From fitsbits-request Fri Sep 2 12:01:42 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["825" "" " 2" "September" "1994" "15:28:07" "GMT" "psada" "psada at acca.nmsu.edu" "<347ga7$p5q at dns1.NMSU.Edu>" "20" "Help with IMDISP." "^From:" nil nil "9" "1994090215:28:07" "Help with IMDISP." (number " " mark " psada Sep 2 20/825 " thread-indent "\"Help with IMDISP.\"\n") nil] nil) X-VM-Message-Order: (1 2 3 4 5 6 8 9 7 10 11 13 17 18 12 15 16 14) X-VM-Summary-Format: "%n %*%a %-17.17F %-3.3m %2d %4l/%-5c %I\"%s\"\n" X-VM-Labels: nil X-VM-VHeader: ("Resent-" "From:" "Sender:" "To:" "Apparently-To:" "Cc:" "Subject:" "Date:") nil X-VM-Bookmark: 18 Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA13597; Fri, 2 Sep 94 12:01:42 EDT Return-Path: Message-Id: <347ga7$p5q at dns1.NMSU.Edu> Organization: Alternative Collegiate Computing Association Path: saips.cv.nrao.edu!hearst.acc.Virginia.EDU!darwin.sura.net!rsg1.er.usgs.gov!jobone!lynx.unm.edu!dns1.NMSU.Edu!psada From: psada at acca.nmsu.edu (psada) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Help with IMDISP. Date: 2 Sep 1994 15:28:07 GMT Hi. I am a new to FITS. I was attempting to use Version 7.9 of IMDISP, which is a FITS viewer for the PC, and had some trouble getting it to work. I downloaded and unzipped it with no apprent problems. However, when I run it the program refuses to recognize even its own sample files as having the proper format (ie. it does not load its own demo files properly) asking me for info about the file that it is obviously reading correctly from the header (I used the LABel command). I have tried this on three different PCs with the same result. Even downloaded it again. Am I missing something? Is there a flag or environment variable that I have to set? The manual does not cover anything about errors in its own sample files. Any help will be appreciated. Thank you. Pedro Valdes Sada psada at acca.nmsu.edu From fitsbits-request Mon Sep 5 09:01:32 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["529" "" " 3" "September" "1994" "01:13:04" "" "Alan Sawyer" "Alan.Sawyer at p1305.f158.n633.z3.fidonet.org" "<370_9409051914 at unique.pronet.com>" "11" "Postscript??" "^From:" nil nil "9" "1994090301:13:04" "Postscript??" (number " " mark " Alan Sawyer Sep 3 11/529 " thread-indent "\"Postscript??\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA24465; Mon, 5 Sep 94 09:01:32 EDT Return-Path: Message-Id: <370_9409051914 at unique.pronet.com> Organization: FIDONET: Coming at you from the bottom drawer of the X-FILES.... Path: saips.cv.nrao.edu!hearst.acc.Virginia.EDU!concert!gatech!swrinde!ihnp4.ucsd.edu!munnari.oz.au!jabaru.pronet.com!csource!unique!not-for-mail From: Alan.Sawyer at p1305.f158.n633.z3.fidonet.org (Alan Sawyer) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Postscript?? Date: 03 Sep 94 01:13:04 + Whilst escaping from government goons,xmosa at vega.pd.astro.it yelled out ..... xm> In article <33kg9p$lo at hugin.aau.dk>, norup at indigo (Anton Norup xm> Soerensen) writes: |> |>I would like to know of programs available for converting FITS images |>to GIF format. I will also be interested to hear of programs to |>combine three, e.g. B,V,R images to one 'true-colour' GIF image. How do I view/print these post script things too??? On an IBM, ... "I'm a citizen of Legoland travellin Incommunicado" - Fish --- * TLX v3.10 * From fitsbits-request Tue Sep 6 23:20:05 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1408" "" " 7" "September" "1994" "01:12:33" "GMT" "Carl J Lydick" "carl at SOL1.GPS.CALTECH.EDU" "<34j421$gm8 at gap.cco.caltech.edu>" "22" "Re: Postscript??" "^From:" nil nil "9" "1994090701:12:33" "Postscript??" (number " " mark " Carl J Lydick Sep 7 22/1408 " thread-indent "\"Re: Postscript??\"\n") "<370_9409051914 at unique.pronet.com>"] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA27618; Tue, 6 Sep 94 23:20:05 EDT Return-Path: Message-Id: <34j421$gm8 at gap.cco.caltech.edu> Organization: HST Wide Field/Planetary Camera Path: saips.cv.nrao.edu!hearst.acc.Virginia.EDU!concert!gatech!swrinde!ihnp4.ucsd.edu!ames!elroy.jpl.nasa.gov!netline-fddi.jpl.nasa.gov!nntp-server.caltech.edu!SOL1.GPS.CALTECH.EDU!CARL References: <370_9409051914 at unique.pronet.com> Reply-To: carl at SOL1.GPS.CALTECH.EDU From: carl at SOL1.GPS.CALTECH.EDU (Carl J Lydick) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Re: Postscript?? Date: 7 Sep 1994 01:12:33 GMT In article <370_9409051914 at unique.pronet.com>, Alan.Sawyer at p1305.f158.n633.z3.fidonet.org (Alan Sawyer) writes: =Whilst escaping from government goons,xmosa at vega.pd.astro.it yelled out ..... = xm> In article <33kg9p$lo at hugin.aau.dk>, norup at indigo (Anton Norup = xm> Soerensen) writes: |> = |>I would like to know of programs available for converting FITS images = |>to GIF format. I will also be interested to hear of programs to = |>combine three, e.g. B,V,R images to one 'true-colour' GIF image. =How do I view/print these post