From owner-fitsbits Mon Feb 9 13:24:43 1998 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id NAA13791 for fitsbits-spinner; Mon, 9 Feb 1998 13:24:43 -0500 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 NAA13788 for ; Mon, 9 Feb 1998 13:24:40 -0500 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id NAA08910 for fitsbits at majordomo.cv.nrao.edu; Mon, 9 Feb 1998 13:24:39 -0500 (EST) 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 NAA13776 for ; Mon, 9 Feb 1998 13:23:35 -0500 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id NAA08899; Mon, 9 Feb 1998 13:23:33 -0500 (EST) Date: Mon, 9 Feb 1998 13:23:33 -0500 (EST) Message-Id: <199802091823.NAA08899 at fits.cv.nrao.edu> From: Don Wells MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit To: fitsbits at fits.cv.nrao.edu Subject: A warning for FITS y2k implementors Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk An implementor of FITS y2k code told me: "..there was one sort of amusing problem with the initial implementation that other systems might run into. By default with the new-style we include the time. But because of floating point rounding, the new style date would turn into previous_day:T23:59:59.99 or whatever. While this is fine for systems that read the time part of the new format, it would presumably cause systems that ignore the time part to think the date was a day earlier than it actually was.." -Don [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 Tue Feb 10 10:42:46 1998 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id KAA18633 for fitsbits-spinner; Tue, 10 Feb 1998 10:42:46 -0500 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 KAA18630 for ; Tue, 10 Feb 1998 10:42:42 -0500 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id KAA09948 for fitsbits at majordomo.cv.nrao.edu; Tue, 10 Feb 1998 10:42:41 -0500 (EST) 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 KAA18619 for ; Tue, 10 Feb 1998 10:41:18 -0500 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 KAA09937 for ; Tue, 10 Feb 1998 10:41:12 -0500 (EST) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id KAA02056; Tue, 10 Feb 1998 10:41:10 -0500 To: fitsbits at fits.cv.nrao.edu Date: Tue, 10 Feb 1998 15:40:03 +0000 From: Peter Bunclark Message-ID: <34E074D3.7C8D at ast.cam.ac.uk> Organization: Royal Greenwich Observatory Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!news-peer.gip.net!news-raspail.gip.net!news.gsl.net!gip.net!newsfeed.eerie.fr!Cabal.CESspool!bofh.vszbr.cz!lyra.csx.cam.ac.uk!not-for-mail References: <199802091823.NAA08899 at fits.cv.nrao.edu> Subject: Re: A warning for FITS y2k implementors Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Looks suspiciously like truncation rather than rounding, hence is a bug not a feature... and of course, if you choose to read the date but not the time you must surely expect up to 24-hour quantisation errors? It's a bit like reading a floating-point value up to the decimal point and ignoring the rest! Peter. Don Wells wrote: > > An implementor of FITS y2k code told me: > > "..there was one sort of amusing problem with the initial > implementation that other systems might run into. By default with the > new-style we include the time. But because of floating point rounding, > the new style date would turn into previous_day:T23:59:59.99 or > whatever. While this is fine for systems that read the time part of > the new format, it would presumably cause systems that ignore the time > part to think the date was a day earlier than it actually was.." > > -Don [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 Tue Feb 10 14:02:54 1998 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id OAA19374 for fitsbits-spinner; Tue, 10 Feb 1998 14:02:54 -0500 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 OAA19371 for ; Tue, 10 Feb 1998 14:02:51 -0500 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id OAA10234 for fitsbits at majordomo.cv.nrao.edu; Tue, 10 Feb 1998 14:02:49 -0500 (EST) 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 OAA19360 for ; Tue, 10 Feb 1998 14:01:48 -0500 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 OAA10224 for ; Tue, 10 Feb 1998 14:01:43 -0500 (EST) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id OAA12631; Tue, 10 Feb 1998 14:01:41 -0500 To: fitsbits at fits.cv.nrao.edu Date: 10 Feb 1998 18:48:43 GMT From: thompson at orpheus.nascom.nasa.gov (William Thompson) Message-ID: <6bq7eb$l0o at post.