997 16:31:52 -0400 To: fitsbits at fits.cv.nrao.edu Date: 8 Aug 1997 16:04 EDT From: bschlesinger at nssdca.gsfc.nasa.gov (Barry M. Schlesinger) Message-ID: <8AUG199716041586 at nssdca.gsfc.nasa.gov> Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!europa.clark.net!128.223.220.30!logbridge.uoregon.edu!enews.sgi.com!news.sgi.com!nick.arc.nasa.gov!newsfeed.gsfc.nasa.gov!nssdca.gsfc.nasa.gov!bschlesinger Reply-To: fits at nssdca.gsfc.nasa.gov Subject: Sources of FITS Information Newsgroups: sci.astro.fits,sci.answers,news.answers Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Archive-name: astronomy/fits/info-sources Last-modified: 1997/08/08 -------- Sources of FITS Information Preface This material on sources of Flexible Image Transport System (FITS) information is posted and updated periodically by the FITS Support Office at the NASA Goddard Space Flight Center (GSFC). It discusses where general FITS information, including some answers to frequently asked questions, can be found, and provides sources for detailed information on FITS software and documentation. ------- FITS Support Office The FITS Support Office maintains a library of FITS information accessible via http://ssdoo.gsfc.nasa.gov/astro/fits/fits_home.html or ftp://nssdc.gsfc.nasa.gov/pub/fits/. The material available includes o "Definition of FITS", a codification of FITS for the NASA/Science Office of Standards and Technology (NOST), available in LaTeX, uncompressed PostScript, compressed PostScript and (often) ASCII text o "A User's Guide to FITS", published by the FITS Support Office, in LaTeX, uncompressed PostScript, and gzipped PostScript o Revisions to version 1.0 of the "Definition of FITS" covering the specification of units, which were incorporated into version 1.1 (text) o A current list of the extension type (structure) names registered with the International Astronomical Union FITS Working Group (IAUFWG) (text) o Rules for physical blocking on various media adopted by the IAUFWG (text) o The proposal under consideration by the FITS committees for a format with a four-digit year for DATExxxx keyword values (text) In the same directory but accessible directly via http://ssdoo.gsfc.nasa.gov/astro/fits/basics_info.html is the FITS Basics and Information that used to be regularly posted to sci.astro.fits and sci.data.formats. It continues to be revised to reflect current FITS developments. It contains the following material: o An overview of FITS o A list of FITS documents o A list of software packages that support FITS, including FITS <--> image converters for various platforms o A list of on-line FITS resources o A description of the FITS Support Office The hypertext version provides links to many of the documents, software, and network locations listed. The text version provides information on how to obtain much of this material. There is also a hypertext version of the List of Registered Extensions. Links from the Web page and subdirectories of the ftp directory contain o Software developed by the FITS Support Office. o Error test files: primary HDUs useful for testing the ability of software designed to read FITS files to cope with files that have errors or are non-standard. These files should be downloaded in binary form. Printed copies of the material in the FITS directory can be obtained from the Coordinated Request and User Support Office (CRUSO): (Postal) Coordinated Request and User Support Office Code 633 National Space Science Data Center NASA Goddard Space Flight Center Greenbelt MD 20771 USA (Electronic mail) request at nssdca.gsfc.nasa.gov (Telephone) +1-301-286-6695 8:00 A. M. - 4:30 P.M. U. S. Eastern Time (-0500 from the last Sunday in October through the first Saturday in April; -0400 the remainder of the year) When no one is available, messages can be left on voice mail. (FAX) +1-301-286-1635 ------- National Radio Astronomy Observatory (NRAO) A FITS Archive can be found at URL http://fits.cv.nrao.edu/ or at ftp://fits.cv.nrao.edu/fits, located at NRAO. This machine supports a WAIS server named nrao-fits which has an index of all of the FITS-related text files in the archive; the file nrao-fits.src is available at ftp://fits.cv.nrao.edu/fits/wais-sources/nrao-fits.src. Some of the more noteworthy materials in this archive are o Text of any detailed proposals currently being discussed by the FITS committees o Drafts of other formally proposed additions to the FITS standard and of potential future proposals o A collection of documents on World Coordinate Systems, including the current draft proposal o Conventions specific to particular projects or disciplines o Software for various environments and Usenet postings about code o Sample data and special test files designed to measure the ability of a FITS reader to handle a wide variety of FITS files o Archives of traffic on FITS-related newsgroups and exploders A separate NRAO site, http://www.cv.nrao.edu/~bcotton/fitsview.html, provides