script things too??? On an IBM, =.... "I'm a citizen of Legoland travellin Incommunicado" - Fish You might try checking whether there's an implementation of Ghostscript for the system you use. If I recall correctly, Ghostscript is part of the GNU project, and should be available via anonymous FTP from PREP.AI.MIT.EDU [18.71.0.38]. -------------------------------------------------------------------------------- Carl J Lydick | INTERnet: CARL at SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL Disclaimer: Hey, I understand VAXen and VMS. That's what I get paid for. My understanding of astronomy is purely at the amateur level (or below). So unless what I'm saying is directly related to VAX/VMS, don't hold me or my organization responsible for it. If it IS related to VAX/VMS, you can try to hold me responsible for it, but my organization had nothing to do with it. From fitsbits-request Fri Sep 9 10:19:43 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1108" "Fri" " 9" "September" "1994" "16:19:46" "+0200" "Preben Grosbol" "pgrosbol at eso.org" "<9409091419.AA24827 at ns2.hq.eso.org>" "27" "IAU General Assembly in Den Haag" "^From:" nil nil "9" "1994090914:19:46" "IAU General Assembly in Den Haag" (number " " mark " Preben Grosbol Sep 9 27/1108 " thread-indent "\"IAU General Assembly in Den Haag\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA06572; Fri, 9 Sep 94 10:19:43 EDT Return-Path: Message-Id: <9409091419.AA24827 at ns2.hq.eso.org> From: Preben Grosbol Sender: fitsbits-request at fits.CV.NRAO.EDU To: iaufwg at fits.CV.NRAO.EDU Cc: fitsbits at fits.CV.NRAO.EDU Subject: IAU General Assembly in Den Haag Date: Fri, 09 Sep 1994 16:19:46 +0200 Dear Colleagues, There were several meeting related to the IAU FITS Working Group during the IAU General Assembly in Den Haag Aug. 17-24, 1994. The two most important points were: 1) In the business meeting of Commission 5 on 18.8, the new structure was discussed. It will associate the FITS Working Group to the Working Group on Astronomical Data. It was emphasized in the discussion that FITS WG has the authority to maintain the FITS standard and to review, approve and maintain future extensions to FITS (ref. resolution B2 of the 20th General Assembly). This infers that the FITS Group will have a very long life span to ensure the long term stability of FITS. 2) Don Wells was elected new Chairman for the FITS Working Group with Ernst Raimond as Vice-chairman. I would like to take this opportunity to thank you all for your support and work in the FITS Working Group during the last years. It is a pleasure to wish both Don and Ernst all the best with respect to the many important issues to be discussed in the coming years. Best regards Preben Grosbol From fitsbits-request Sat Sep 10 18:53:23 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2823" "Sat" "10" "September" "1994" "03:13:06" "GMT" "Don Wells" "dwells at nrao.edu" "" "63" "Re: IAU General Assembly in Den Haag" "^From:" nil nil "9" "1994091003:13:06" "IAU General Assembly in Den Haag" (number " " mark " Don Wells Sep 10 63/2823 " thread-indent "\"Re: IAU General Assembly in Den Haag\"\n") "<9409091419.AA24827 at ns2.hq.eso.org>"] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA08898; Sat, 10 Sep 94 18:53:23 EDT Return-Path: Message-Id: Organization: nrao Path: saips.cv.nrao.edu!news.cv.nrao.edu!dwells References: <9409091419.AA24827 at ns2.hq.eso.org> From: dwells at nrao.edu (Don Wells) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Re: IAU General Assembly in Den Haag Date: Sat, 10 Sep 1994 03:13:06 GMT Dear Colleagues, I thank Preben Grosbol for his good wishes for me and for Ernst Raimond as we begin our term as Chairman and Vice-Chairman of the IAU FITS Working Group. I am sure that all friends of FITS will join me in thanking Preben for his excellent leadership of the FITS community during the past twelve years. Preben's final term as Chair of the IAU-FWG ended in an especially memorable fashion, with the final acceptance of BINTABLE, IMAGE and Blocking as FITS standards. During the FITS Working Group session in Den Haag on August 23rd, Preben asked me to discuss plans for the next triennium. My vugraph was titled "IAU-FWG project list for 1994-97", with these items: 1) Review/modify the relationship between FWG and IAU-EC+Comm5 As Preben noted in his message, we made real progress on this critically important action item during the sessions at Den Haag, but several questions remain to be settled during the coming triennium. 2) Approve the NOST FITS document (need units agreement) The NOST FITS standard document has been in preparation for nearly five years with the specific goal that it should be accepted by the IAU FITS WG as the definitive standard for the FITS data format. Soon this document will be submitted to the FITS community for review. 