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!128.158.254.10!news.msfc.nasa.gov!centauri.hq.nasa.gov!newsfeed.gsfc.nasa.gov!orpheus.nascom.nasa.gov!thompson References: <199802091823.NAA08899 at fits.cv.nrao.edu> Subject: Re: A warning for FITS y2k implementors Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Don Wells writes: >An implementor of FITS y2k code told me: > "..there was one sort of amusing problem with the initial > implementation that other systems might run into. By default with the > new-style we include the time. But because of floating point rounding, > the new style date would turn into previous_day:T23:59:59.99 or > whatever. While this is fine for systems that read the time part of > the new format, it would presumably cause systems that ignore the time > part to think the date was a day earlier than it actually was.." Something else that implementers of the new standard should be aware of is that under certain circumstances, a time such as 1997-06-30T23:59:60.999 could also be a valid time string, on dates containing leap seconds. William Thompson From owner-fitsbits Tue Feb 10 16:44:52 1998 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id QAA20062 for fitsbits-spinner; Tue, 10 Feb 1998 16:44:52 -0500 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 QAA20059 for ; Tue, 10 Feb 1998 16:44:48 -0500 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id QAA10452 for fitsbits at majordomo.cv.nrao.edu; Tue, 10 Feb 1998 16:44:47 -0500 (EST) 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 QAA20050 for ; Tue, 10 Feb 1998 16:44:09 -0500 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 QAA10443 for ; Tue, 10 Feb 1998 16:44:07 -0500 (EST) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id QAA20319; Tue, 10 Feb 1998 16:44:06 -0500 To: fitsbits at fits.cv.nrao.edu Date: 10 Feb 1998 21:33:27 GMT From: seaman at noao.edu (Rob Seaman) Message-ID: <6bqh37$o8e$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!newsfeed.internetmci.com!192.52.106.6!ncar!noao!seaman References: <199802091823.NAA08899 at fits.cv.nrao.edu> <34E074D3.7C8D at ast.cam.ac.uk> Subject: Re: A warning for FITS y2k implementors Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Peter Bunclark writes: > Looks suspiciously like truncation rather than rounding, hence > is a bug not a feature... and of course, if you choose to > read the date but not the time you must surely expect up to 24-hour > quantisation errors? It's a bit like reading a floating-point value > up to the decimal point and ignoring the rest! Bundling the date and time into the same keyword is also no different in this regard than having separate DATE-OBS and UT (for instance) keywords. Code that previously generated correct UT information should still work when grafted onto the DATE-OBS keyword. If the problem is that this implementor wrote some generic routine that just divided out all of the date and time fields from one unsegmented time argument (seconds since 1970 or whatever), and that only arguments corresponding to even date numbers were being fed to the routine for some reason, resulting in the 23:59:59.9 vs. 00:00:00.0 chatter around midnight - well, this seems like an inappropriate usage. Note that there were various discussions regarding "atomic" date/time pairs when we were thrashing out the MJD and Y2K stuff. Maintaining an unsegmented time scale is a larger issue than the ISO format, and certainly than rounding or truncation errors. DATE-OBS specified as a variation of YYYY-MM-DDThh:mm:ss[.sss...] consists of seven separate time segments that have to be reliably generated from some unsegmented clock. The fractional seconds field shouldn't just be calculated, but should have some reality checks built into the logic. Obviously, the simpler sexigesimal carrying and the more complicated year- and-month dependent calendar issues have to be handled cleanly or the whole Y2K bug will recur in some other guise. Also, whatever TIMESYS is being used for the date should also be used for the time information, and the calendar and clock should be consulted simultaneously (not a trivial computer science issue). I would also hazard that if some software cares about the date, but not about the time (i.e., only cares about the time to Peter's 24 hour granularity), that a careful programmer would parse the time as well as the date, and would round to the nearest day. That FITS may now require some logic tree to decide whether the time comes from DATE-OBS or UT or whatever other keyword is just an added expense of doing FITS now that we've added this feature of DATE-OBS. 