information on the FITSview family of software packages for display of FITS images on Microsoft Windows 3.1 and Windows 95, Apple Macintosh, and Unix/X-Windows, with links to the software. It also links to a number of sources of astronomical FITS images. ------- HEASARC The NASA/Goddard High Energy Astrophysics Science Archive Research Center (HEASARC) Web server at http://heasarc.gsfc.nasa.gov/docs/heasarc/fits.html and the anonymous ftp access through ftp://heasarc.gsfc.nasa.gov/fits_info/ provide FITS material. HEASARC has developed the FITSIO package of software routines for easily reading and writing FITS files, with FORTRAN and C versions available, portable to a wide variety of machines. There are also the FTOOLS collection of software tools, the VERIFITS FITS conformance verifier, and the fv FITS file viewer and editor. HEASARC software is available directly through http://heasarc.gsfc.nasa.gov/docs/heasarc/tech_res_software.html or ftp://heasarc.gsfc.nasa.gov/fits_info/software/ . The HEASARC server also provides information from the HEASARC FITS Working Group, (HFWG) the internal legislative body on FITS-related matters within the Office of Guest Investigator Programs (OGIP) at NASA/GSFC, at http://heasarc.gsfc.nasa.gov/docs/heasarc/ofwg/ofwg_intro.html or at ftp://heasarc.gsfc.nasa.gov/fits_info/ in the directories ofwg_minutes and ofwg_recomm. The HFWG has developed a number of FITS conventions that are more specific than the requirements of the FITS standards. Proposed conventions are publicized to the FITS community as a whole, with the goal of collaborative development of a set of conventions that will be accepted throughout the community as well as within OGIP/HEASARC. ------- Direct questions about this posting to Barry M. Schlesinger Coordinator, FITS Support Office Electronic mail: fits at nssdca.gsfc.nasa.gov Telephone: +1-301-286-2899 The FITS Support Office is operated under the guidance of the NASA/GSFC Astrophysics Data Facility. From owner-fitsbits Mon Aug 11 16:48:37 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id QAA11032 for fitsbits-spinner; Mon, 11 Aug 1997 16:48:37 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id QAA11029 for ; Mon, 11 Aug 1997 16:48:34 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id QAA19209 for fitsbits at majordomo.cv.nrao.edu; Mon, 11 Aug 1997 16:48:33 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id QAA10952 for ; Mon, 11 Aug 1997 16:35:19 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id QAA19180 for ; Mon, 11 Aug 1997 16:35:17 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id QAA28834; Mon, 11 Aug 1997 16:35:16 -0400 To: fitsbits at fits.cv.nrao.edu Date: Mon, 11 Aug 1997 16:35:13 -0400 From: Bob Garwood Message-ID: <33EF7781.1DC11185 at nrao.edu> Organization: National Radio Astronomy Observatory Path: newsfeed.cv.nrao.edu!not-for-mail Subject: Floating point NaN values as Keywords Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Just as it is useful to store NaN (not a number) values in binary tables to indicate an invalid number, it would be equally useful to have some convention for indicating a NaN as a keyword value. FORTRAN-77 doesn't say anything about NaNs so this would appear to be not allowed. Nevertheless, it would be useful. The only alternative when a certain keyword is expected to be there is to invent a value that is a lie (which leaves more than just a bad taste in my mouth) or to not write that keyword (which leaves someone down the road wondering if the keyword was left out because it was unknown or some writer was just sloppy and lost that particular keyword, and could be a particular problem if some convention requires that that keyword be present). In the Single Dish FITS convention that has been firming up for years (often called the Green Bank convention, at least in part), columns in a binary table which have a constant value and which have a name with 8 characters or less can be represented as keywords (called virtual columns). Without the ability to write a NaN as a keyword, columns which are constant NaNs could not be made virtual in this convention. One data point for consideration: Pense's cfitsio library will write out "NaN" when given a keyword value that is a NaN, at least under Linux and Solaris. What does anyone else feel about NaN values and keywords? Cheers, Bob Garwood bgarwood at nrao.edu From owner-fitsbits Tue Aug 12 11:18:17 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id LAA15117 for fitsbits-spinner; Tue, 12 Aug 1997 11:18:17 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id LAA15114 for ; Tue, 12 Aug 1997 11:18:14 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id LAA20051 for fitsbits at majordomo.cv.nrao.edu; Tue, 12 Aug 1997 11:18:13 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id AAA12649 for ; Tue, 12 Aug 1997 00:48:28 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id AAA19625 for ; Tue, 12 