3) Make progress toward a WCS agreement R&D efforts on "world coordinate systems" [WCS] for FITS began more than ten years ago, and interoperable implementations were deployed for radio interferometers and for the Einstein and IRAS spacecraft during the 80s. The latest releases of IRAF support WCS, and are interoperable with the prior implementations. The time appears to be ripe for the WCS agreement. The latest draft of the WCS proposal, ftp://fits.cv.nrao.edu/fits/documents/wcs/wcs.all.ps.Z, will be discussed at the FITS Birds-Of-a-Feather session at the ADASS'94 meeting in Baltimore two weeks from now. 4) Make progress toward a compression agreement I intend to encourage a renewed R&D effort on compression for FITS. 5) Register FITS with the Internet (IANA) as a MIME data type. I intend to ask the IAU-FWG for permission to apply to the Internet Assigned-Numbers Authority for a MIME [Multimedia Internet Mail Extensions] code for FITS, so that FITS file objects can be encapsulated in Email messages, and will be recognized by non-astronomy application code. I will be happy to receive comments about these action items, or about other potential projects which the FITS community could undertake. Best regards, Don Wells Chairman, 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 fitsbits-request Thu Sep 15 09:50:52 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1548" "" "15" "September" "1994" "07:01:56" "GMT" "Gregg W. Riedel" "gregg at hcirisc.cs.binghamton.edu" "" "34" "FITS data question" "^From:" nil nil "9" "1994091507:01:56" "FITS data question" (number " " mark " Gregg W. Riedel Sep 15 34/1548 " thread-indent "\"FITS data question\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA22522; Thu, 15 Sep 94 09:50:52 EDT Return-Path: Message-Id: Organization: Binghamton University, Binghamton, NY Path: saips.cv.nrao.edu!hearst.acc.Virginia.EDU!srvr1.engin.umich.edu!zip.eecs.umich.edu!yeshua.marcam.com!news.kei.com!ub!newserve!bingnews.cc.binghamton.edu!gregg From: gregg at hcirisc.cs.binghamton.edu (Gregg W. Riedel) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: FITS data question Date: 15 Sep 1994 07:01:56 GMT Hi! I'm a graduate student in computer science, with zero knowledge of astronomy. I am implementing a FITS reader for an image processing package. I have fetched a test image from the Hubble telescope of Saturn (w0ck0101t_c0h.fit), and I noticed that the FITS data is broken into 3 axes (800 x 800 x 4); these are apparently separated image planes. The questions: what kind of separation is used (RGB?, CMYK, other?), and where in the file might I find this information? Is there a standard for color images? The literature seems to point toward all "images" as being greyscale. Please forgive my misuse of FITS terminology; I understand the extreme flexibility of this format, but am solely interested in getting some pictures :) Thanks! Gregg --------------------------------------- // -------------------------------- Gregg William Riedel // Binghamton U. - MS-CS consp24 at bingsuns.pod.binghamton.edu \\ // Amiga Sr. Systems Consultant gregg at HCIRisc.cs.binghamton.edu \X/ 4000/040 ImageFX 2.0 Dev Team ----------------------------------------------------------------------------- -- --------------------------------------- // -------------------------------- Gregg William Riedel // Binghamton U. - MS-CS consp24 at bingsuns.pod.binghamton.edu \\ // Amiga Sr. Systems Consultant gregg at HCIRisc.cs.binghamton.edu \X/ 4000/040 ImageFX 2.0 Dev Team ----------------------------------------------------------------------------- From fitsbits-request Thu Sep 15 18:52:14 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1475" "" "15" "September" "1994" "22:00:27" "GMT" "Carl J Lydick" "carl at SOL1.GPS.CALTECH.EDU" "<35ag5r$9br at gap.cco.caltech.edu>" "30" "Re: FITS data question" "^From:" nil nil "9" "1994091522:00:27" "FITS data question" (number " " mark " Carl J Lydick Sep 15 30/1475 " thread-indent "\"Re: FITS data question\"\n") ""] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA23322; Thu, 15 Sep 94 18:52:14 EDT Return-Path: Message-Id: <35ag5r$9br at gap.cco.caltech.edu> Organization: HST Wide Field/Planetary Camera Path: saips.cv.nrao.edu!hearst.acc.Virginia.EDU!darwin.sura.net!rsg1.er.usgs.gov!stc06.CTD.ORNL.GOV!fnnews.fnal.gov!nntp-server.caltech.edu!SOL1.GPS.CALTECH.EDU!CARL References: Reply-To: carl at SOL1.GPS.CALTECH.EDU From: carl at SOL1.GPS.CALTECH.EDU (Carl J Lydick) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Re: FITS data question Date: 15 Sep 1994 22:00:27 GMT In article , gregg at hcirisc.cs.binghamton.edu (Gregg W. Riedel) writes: = =Hi! = I'm a graduate student in computer science, with zero knowledge of =astronomy. I am implementing a FITS reader for an image processing =package. = = I have fetched a test image from the Hubble telescope of Saturn =(w0ck0101t_c0h.fit), and I noticed that the FITS data is broken into =3 axes (800 x 800 x 4); these are apparently separated image planes. Er, no. They're images from each of four separate CCDs, not four separate