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 From owner-fitsbits Wed Feb 11 09:34:22 1998 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id JAA24006 for fitsbits-spinner; Wed, 11 Feb 1998 09:34:22 -0500 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 JAA24003 for ; Wed, 11 Feb 1998 09:34:19 -0500 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id JAA11116 for fitsbits at majordomo.cv.nrao.edu; Wed, 11 Feb 1998 09:34:17 -0500 (EST) 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 SAA20408 for ; Tue, 10 Feb 1998 18:20:38 -0500 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 SAA10526 for ; Tue, 10 Feb 1998 18:20:36 -0500 (EST) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id SAA25401; Tue, 10 Feb 1998 18:20:35 -0500 To: fitsbits at fits.cv.nrao.edu Date: 10 Feb 1998 15:20:08 -0800 From: sla at ucolick.borg (Steve Allen) Message-ID: <6bqnb8$3b9$1 at dei.ucolick.org> Organization: UCO/Lick Observatory Path: newsfeed.cv.nrao.edu!newsgate.duke.edu!nntprelay.mathworks.com!logbridge.uoregon.edu!agate!news.ucsc.edu!not-for-mail References: <199802091823.NAA08899 at fits.cv.nrao.edu> <6bq7eb$l0o at post.gsfc.nasa.gov> Subject: Re: A warning for FITS y2k implementors Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk In article <6bq7eb$l0o at post.gsfc.nasa.gov>, William Thompson wrote: >under certain circumstances, a time such as > > 1997-06-30T23:59:60.999 > >could also be a valid time string, on dates containing leap seconds. There are few, if any, computer operating systems which implement a correct model of time. Therefore extreme caution should be used if new FITS date strings are to be converted to operating system clock times using standard system library procedures. -- Steve Allen UCO/Lick Observatory Santa Cruz, CA 95064 sla at ucolick.borg Voice: +1 408 459 3046 FAX (don't): +1 408 454 9863 WWW: http://www.ucolick.borg/~sla PGP public keys: see WWW Junk mail is irrelevant -- my return address has been assimilated. From owner-fitsbits Wed Feb 11 09:37:01 1998 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id JAA24025 for fitsbits-spinner; Wed, 11 Feb 1998 09:37:01 -0500 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 JAA24020 for ; Wed, 11 Feb 1998 09:36:57 -0500 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id JAA11140 for fitsbits at majordomo.cv.nrao.edu; Wed, 11 Feb 1998 09:36:56 -0500 (EST) 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 BAA21805 for ; Wed, 11 Feb 1998 01:08:39 -0500 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 BAA10773 for ; Wed, 11 Feb 1998 01:08:38 -0500 (EST) Received: (from news at localhost) by newsfeed.cv.nrao.edu (8.8.5/8.8.5) id BAA12693; Wed, 11 Feb 1998 01:08:37 -0500 To: fitsbits at fits.cv.nrao.edu Date: Tue, 10 Feb 1998 23:53:20 -0600 From: Ray Plante Message-ID: <34E13CD0.3D8C2B2D at ncsa.uiuc.edu> Organization: National Center for Supercomputing Applications Path: newsfeed.cv.nrao.edu!hearst.acc.Virginia.EDU!uunet!in5.uu.net!newsfeed.internetmci.com!128.174.5.49!vixen.cso.uiuc.edu!not-for-mail Subject: FITS & the Horizon Java Package Newsgroups: sci.astro.fits Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk Dear Colleagues, NCSA and Project 30 is pleased to announce the latest release of the Horizon Image Data Browser, version 1.3 beta, a Java package for browsing scientific images. This package may be downloaded from the Horizon IDB Home Page: http://imagelib.ncsa.uiuc.edu/Horizon Included with the latest version is a demonstration version of a FITS Image Browser. Here are some of its features: * Basic 2-D visualization of FITS images from either local disk or over the network. * Zooming and panning * Color map and transfer function control over a selectable data range * 2-D slice selection for mult-dimensional datasets * data value and world coordinate position displays, including built-in support for projected spherical systems commonly used in astronomy and earth science. You can try this viewer out from our Web page, but you can also download the Horizon package and run it as a standalone application (with improved performance). This latest version, 1.3 beta, represents the last major release that is compatible with Java 1.0.2. The next major version, 2.0 beta, will be Java 1.1 compatible. (Some minor versions may be released for bug fixes.) Some of the new features slated for the next version of the FITS Image Browser includes spreadsheet display, metadata display, color table editing, as well as support for collaboration. We encourage you to download the Horizon package and try it out. We also welcome your comments, questions, and suggestions for improvements. If you would like to be added to our mailing list for notices of new releases, just send me email at horizon at ncsa.uiuc.edu. have fun, Ray Plante NCSA Horizon Development Team From owner-fitsbits Wed Feb 11 14:41:36 1998 Received: (from majordom at localhost) by