Aug 1997 00:48:26 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id AAA16718; Tue, 12 Aug 1997 00:48:25 -0400 To: fitsbits at fits.cv.nrao.edu Date: 12 Aug 1997 04:34:14 GMT From: seaman at noao.edu (Rob Seaman) Message-ID: <5sop46$egk$1 at noao.tuc.noao.edu> Organization: National Optical Astronomy Observatories, Tucson, AZ, USA Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!howland.erols.net!infeed2.internetmci.com!newsfeed.internetmci.com!ncar!noao!seaman References: <33EF7781.1DC11185 at nrao.edu> Subject: Re: Floating point NaN values as Keywords Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Bob Garwood writes: > Pense's cfitsio library will write out "NaN" when given a keyword > value that is a NaN, at least under Linux and Solaris. Is this formatted as a string in this case, or do the NaN "digits" appear as a real valued keyword? The latter would be illegal. Any viable solution will likely have to agree with the original FITS FORTRAN-derived format rules. The golden "once FITS, always FITS" rule doesn't actually forbid expanding the definition of a real number by adding newly allowed values - but this seems like a mighty big change. Note that restricting (as opposed to "deprecating") previously allowed values would be forbidden, on the other hand.) > What does anyone else feel about NaN values and keywords? Is NaN the only IEEE feature that needs to be considered? The mapping between a binary IEEE data representation and an ASCII FITS keyword is unlikely to ever be perfect. I see no easy way to support NaN for any keywords that are required to be type real by the standard (e.g., BSCALE/BZERO). FITS "user" keywords are not explicitly typed in general, on the other hand, and an otherwise real keyword could be retyped as a string to express a NaN. This presents a bit of a complication for software to handle, but in practice shouldn't be too big a deal. Many packages will likely parse a real/string value correctly already - assuming they can handle NaN's, that is. Only applications that need to read that particular keyword will care in any event. Rob Seaman -- seaman at noao.edu, http://iraf.noao.edu/~seaman NOAO, 950 N Cherry Ave, Tucson AZ 85719, 520-318-8248 PGP: 98 8D 8B 49 74 9A 41 88 3A 43 87 54 51 BF 30 4B From owner-fitsbits Tue Aug 12 15:58:58 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id PAA16072 for fitsbits-spinner; Tue, 12 Aug 1997 15:58:58 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id PAA16069 for ; Tue, 12 Aug 1997 15:58:54 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id PAA20388 for fitsbits at majordomo.cv.nrao.edu; Tue, 12 Aug 1997 15:58:53 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id MAA15335 for ; Tue, 12 Aug 1997 12:20:47 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id MAA20112 for ; Tue, 12 Aug 1997 12:20:46 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id MAA15682; Tue, 12 Aug 1997 12:20:45 -0400 To: fitsbits at fits.cv.nrao.edu Date: Tue, 12 Aug 1997 12:20:42 -0400 From: Bob Garwood Message-ID: <33F08D5A.242D37B3 at nrao.edu> Organization: National Radio Astronomy Observatory Path: newsfeed.cv.nrao.edu!not-for-mail References: <33EF7781.1DC11185 at nrao.edu> <5sop46$egk$1 at noao.tuc.noao.edu> Subject: Re: Floating point NaN values as Keywords Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Rob Seaman wrote: > > Bob Garwood writes: > > > Pense's cfitsio library will write out "NaN" when given a keyword > > value that is a NaN, at least under Linux and Solaris. > > Is this formatted as a string in this case, or do the NaN "digits" > appear as a real valued keyword? The latter would be illegal. It apears as a real valued keyword, so, I agree, this seems illegal. Someone here just point out to me that the FITS definition allows for the following construct as valid FITS: K = / i.e. no value given for the keyword. Apparently in the FORTRAN-77 list-directed read this would be interpretted as leaving the value of K unchanged. For my purposes, where the desire is to provide a required keyword for which, in some specific cases, the value of this keyword is unknown, the above is suficient, I think to convey that. It doesn't provide a bogus value (i.e. it isn't a lie) and it also doesn't omit the keyword (leaving the reader to wonder if that was an intentional omission or not). -Bob Garwood From owner-fitsbits Tue Aug 12 16:01:45 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id QAA16098 for fitsbits-spinner; Tue, 12 Aug 1997 16:01:45 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id QAA16094 for ; Tue, 12 Aug 1997 16:01:41 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id QAA20397 for fitsbits at majordomo.cv.nrao.edu; Tue, 12 Aug 1997 16:01:40 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id OAA15698 for ; Tue, 12 Aug 1997 14:02:38 -0400 Received: from palantir.cv.nrao.edu (root at palantir.cv.nrao.edu [192.33.115.254]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id