colors. All images from the HST are monochromatic, in that they're images taken through a specific filter. =The questions: what kind of separation is used (RGB?, CMYK, other?), =and where in the file might I find this information? Is there a =standard for color images? The literature seems to point toward all ="images" as being greyscale. The images ARE greyscale. -------------------------------------------------------------------------------- Carl J Lydick | INTERnet: CARL at SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL Disclaimer: Hey, I understand VAXen and VMS. That's what I get paid for. My understanding of astronomy is purely at the amateur level (or below). So unless what I'm saying is directly related to VAX/VMS, don't hold me or my organization responsible for it. If it IS related to VAX/VMS, you can try to hold me responsible for it, but my organization had nothing to do with it. From fitsbits-request Thu Sep 15 22:46:55 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3201" "Fri" "16" "September" "1994" "02:34:04" "GMT" "Don Wells" "dwells at nrao.edu" "" "79" "FITS-support for Mathematica" "^From:" nil nil "9" "1994091602:34:04" "FITS-support for Mathematica" (number " " mark " Don Wells Sep 16 79/3201 " thread-indent "\"FITS-support for Mathematica\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA23438; Thu, 15 Sep 94 22:46:55 EDT Return-Path: Message-Id: Organization: nrao Path: saips.cv.nrao.edu!news.cv.nrao.edu!dwells From: dwells at nrao.edu (Don Wells) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: FITS-support for Mathematica Date: Fri, 16 Sep 1994 02:34:04 GMT I thank Fred Schwab for alerting me to the existence of this thread in newsgroup sci.math.symbolic. -Don Wells -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Newsgroups: sci.math.symbolic From: abraham at haida (Bob Abraham) Subject: MMA and FITS format images Nntp-Posting-Host: haida.dao.nrc.ca Organization: University of Victoria Date: Wed, 14 Sep 94 00:49:18 GMT Hi, Has anybody written a routine to let Mathematica read images in FITS format? If so, I'd be very grateful if you would get get in touch with me. Cheers, Bob PS. in case anybody is curious: FITS (Flexible Image Transport Format) images are mixed text/binary format files that are becoming a de-facto standard for use in astronomy. -- ----------------------------------------------------------------------------- Dr. R. G. Abraham | Internet: abraham at dao.nrc.ca Dominion Astrophysical Observatory | Bitnet: abraham at nrcdao.nrc.ca Herzberg Institute of Astrophysics | phone: (604) 363-0028 National Research Council of Canada | fax: (604) 363-0045 5071 W. Saanich Rd. | telex: 049-7295 Victoria, B.C., V8X 4M6 | CANADA | ----------------------------------------------------------------------------- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- From: elsner at avalon.msfc.nasa.gov (Ron Elsner) Newsgroups: sci.math.symbolic Subject: Reading FITS files in Mma Date: 14 Sep 1994 18:29:54 GMT Organization: NASA/MSFC I do not have a package to read all FITS files with one cammand, but I can read them treating each case separately. To read even modest sized binary files in Mathematica you MUST obtain the FastBinaryFiles MathLink Package from MathSource. You can do this via anonymous ftp to ftp.wri.com. You will have peruse their index to find it, or ask Wolfram Research Inc. After compiling the source code you can read FITS files as follows (simple example): Link to the package: SetDirectory[ "~/AXAF93Math/MathSource" ] ; link = Install[ "binary" ] Open the input file: infile = OpenReadBinary[ "image.fit" ] Read the 36 (or whatever) record, 80 columns per record, ascii header: TableForm[ hdr = Table[ FromCharacterCode[ ReadListBinary[ infile, Byte, 80 ] ], {36} ] ] Read the binary image using information from the header: image = Partition[ ReadListBinary[ infile, Int16 ], 512 ] ; In the above case, the header tells us that this is a 512 (1st axis) by 480 (2nd axis) image with 16 bits per data pixel. The array image will have dimensions 480 by 512, which you can Transpose if you like. Hope this helps. -------------------------------------------------------------------------- Ron Elsner/ES84 205-544-7741 NASA Marshall Space Flight Center 205-544-7754 (Fax) Huntsville, AL 35812 elsner at ssl.msfc.nasa.gov -- 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 fitsbits-request Fri Sep 16 01:17:08 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1066" "" "15" "September" "1994" "16:52:05" "GMT" "Bob Hanisch, ST ScI" "hanisch at stsci.edu" "<359u3l$t3p at marvel.stsci.edu>" "18" "Re: FITS data question" "^From:" nil nil "9" "1994091516:52:05" "FITS data question" (number " " mark " Bob Hanisch, ST S Sep 15 18/1066 " thread-indent "\"Re: FITS data question\"\n") ""] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA23543; Fri, 16 Sep 94 01:17:08 EDT Return-Path: Message-Id: <359u3l$t3p at marvel.stsci.edu> Organization: Space