marmoset.cv.nrao.edu (8.8.5/8.8.5) id OAA25306 for fitsbits-spinner; Wed, 11 Feb 1998 14:41:36 -0500 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 OAA25302 for ; Wed, 11 Feb 1998 14:41:32 -0500 Received: (from dwells at localhost) by fits.cv.nrao.edu (8.8.5/8.8.0/CV-2.2) id OAA11443 for fitsbits at majordomo.cv.nrao.edu; Wed, 11 Feb 1998 14:41:30 -0500 (EST) 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 OAA25203 for ; Wed, 11 Feb 1998 14:12:23 -0500 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 OAA11413 for ; Wed, 11 Feb 1998 14:12:22 -0500 (EST) Received: (from tismail at localhost) by palantir.cv.nrao.edu (8.8.5/8.8.5) id OAA08103 for ; Wed, 11 Feb 1998 14:12:19 -0500 Received: from wheelo.gsfc.nasa.gov(128.183.50.20) by palantir.cv.nrao.edu via smap (V1.3) id sma008082; Wed Feb 11 14:12:16 1998 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 OAA23867 for ; Wed, 11 Feb 1998 14:11:45 -0500 (EST) Received: by tetra.gsfc.nasa.gov (SMI-8.6/SMI-SVR4) id OAA25422; Wed, 11 Feb 1998 14:11:44 -0500 Date: Wed, 11 Feb 1998 14:11:44 -0500 From: pence at tetra.gsfc.nasa.gov (William Pence) Message-Id: <199802111911.OAA25422 at tetra.gsfc.nasa.gov> To: fitsbits at fits.cv.nrao.edu Subject: New CFITSIO Release Cc: pence at tetra.gsfc.nasa.gov X-Sun-Charset: US-ASCII Sender: owner-fitsbits at marmoset.cv.nrao.edu Precedence: bulk CFITSIO 1.40 Release 11 February 1998 A new version of the CFITSIO library for reading and writing FITS format data files is now available. This release contains several significant new features that affect both C and Fortran users of the CFITSIO and FITSIO libraries: New For C Programmers: ______________________ CFITSIO can now directly read compressed FITS files in gzip (.gz) or Unix compress (.Z) formats. Users can save time and disk space by reading the compressed FITS file instead of having to uncompress it first. FITS files can be read from the 'stdin' file stream and written out to the 'stdout' stream. Just specify the input or output FITS file name as "-" (a minus sign) to use this feature. This enables a sequence of programs to pass FITS files from one to the other in memory thus speeding up the processing compared with having to create intermediate FITS files on disk. This release introduces a powerful new function called the 'iterator' for reading and writing data in FITS images or tables. This function can simplify the way software reads and writes images or columns of data, and make the code more 'object oriented' by cleanly separating the data I/O from the algorithms that operate on the data. This routine can greatly reduce the number of lines of code that are needed to read or write the data and can improve the efficiency of the program at the same time. Several sample programs that use this iterator function are included in this release. The User's Guide has been restructured to make it easier and faster to learn to use CFITIO. The most commonly used 'basic' interface routines have been grouped into one chapter for easy reference. Several new high-level routines have also been added to simplify the interface by combining what used to require several function calls into one call. New for Fortran Programmers: ___________________________ CFITSIO (written in ANSI C) now includes a set of Fortran-callable wrapper routines which effectively replace the old FITSIO Fortran library. These new CFITSIO wrappers have exactly the same calling sequence as the old FITSIO routines, so any Fortran program that currently uses the FITSIO library can now be linked instead to the CFITSIO library without any change to the source code. The main advantage of using these new CFITSIO wrappers instead of FITSIO are: - they support the new features in CFITSIO (like reading compressed FITS files, and the new iterator function) that are not available in FITSIO. - they are generally faster, by a factor of 2 in some cases. These C wrappers work on most Unix platforms, including linux, and on VMS systems. They currently are not supported on Cray supercomputers and on Windows PCs and Macs. Fortran programmers are urged to start using the CFITSIO library because support for FITSIO will now be limited to simple bug fixes and will not include any new features added to CFITSIO. Where to get it: ________________ CFITSIO is available on the web or by anonymous ftp from: http://heasarc.gsfc.nasa.gov/fitsio ftp://legacy.gsfc.nasa.gov/software/fitsio/c _________________________________________________________________________ William Pence HEASARC - High Energy Astrophysics Science Archive Research Center NASA/GSFC e-mail: pence at tetra.gsfc.nasa.gov phone: (301)286-4599