OAA20271 for ; Tue, 12 Aug 1997 14:02:37 -0400 (EDT) Received: (from root at localhost) by palantir.cv.nrao.edu (8.8.5/8.8.5) id OAA09037 for fitsbits at fits.cv.nrao.edu; Tue, 12 Aug 1997 14:01:02 -0400 Received: from xebec.gsfc.nasa.gov(128.183.126.205) by palantir.cv.nrao.edu via smap (V1.3) id sma009030; Tue Aug 12 14:01:00 1997 Received: (from arots at localhost) by xebec.gsfc.nasa.gov (LHEA9504/950407.s1) id OAA12745; Tue, 12 Aug 1997 14:00:02 -0400 From: Arnold Rots Message-Id: <199708121800.OAA12745 at xebec.gsfc.nasa.gov> Subject: Re: Floating point NaN values as Keywords To: seaman at noao.edu (Rob Seaman) Date: Tue, 12 Aug 1997 14:00:01 -0400 (EDT) Cc: fitsbits at fits.cv.nrao.edu In-Reply-To: <5sop46$egk$1 at noao.tuc.noao.edu> from "Rob Seaman" at Aug 12, 97 04:34:14 am X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk > > Bob Garwood writes: > > > Pense's cfitsio library will write out "NaN" when given a keyword > > value that is a NaN, at least under Linux and Solaris. > > Is this formatted as a string in this case, or do the NaN "digits" > appear as a real valued keyword? The latter would be illegal. > > Any viable solution will likely have to agree with the original FITS > FORTRAN-derived format rules. The golden "once FITS, always FITS" rule > doesn't actually forbid expanding the definition of a real number by > adding newly allowed values - but this seems like a mighty big change. > Note that restricting (as opposed to "deprecating") previously allowed > values would be forbidden, on the other hand.) However, if one wants to be able to distinguish a NaN unambiguously from the string value "'NaN'", then one would have to extend the definition of a float to include the "digits" NaN (case significant?). I understand that this is a major change that may have to get the IAU FWG blessing, but if one does this, one might as well do it right. > > > What does anyone else feel about NaN values and keywords? > > Is NaN the only IEEE feature that needs to be considered? The mapping > between a binary IEEE data representation and an ASCII FITS keyword is > unlikely to ever be perfect. Indefs and Infins? > > I see no easy way to support NaN for any keywords that are required to > be type real by the standard (e.g., BSCALE/BZERO). FITS "user" keywords > are not explicitly typed in general, on the other hand, and an otherwise > real keyword could be retyped as a string to express a NaN. > > This presents a bit of a complication for software to handle, but in > practice shouldn't be too big a deal. Many packages will likely parse > a real/string value correctly already - assuming they can handle NaN's, > that is. Only applications that need to read that particular keyword > will care in any event. To complicate matters further, there is the precedent of arrays of numbers encoded as comma-separated lists in a string ... Retyping a float keyword as a string could work, but requires two things: the string should not represent a number (such as '42') and only NaNs could be thus encoded. > > Rob Seaman > -- > seaman at noao.edu, http://iraf.noao.edu/~seaman > NOAO, 950 N Cherry Ave, Tucson AZ 85719, 520-318-8248 > PGP: 98 8D 8B 49 74 9A 41 88 3A 43 87 54 51 BF 30 4B > > - Arnold Rots From owner-fitsbits Wed Aug 13 12:15:44 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id MAA20621 for fitsbits-spinner; Wed, 13 Aug 1997 12:15:44 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id MAA20618 for ; Wed, 13 Aug 1997 12:15:40 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id MAA21535 for fitsbits at majordomo.cv.nrao.edu; Wed, 13 Aug 1997 12:15:39 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id JAA19966 for ; Wed, 13 Aug 1997 09:56:23 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id JAA21364 for ; Wed, 13 Aug 1997 09:56:22 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id JAA08928; Wed, 13 Aug 1997 09:56:20 -0400 To: fitsbits at fits.cv.nrao.edu Date: 13 Aug 1997 09:36 EDT From: bschlesinger at nssdca.gsfc.nasa.gov (Barry M. Schlesinger) Message-ID: <13AUG199709361040 at nssdca.gsfc.nasa.gov> Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!news.maxwell.syr.edu!news.idt.net!news-peer.gsl.net!news.gsl.net!news.he.net!nick.arc.nasa.gov!newsfeed.gsfc.nasa.gov!nssdca.gsfc.nasa.gov!bschlesinger References: <33EF7781.1DC11185 at nrao.edu> Subject: Re: Floating point NaN values as Keywords Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk In article <33EF7781.1DC11185 at nrao.edu>, Bob Garwood writes... >Just as it is useful to store NaN (not a number) values in >binary tables to indicate an invalid number, it would be equally >useful to have some convention for indicating a NaN as >a keyword value. > >FORTRAN-77 doesn't say anything about NaNs so this would >appear to be not allowed. > >Nevertheless, it would be useful. > >The only alternative when a certain keyword is expected >to be there is to invent a value that is a lie ... or to not write >that keyword ... >In the Single Dish FITS convention... >that has been firming >up for years (often called the Green Bank convention, at least >in part), columns in a binary table which have a constant >value and which have a name with 8 characters or less can >be represented as keywords (called virtual columns). >Without the ability to write a NaN as a keyword, columns which >are constant NaNs could not be made virtual in this convention. > >... > > Pense's cfitsio library will write out "NaN" when given a >keyword value that is a NaN, at least under Linux and Solaris. > > >What does anyone else feel about NaN values and keywords? > As NOST 100-1.1 puts it, "The value shall be the ASCII text representation of a string or constant." What is the ASCII representation of a NaN? Barry Schlesinger FITS Support Office GSFC/ADF From owner-fitsbits Wed Aug 13 12:45:38 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id MAA20802 for fitsbits-spinner; Wed, 13 Aug 1997 12:45:38 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id MAA20799 for ; Wed, 13 Aug 1997 12:45:34 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id MAA21573 for fitsbits at majordomo.cv.nrao.edu; Wed, 13 Aug 1997 12:45:33 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id MAA20789 for ; Wed, 13 Aug 1997 12:45:07 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id MAA21564 for ; Wed, 13 Aug 1997 12:45:05 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id MAA15957; Wed, 13 Aug 1997 12:45:04 -0400 To: fitsbits at fits.cv.nrao.edu Date: Wed, 13 Aug 1997 10:11:18 -0600 From: Chris Flatters Message-ID: <33F1DCA6.70 at nrao.edu> Organization: NRAO Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!howland.erols.net!infeed1.internetmci.com!newsfeed.internetmci.com!199.60.229.3!newsfeed.direct.ca!news.he.net!news.mhpcc.edu!lynx.unm.edu!chaos.aoc.nrao.edu!usenet References: <33EF7781.1DC11185 at nrao.edu> <13AUG199709361040 at nssdca.gsfc.nasa.gov> Subject: Re: Floating point NaN values as Keywords Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Barry M. Schlesinger wrote: > > > As NOST 100-1.1 puts it, "The value shall be the ASCII text > representation of a string or constant." What is the ASCII > representation of a NaN? There is no standard ASCII representation of a NaN nor even a requirement that there be one. The relevent paragraph of IEEE-754 states If decimal to binary conversion over/underflows, the response is as specified in Section 7 [trap or +/- infinity depending on mode]. Over/underflow and NaNs and infinities encountered during binary to decimal conversion should be indicated to the user by appropriate strings. NaNs encoded in decimal strings are not specified in this standard. [Section 5.6] Summarizing: there a recommendation (not a requirement --- note the use of "should" rather than "shall") that NaNs be represented be some "appropriate string" but there is no specification for the form of that string; if this recommendation is followed there is no requirement that such a string should be recognized if encountered when reading a floating-point number. In practice, textual representations of NaNs show significant variability including NaN, -NaN, and QNaN as well as longer representations. Without a specific agreement on the format to be used for indeterminate values of FITS keywords it would not be advisable to use such values. Chris Flatters cflatter at nrao.edu From owner-fitsbits Sat Aug 16 16:59:55 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id QAA04988 for fitsbits-spinner; Sat, 16 Aug 1997 16:59:55 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id QAA04985 for ; Sat, 16 Aug 1997 16:59:51 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id QAA01978 for fitsbits at majordomo.cv.nrao.edu; Sat, 16 Aug 1997 16:59:50 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id QAA04973 for ; Sat, 16 Aug 1997 16:58:35 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id QAA01969 for ; Sat, 16 Aug 1997 16:58:34 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id QAA17837; Sat, 16 Aug 1997 16:58:33 -0400 To: fitsbits at fits.cv.nrao.edu Date: 16 Aug 1997 20:58:30 GMT From: dwells at nrao.edu (Don Wells) Message-ID: Organization: nrao Path: newsfeed.cv.nrao.edu!newsfeed.cv.nrao.edu!dwells Subject: Status of the year-2000 DATExxxx draft proposal Newsgroups: sci.astro.fits,sci.astro,sci.astro.amateur Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Dear friends of FITS, With strong support from the IAU FITS Working Group, I am issuing the following statement to inform all of you that the time has come to begin implementing the new DATExxxx syntax in your FITS reading and writing software: -=-=-=-=-=-=- Status of the year-2000 DATExxxx draft proposal Don Wells (Chair, IAU FITS Working Group) 1997-08-16 The IAU FITS Working Group is currently considering the draft document ftp://fits.cv.nrao.edu/fits/documents/proposals/year2000.txt as a proposed