Telescope Science Institute, Baltimore MD Path: saips.cv.nrao.edu!hearst.acc.Virginia.EDU!concert!inxs.ncren.net!taco.cc.ncsu.edu!gatech!news.byu.edu!news.kei.com!MathWorks.Com!europa.eng.gtefsd.com!howland.reston.ans.net!math.ohio-state.edu!magnus.acs.ohio-state.edu!csn!ncar!noao!stsci!iris.stsci.edu!hanisch References: Reply-To: hanisch at stsci.edu From: hanisch at stsci.edu (Bob Hanisch, ST ScI) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Re: FITS data question Date: 15 Sep 1994 16:52:05 GMT Images from HST's Wide Field/Planetary Camera consist of four separate CCD frames -- these are the four images you are seeing stacked in the FITS file. They do not form a color composite or anything. The four frames are stored this way (actually, only one of several options available to HST users) purely as a matter of convenience. Each image has coordinate information in the header that describes the orientation and position of each frame. They can be pasted together brute-force to make a mosaic, but to do this properly requires eliminating region along the edges of each chip that is unilluminated, and then geometrically correcting three of the four frames to account for the slight misalignment of the detectors. _______________________________________________________________________________ Robert J. Hanisch Tel. (410)338-4910 Fax. (410)338-5090 Space Telescope Science Institute NSI: hanisch at stsci.edu [130.167.1.2] 3700 San Martin Drive DECNet: STSCIC::HANISCH [6549::] Baltimore, MD 21218 USA From dwells Mon Sep 19 10:23:57 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3630" "Mon" "19" "September" "1994" "10:23:55" "EDT" "Francois Ochsenbein" "francois at SIMBAD.u-strasbg.fr" nil "69" "FITS tables of astronomical catalogues and Units" "^From:" nil nil "9" nil nil (number " " mark " Francois Ochsenbe Sep 19 69/3630 " thread-indent "\"FITS tables of astronomical catalogues and Units\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA06134; Mon, 19 Sep 94 10:23:57 EDT Return-Path: Message-Id: <9409191423.AA06128 at fits.cv.nrao.edu> From: francois at SIMBAD.u-strasbg.fr (Francois Ochsenbein) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits Subject: FITS tables of astronomical catalogues and Units Date: Mon, 19 Sep 94 10:23:55 EDT ------- start of forwarded message (RFC 934) ------- Message-Id: <9409161659.AA26838 at SIMBAD.u-strasbg.fr> From: francois at SIMBAD.u-strasbg.fr (Francois Ochsenbein) To: fitsbits-request at fits.CV.NRAO.EDU Subject: FITS tables of astronomical catalogues and Units Date: Fri, 16 Sep 94 18:59:30 +0200 At CDS (Centre de Donnees astronomiques de Strasbourg) we have a large quantity (> 900) of astronomical catalogues, most of these being made of one or more tables. Descriptions of all these tables are being homogeneized according to standards (document referenced below) also adopted by the ADC . One of the important features of this standard is the facility of converting any of these documented tables into FITS (ascii table extension), and presently over 500 catalogues have such descriptions. One of the key issues in the interpretaion of tabular data is the understanding of the units in which the data are expressed. The rules adopted in this standard for specifying the units are more rigid than the OGIP definitions, and since hundreds of tables using these conventions already exist and are in use, we feel it could be worthwhile to let the FITS community aware of these conventions for discussion. The complete definitions concerning units are detailed in the document; they can be resumed by the 4 rules: - - the symbol of any unit is a single word (no embedded space) - - a numeric factor can only precede the symbols, e.g. 0.01arcsec/yr not arcsec/(100yr) - - operators are only the dot (.) for the multiplication, the slash (/) for the division, and integer powers (+ or -). with classical precedence rules. Examples: km/s or km.s-1 W/m2/Hz or W.m-2.Hz-1 - - the list includes about 50 basic unit symbols: SI, IAU extensions, atomic physics extensions (sorry, CGS units are excluded!) Despite of the large number of tables examined, we never found any necessity to introduce non-integer powers or functions of units like e.g. log(K) to express "logarithm of Kelvin" --- and in fact log(K) is rather a scale, not a physical unit! Besides the question of units, the document also addresses other conventions, like a simple way of designating related columns (typically a value and its related error) Any comment, suggestion, etc would be appreciated ! Francois Ochsenbein / CDS Strasbourg, France ================================================================================ Document on the "Astronomical Catalogues at CDS: Adopted Standards" is available on URL ftp:://cdsarc.u-strasbg.fr/pub/cats/doc.ps (TeX and dvi versions also available) Hundreds of asatronomical catalogues at URL http:://cdsweb.u-strasbg.fr/Cats.html ================================================================================ _/_/_/_/_/_/ . . . Centre de Donnees astronomiques de _/ Strasbourg _/ http://cdsweb.u-strasbg.fr/CDS.html _/ _/_/ _/_/_/ _/ _/ _/ _/ Francois Ochsenbein _/_/_/_/ _/ _/_/_/_/ Internet: francois at simbad.u-strasbg.fr _/ _/ _/ _/ Phone: +33 88 35 84 11 _/_/ _/_/_/ _/ Fax: +33 88 25 01 60 _/ Post: Observatoire Astronomique _/ 11, rue de l'Universite . . . _/_/_/_/_/_/_/ 67000 STRASBOURG, France ================================================================================ ------- end ------- From fitsbits-request Mon Sep 19 16:50:45 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1001" "" "19" "September" "1994" "17:21:50" "GMT" "Andy J Kozubal" "kozubal at sst10b.lanl.gov" nil "21" "Conversion between OODB and FITS formats" "^From:" nil nil "9" nil nil (number " " mark " Andy J Kozubal Sep 19 21/1001 " thread-indent "\"Conversion between OODB and FITS formats\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA06818; Mon, 19 Sep 94 16:50:45 EDT Return-Path: Message-Id: <35khbe$2cs at newshost.lanl.gov> Organization: Los Alamos National Lab Path: saips.cv.nrao.edu!hearst.acc.Virginia.EDU!concert!gatech!ncar!newshost.lanl.gov!sst10b!kozubal From: kozubal at sst10b.lanl.gov (Andy J Kozubal) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Conversion between OODB and FITS formats Date: 19 Sep 1994 17:21:50 GMT Does anyone have any experience using an object-oriented database (OODB) to store astrophysics data? Are there any programs or functions available to convert between OODB formats and FITS format? I just started on a project that will use FITS to store data from X-ray cameras. We will eventually have 100's of GBytes that will be on-line in hundreds of files. Maintaining these files seems like a formidable task, so I'm looking for some tools to help keep things manageable. One possibility is to use the organizing capability of an OODB. I have never used FITS before, and I am still a novice to OODBs (I do have lots of experience with relational DB systems). Thanks, ----------------------------------------------------------------------- Andy Kozubal | Mail Stop D440 Phone: (505) 665-7724 | Los Alamos National Laboratory E-mail: AKozubal at lanl.gov | Los Alamos, New Mexico 87545 ----------------------------------------------------------------------- From fitsbits-request Thu Sep 22 16:50:51 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["755" "" "22" "September" "1994" "19:40:50" "GMT" "William Thompson" "thompson at orpheus.gsfc.nasa.gov" nil "18" "Modified Julian Day" "^From:" nil nil "9" nil nil (number " " mark " William Thompson Sep 22 18/755 " thread-indent "\"Modified Julian Day\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA14935; Thu, 22 Sep 94 16:50:51 EDT Return-Path: Message-Id: <35smk2$j2m at paperboy.gsfc.nasa.gov> Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA Path: saips.cv.nrao.edu!hearst.acc.Virginia.EDU!darwin.sura.net!tulane!ames!newsfeed.gsfc.nasa.gov!orpheus.gsfc.nasa.gov!thompson From: thompson at orpheus.gsfc.nasa.gov (William Thompson) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Modified Julian Day Date: 22 Sep 1994 19:40:50 GMT I've been hearing lately that the IAU either has, or is about to, "outlaw" the use of Modified Julian Day numbers. Can anyone shed some light on this? The SoHO/CDS software library contains IDL software to convert between various time formats (URL ftp://idlastro.gsfc.nasa.gov/contrib/thompson/time). The so-called "internal" uses MJD numbers to store the date information. This is convenient, because one can easily convert this into various civilian date formats, using equations from the Astronomical Almanac Supplement. Is there such a ban in place now, or is it simply being considered? Would it apply to internal formats within software, or only to external use such as publications and (e.g. FITS) data files? Thank you, William Thompson From fitsbits-request Thu Sep 22 17:31:16 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2922" "Thu" "22" "September" "1994" "21:31:00" "GMT" "Don Wells" "dwells at nrao.edu" nil "76" "Announcement -- WCS BOF at ADASS'94" "^From:" nil nil "9" nil nil (number " " mark " Don Wells Sep 22 76/2922 " thread-indent "\"Announcement -- WCS BOF at ADASS'94\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA15059; Thu, 22 Sep 94 17:31:16 EDT Return-Path: Message-Id: Organization: nrao Path: saips.cv.nrao.edu!news.cv.nrao.edu!dwells From: dwells at nrao.edu (Don Wells) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Announcement -- WCS BOF at ADASS'94 Date: Thu, 22 Sep 1994 21:31:00 GMT Announcment: World Coordinate Systems [WCS] Session to be held at the ADASS'94 FITS BOF 19:00 Monday 26 September There will be a FITS BOF [Birds-Of-a-Feather] session on Monday evening at ADASS'94 (Omni Inner Harbor Hotel, Baltimore, Maryland). The first item on the agenda will be World Coordinate Systems [WCS]. The WCS portion of the BOF will last no more than