change to the FITS standards. While some details of the semantics and the wording of the proposed agreement are still being negotiated, a consensus exists that the final agreement will specify that the new date syntax DATE-OBS='1997-08-16' will replace the existing standard date syntax DATE-OBS='16/08/97' (which will remain valid for 1900-1999). The IAU-FWG expects to reach final agreement on the details of this change to the FITS standards by about 1997-10-01. Sample FITS files at ftp://fits.cv.nrao.edu/fits/data/samples/year-2000/ are available for interoperability tests. -=-=-=-=-=-=- I will be pleased to receive additional FITS files containing the new DATExxxx syntax, and will add them to directory data/samples/year-2000/. Regards, Don Wells (Chair, IAU FITS Working Group) -- Donald C. Wells Associate Scientist dwells at nrao.edu http://fits.cv.nrao.edu/~dwells National Radio Astronomy Observatory +1-804-296-0277 520 Edgemont Road, Charlottesville, Virginia 22903-2475 USA From owner-fitsbits Mon Aug 18 11:50:41 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id KAA30209 for fitsbits-spinner; Mon, 18 Aug 1997 10:08:40 -0400 Received: from cv3.cv.nrao.edu (cv3.cv.nrao.edu [192.33.115.2]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id KAA30050 for ; Mon, 18 Aug 1997 10:08:07 -0400 Received: from fits.cv.nrao.edu (dwells at fits.cv.nrao.edu [192.33.115.8]) by cv3.cv.nrao.edu (8.8.5/8.8.5/CV-2.5) with ESMTP id NAA16004 for ; Sun, 17 Aug 1997 13:08:17 -0400 (EDT) Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id NAA02990 for fitsbits at majordomo.cv.nrao.edu; Sun, 17 Aug 1997 13:08:14 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id CAA26649 for ; Sun, 17 Aug 1997 02:37:26 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id CAA02630 for ; Sun, 17 Aug 1997 02:37:24 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id CAA07468; Sun, 17 Aug 1997 02:37:22 -0400 To: fitsbits at fits.cv.nrao.edu Date: Sun, 17 Aug 1997 06:41:29 +0100 From: Stephen Tonkin Message-ID: Organization: A.U. Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!howland.erols.net!cpk-news-hub1.bbnplanet.com!news.bbnplanet.com!dispatch.news.demon.net!demon!aegis1.demon.co.uk!astro References: Subject: Re: Status of the year-2000 DATExxxx draft proposal Newsgroups: sci.astro.fits,sci.astro,sci.astro.amateur Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Don Wells wrote: >With strong support from the IAU FITS Working Group, I am issuing the >following statement to inform all of you that the time has come to >begin implementing the new DATExxxx syntax in your FITS reading and >writing software: This appears to comply with ISO 8601 -- something we should *all* be trying to follow. For more details on this ISO, and other aspects of the "Year 2000 problem", take a look at: http://www.aegis1.demon.co.uk/y2k.htm Remove *spoiler to send email -- Stephen Tonkin | UK Amateur Telescope Making Pages | (N50.9105 W1.829) From owner-fitsbits Sat Aug 30 15:39:31 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id PAA18395 for fitsbits-spinner; Sat, 30 Aug 1997 15:39:31 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id PAA18392 for ; Sat, 30 Aug 1997 15:39:28 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id PAA13522 for fitsbits at majordomo.cv.nrao.edu; Sat, 30 Aug 1997 15:39:27 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id PAA25499 for ; Tue, 19 Aug 1997 15:16:47 -0400 Received: from palantir.cv.nrao.edu (tismail at palantir.cv.nrao.edu [192.33.115.254]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id PAA00476 for ; Tue, 19 Aug 1997 15:16:46 -0400 (EDT) Received: (from tismail at localhost) by palantir.cv.nrao.edu (8.8.5/8.8.5) id PAA06830 for ; Tue, 19 Aug 1997 15:15:48 -0400 Received: from wheelo.gsfc.nasa.gov(128.183.50.20) by palantir.cv.nrao.edu via smap (V1.3) id sma006824; Tue Aug 19 15:15:31 1997 Received: from tetra.gsfc.nasa.gov (tetra.gsfc.nasa.gov [128.183.127.109]) by wheelo.gsfc.nasa.gov (8.8.5/8.8.4) with SMTP id PAA02523 for ; Tue, 19 Aug 1997 15:15:52 -0400 (EDT) Received: by tetra.gsfc.nasa.gov (SMI-8.6/SMI-SVR4) id PAA04727; Tue, 19 Aug 1997 15:15:52 -0400 Date: Tue, 19 Aug 1997 15:15:52 -0400 From: pence at tetra.gsfc.nasa.gov (William Pence) Message-Id: <199708191915.PAA04727 at tetra.gsfc.nasa.gov> To: fitsbits at fits.cv.nrao.edu Subject: Re: Floating point NaN values as Keywords Cc: pence at tetra.gsfc.nasa.gov X-Sun-Charset: US-ASCII Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Bob Garwood wrote: > Pence's cfitsio library will write out "NaN" when given a > keyword value that is a NaN, at least under Linux and Solaris. This behavior of CFITSIO is not intentional, and is just an accidental result of a 'non-standard' feature in these C compilers. I believe these keywords are illegal according to the FITS standard, so CFITSIO should return an error if one attempts to write a NaN value to a keyword. I'll try to trap these cases in