one hour, with at least half an hour reserved for other FITS topics. The first speaker on WCS will be Eric Greisen, who will introduce the subject by giving an overview of and answering questions about the current draft proposal, which can be fetched from: ftp://fits.cv.nrao.edu/fits/documents/wcs/wcs.all.ps.Z All astronomical computing people who are interested in the problem of associating celestial coordinate information with astronomical digital imagery should attend the first hour of this FITS BOF session. The second WCS speaker will be Doug Tody, who will discuss the IRAF WCS implementation, and will describe the AIPS<-->IRAF WCS interoperability tests which he and Eric performed in August. The remainder of the hour will be available for reports of other WCS implementations, answering technical questions, etc. Anyone who would like to give brief informal discussion of WCS matters should contact me so that time can be reserved. If there are people who will not be attending ADASS'94, but who wish to contribute to this session, I will be pleased to receive Email from them and will read or summarize their messages during the session. -=- Sample Imagery -=- I have created a directory for samples of FITS files which have WCS information in their headers: ftp://fits.cv.nrao.edu/fits/sampledata/wcs/ The initial contents of this directory are: 311040 Sep 22 16:44 m82opt.fits 11726 Sep 22 16:52 m82opt.lst 305280 Sep 22 16:45 m82rad.fits 5553 Sep 22 16:54 m82rad.lst 538560 Sep 22 16:44 ngc1316o.fits 6891 Sep 22 16:56 ngc1316o.lst 538560 Sep 22 16:44 ngc1316r.fits 7538 Sep 22 16:57 ngc1316r.lst The files in this directory use FITS syntactic and semantic conventions which are upwardly compatible with those described in the draft document ftp://fits.cv.nrao.edu/fits/documents/wcs/wcs.all.ps.Z. The *.lst files are listings of the FITS headers. The pairs of radio and optical imagery have been re-gridded so that they are suitable for 'blink' comparison. One pair uses the 'ARC' projection, the other uses 'SIN'. Both IRAF and AIPS can interpret the coordinate information in these headers. I will be delighted to receive additional examples of WCS usage. -- 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 fitsbits-request Fri Sep 23 16:32:59 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["573" "Fri" "23" "September" "1994" "14:38:01" "" "Andrew J. P. Maclean" "a.maclean at uws.edu.au" nil "14" "AIPS++" "^From:" nil nil "9" nil nil (number " " mark " Andrew J. P. Macl Sep 23 14/573 " thread-indent "\"AIPS++\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA18068; Fri, 23 Sep 94 16:32:59 EDT Return-Path: Message-Id: Organization: University of Western Sydney Path: saips.cv.nrao.edu!hearst.acc.Virginia.EDU!concert!gatech!udel!MathWorks.Com!zombie.ncsc.mil!gmi!msuinfo!harbinger.cc.monash.edu.au!news.cs.su.oz.au!metro!ob1.uws.edu.au!uws.edu.au!a.maclean From: a.maclean at uws.edu.au (Andrew J. P. Maclean) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: AIPS++ Date: Fri, 23 Sep 1994 14:38:01 Does anyone know where I can locate the AIPS++ library for manipulating FITS files? +----------------------------------+-------------------------------+ | Andrew J. P. Maclean | | | University Planner | | | University of Western Sydney | Ph: +61 (02) 678 7848 | | PO Box 1000, St Marys, NSW 2760 | Fax: +61 (02) 678 7804 | | Australia | e-mail: a.maclean at uws.edu.au | +----------------------------------+-------------------------------+ From fitsbits-request Sun Sep 25 20:20:07 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["492" "Mon" "19" "September" "1994" "20:19:00" "+0200" "Georg Dittie" "G.DITTIE at CL-HH.comlink.de" nil "15" "Suitable way to detect three color images in FITS ?" "^From:" nil nil "9" nil nil (number " " mark " Georg Dittie Sep 19 15/492 " thread-indent "\"Suitable way to detect three color images in FITS ?\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA25075; Sun, 25 Sep 94 20:20:07 EDT Return-Path: Message-Id: <5XAtM72p3zB at p-gdi.cl-hh.comlink.de> Path: saips.cv.nrao.edu!hearst.acc.Virginia.EDU!concert!gatech!howland.reston.ans.net!xlink.net!news.ppp.de!news.Hanse.DE!lutzifer.hanse.de!news.comlink.de!hades.comlink.de!cl-hh.comlink.de!G.DITTIE From: G.DITTIE at CL-HH.comlink.de (Georg Dittie) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Suitable way to detect three color images in FITS ? Date: Mon, 19 Sep 1994 20:19:00 +0200 Hi to all experienced... Is there a suitable way to detect automatically if a three dimensional FITS image is a color image and not a image series ? One way could be to look at the unit specification of dimension three (=3 color channels) or dimension one (RGB-Triple) or an identification with the keyword COMMENT. Which way is used most often ? Thank you for a short hint. I couldn t find anything about this matter in the official FITS-Doku. Georg. ## CrossPoint v3.02 R ## From fitsbits-request Tue Sep 27 17:31:37 