the next release of CFITSIO. As to the question of how to represent an undefined keyword value (which is what a NaN represents) I would support the form illustrated in Garwood's follow-up message: > Someone here just point out to me that the FITS definition allows > for the following construct as valid FITS: > > K = / > > i.e. no value given for the keyword. Apparently in the FORTRAN-77 > list-directed read this would be interpretted as leaving the > value of K unchanged. This usage has apparently always been legal in FITS (since it follows the rules for list-directed Fortran-77 reads) but has not been widely known. (It is mentioned in the draft of the next version of the FITS Standard, however). The latest versions of CFITSIO and FITSIO support this usage. -Bill Pence HEASARC/GSFC From owner-fitsbits Sat Aug 30 15:57:12 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id PAA18494 for fitsbits-spinner; Sat, 30 Aug 1997 15:57:12 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id PAA18491 for ; Sat, 30 Aug 1997 15:57:09 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id PAA13537 for fitsbits at majordomo.cv.nrao.edu; Sat, 30 Aug 1997 15:57:08 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id EAA05581 for ; Thu, 28 Aug 1997 04:28:08 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id EAA09932 for ; Thu, 28 Aug 1997 04:28:07 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id EAA30683; Thu, 28 Aug 1997 04:28:05 -0400 To: fitsbits at fits.cv.nrao.edu Date: Thu, 28 Aug 1997 10:21:25 +0200 From: "Michael Wichmann" Message-ID: <5u3chc$i1k$1 at news.metronet.de> Organization: Metronet Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!howland.erols.net!EU.net!main.Germany.EU.net!news-koe1.dfn.de!RRZ.Uni-Koeln.DE!newsfeed.metronet.de!news.metronet.de!not-for-mail Subject: Application example for FITS Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Hi everyone ! I'm looking for a more comprehensive description of the FITS format than the official NOST definition. This maybe simply a junk of code that deals with an FITS image. If somebody has any information about the FITSystem I would be glad if you let me know. Tnx, Mike From owner-fitsbits Sat Aug 30 16:00:49 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id QAA18533 for fitsbits-spinner; Sat, 30 Aug 1997 16:00:49 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id QAA18530 for ; Sat, 30 Aug 1997 16:00:46 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id QAA13547 for fitsbits at majordomo.cv.nrao.edu; Sat, 30 Aug 1997 16:00:45 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id LAA07102 for ; Thu, 28 Aug 1997 11:52:29 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id LAA10367 for ; Thu, 28 Aug 1997 11:52:28 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id LAA16768; Thu, 28 Aug 1997 11:52:27 -0400 To: fitsbits at fits.cv.nrao.edu Date: 28 Aug 1997 15:44:07 GMT From: seaman at noao.edu (Rob Seaman) Message-ID: <5u46c7$ldb$1 at noao.tuc.noao.edu> Organization: National Optical Astronomy Observatories, Tucson, AZ, USA Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!howland.erols.net!cs.utexas.edu!ennfs.eas.asu.edu!noao!seaman References: <5u3chc$i1k$1 at news.metronet.de> Subject: Re: Application example for FITS Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk "Michael Wichmann" writes: > I'm looking for a more comprehensive description of the FITS format > than the official NOST definition. This maybe simply a junk of code > that deals with an FITS image. If somebody has any information about > the FITSystem I would be glad if you let me know. Take a look at: http://legacy.gsfc.nasa.gov/docs/software/fitsio/fitsio.html A couple of general FITS pointers are: http://www.gsfc.nasa.gov/astro/fits/basics_info.html http://fits.nrao.edu The real answer to your question is that there is no more comprehensive description of fits than the standards as published in the journals and adopted by the IAU. The NOST document is the NASA codification of the original standards (and may be adopted by the IAU itself). If you code accurately to the standard, your resulting data structures will be readable by other conforming FITS software. Note that a FITS User's Guide is also available from: http://www.gsfc.nasa.gov/astro/fits/fits_home.html that expands on various issues, but the text of the User's Guide is not part of the official standard. This is unlike other data formats that are defined by a changing software interface. In this case, the best one can hope for is to agree to some particular version level of the software, and to also hope that the interface continues to support your data format version(s) indefinitely. Rob Seaman -- seaman at noao.edu, http://iraf.noao.edu/~seaman NOAO, 950 N Cherry Ave, Tucson AZ 85719, 520-318-8248 PGP: 98 8D 8B 49 74 9A 41 88 3A 43 87 54 51 BF 30 4B From owner-fitsbits Sat Aug 30 16:13:30 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id QAA18606 for fitsbits-spinner; Sat, 30 Aug 1997 16:13:30 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id QAA18603 for ; Sat, 30 Aug 1997 16:13:27 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id QAA13566 for fitsbits at majordomo.cv.nrao.edu; Sat, 30 Aug 1997 16:13:26 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id LAA17602 for ; Sat, 30 Aug 1997 11:48:55 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id LAA13273 for ; Sat, 30 Aug 1997 11:48:53 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id LAA06651; Sat, 30 Aug 1997 11:48:53 -0400 To: fitsbits at fits.cv.nrao.edu Date: 30 Aug 1997 15:35:28 GMT From: Rob Seaman Message-ID: <5u9ek0$39s$1 at noao.tuc.noao.edu> Organization: National Optical Astronomy Observatories Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!agate!newsfeed.kornet.nm.kr!howland.erols.net!cs.utexas.edu!ennfs.eas.asu.edu!noao!caliche.tuc.noao.edu!seaman Subject: Y2K TCL style Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Comp.risks (RISKS DIGEST 19.35) had an interesting Y2K message today: Date: Tue, 26 Aug 1997 21:09:43 +0100 (BST) From: Lloyd Wood Subject: Tcl 8.0 Y2K Risk Sun's scripting division has released Tcl 8.0, a fashionable bytecode compiler reworking of the Tcl interpreter to help Tcl scale better. Making it compilable required some changes in semantics, but there were some other changes as well. In particular, http://sunscript.sun.com/TclTkCore/8.0.html Notes: There are also a few other minor incompatibilities in Tcl 8.0 and Tk 8.0: [..] 2.2-digit years are now parsed differently by the clock command to handle year 2000 issues better (years 00-38 are treated as 2000-2038 instead of 1900-1938). Supporting two-digit years in the first place was risky enough, but this change is bound to catch a lot of people out. It looks like the millennium problem may have come early for cutting-edge Tcl scripters with legacy code. PGP It's good to see that other folks are paying attention to the problem. Note, however, the differences between the FITS solution and this: 1) FITS has resolved the existing ambiguity of two-digit years by clarifying them as explicitly twentieth century. 2) FITS has actually fixed the problem (at least until Y10K). (Comparing FITS and TCL is otherwise comparing apples and oranges, of course.) The moderated, high S/N Risks Digest is available via mailing list or as the comp.risks newsgroup. Back issues are available via ftp or from: http://catless.ncl.ac.uk/Risks General information is available from: http://www.CSL.sri.com/risksinfo.html Rob Seaman --- seaman at noao.edu, http://iraf.noao.edu/~seaman NOAO, 950 N Cherry Ave, Tucson AZ 85719, 520-318-8248 PGP: 98 8D 8B 49 74 9A 41 88 3A 43 87 54 51 BF 30 4B From owner-fitsbits Sat Aug 30 16:13:53 1997 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id QAA18617 for fitsbits-spinner; Sat, 30 Aug 1997 16:13:53 -0400 Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id QAA18614 for ; Sat, 30 Aug 1997 16:13:49 -0400 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id QAA13570 for fitsbits at majordomo.cv.nrao.edu; Sat, 30 Aug 1997 16:13:49 -0400 (EDT) Received: from fits.cv.nrao.edu (fits.cv.nrao.edu [192.33.115.8]) by marmoset.cv.nrao.edu (8.8.5/8.8.5) with ESMTP id MAA17652 for ; Sat, 30 Aug 1997 12:01:34 -0400 Received: from newsfeed.cv.nrao.edu (newsfeed.cv.nrao.edu [192.33.115.17]) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) with ESMTP id MAA13307 for ; Sat, 30 Aug 1997 12:01:33 -0400 (EDT) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id MAA07391; Sat, 30 Aug 1997 12:01:32 -0400 To: fitsbits at fits.cv.nrao.edu Date: 30 Aug 1997 15:44:42 GMT From: seaman at noao.edu (Rob Seaman) Message-ID: <5u9f5a$4ek$1 at noao.tuc.noao.edu> Organization: National Optical Astronomy Observatories, Tucson, AZ, USA Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!europa.clark.net!4.1.16.34!cpk-news-hub1.bbnplanet.com!news.bbnplanet.com!cs.utexas.edu!ennfs.eas.asu.edu!noao!seaman References: <5u9ek0$39s$1 at noao.tuc.noao.edu> Subject: Re: Y2K TCL style Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Sorry for the 75 character word-wrap, make that: > Date: Tue, 26 Aug 1997 21:09:43 +0100 (BST) > From: Lloyd Wood > Subject: Tcl 8.0 Y2K Risk > > There are also a few other minor incompatibilities in Tcl 8.0 and > Tk 8.0: [..] 2.2-digit years are now parsed differently by the > clock command to handle year 2000 issues better (years 00-38 are > treated as 2000-2038 instead of 1900-1938). > > Supporting two-digit years in the first place was risky enough, > but this change is bound to catch a lot of people out. > > It looks like the millennium problem may have come early for > cutting-edge Tcl scripters with legacy code. Let's see what I messed up in this newsreader... Rob -- seaman at noao.edu, http://iraf.noao.edu/~seaman NOAO, 950 N Cherry Ave, Tucson AZ 85719, 520-318-8248 PGP: 98 8D 8B 49 74 9A 41 88 3A 43 87 54 51 BF 30 4B