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1661" "Tue" "27" "September" "1994" "21:30:21" "GMT" "Don Wells" "dwells at nrao.edu" nil "36" "Re: Modified Julian Day" "^From:" nil nil "9" nil nil (number " " mark " Don Wells Sep 27 36/1661 " thread-indent "\"Re: Modified Julian Day\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA29715; Tue, 27 Sep 94 17:31:37 EDT Return-Path: Message-Id: Organization: nrao Path: saips.cv.nrao.edu!news.cv.nrao.edu!dwells References: <35smk2$j2m at paperboy.gsfc.nasa.gov> From: dwells at nrao.edu (Don Wells) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Re: Modified Julian Day Date: Tue, 27 Sep 1994 21:30:21 GMT [this followup was posted to sci.astro.research:] From: aty at ucssun1.sdsu.edu (young a t) Newsgroups: sci.astro.research Subject: Re: Modified Julian Day Date: 26 Sep 1994 09:35:45 -0500 Organization: San Diego State University In article <35t02e$5v at pecos.msfc.nasa.gov>, William Thompson wrote: > >I've been hearing lately that the IAU either has, or is about to, "outlaw" the >use of Modified Julian Day numbers. Can anyone shed some light on this? At the recent General Assembly in The Hague, the IAU adopted a resolution that effectively cancelled an earlier one that recommended the use of MJD. The basic problem was that the previously adopted MJD (which was itself an attempt to clear up the confusion among several modifications of the full Julian Day count then in use) had led to further confusion. The long and the short of it seems to be that one should stick to the full JD number, instead of leaving off 2,400,000 or 2,400,000.5 or any other quantity. "Modified" Julian Day has turned out to be so prone to confusion and error that we are all better off to use plain vanilla JD. If you absolutely *must* truncate the first 2 digits, explain that what you are using is JD - 2,400,000 and *don't* try to call it MJD. -- A.T.Young aty at mintaka.sdsu.edu Astronomy Department San Diego State University San Diego CA 92182-0540 -- Donald C. Wells Associate Scientist dwells at nrao.edu http://fits.cv.nrao.edu/~dwells National Radio Astronomy Observatory +1-804-296-0277 520 Edgemont Road, Charlottesville, Virginia 22903-2475 USA From fitsbits-request Thu Sep 29 17:49:44 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2997" "Thu" "29" "September" "1994" "21:48:46" "GMT" "Don Wells" "dwells at nrao.edu" nil "64" "Re: Modified Julian Day" "^From:" nil nil "9" nil nil (number " " mark " Don Wells Sep 29 64/2997 " thread-indent "\"Re: Modified Julian Day\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA05767; Thu, 29 Sep 94 17:49:44 EDT Return-Path: Message-Id: Organization: nrao Path: saips.cv.nrao.edu!news.cv.nrao.edu!dwells References: <35smk2$j2m at paperboy.gsfc.nasa.gov> From: dwells at nrao.edu (Don Wells) Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Subject: Re: Modified Julian Day Date: Thu, 29 Sep 1994 21:48:46 GMT [Here is yet another of Andy Young's followups in sci.astro.research -Don] From: aty at ucssun1.sdsu.edu (young a t) Newsgroups: sci.astro.research Subject: Re: Modified Julian Day Date: 28 Sep 1994 09:52:11 -0500 Organization: San Diego State University Message-ID: <36bvur$2p6 at pecos.msfc.nasa.gov> References: <35t02e$5v at pecos.msfc.nasa.gov> <366m81$1oo at pecos.msfc.nasa.gov> <367ekq$1vr at pecos.msfc.nasa.gov> In article <367ekq$1vr at pecos.msfc.nasa.gov>, Joe Cain wrote: >In article <366m81$1oo at pecos.msfc.nasa.gov> aty at ucssun1.sdsu.edu writes: >>In article <35t02e$5v at pecos.msfc.nasa.gov>, >>William Thompson wrote: ... >We have been using MJD = JD - 2400000.5 for about 30 years in >geophysics and don't see any reason to change so long as the >definition is clear. We picked it up from SAO when first starting to >put times on data and found that one CDC word in binary was good to a >millisecond. Now we have to use some other means to store in the >shorter words of "modern" platforms. It is better than the "Julian >Day" generally used by NASA orbital mechanics which only means the day ^^^^^^^^^^^^^^^^^^^^^^ (and UNIX programmers...) >of that year. > How about instead just defining MJD as such and keep it as a useful >concept for many purposes? Most people don't like the idea of a day That was what the IAU tried some years ago. The main problem was caused by the half day, because the variable-star folks had been using JD - 2400000 (no half day) for a long time. The result was that people started calling (JD - 2400000) "MJD" and thus not following the IAU-approved definition. This year, the IAU gave it up as a bad job; not enough users have the necessary discipline to keep to the definition. >... Most people don't like the idea of a day >starting at noon except for astronomers .... Well, most people don't like time tied to Greenwich unless they live near England. The half day was for the convenience of European astronomers back in the last century; I'm not sure when that half-day offset from Greenwich time was introduced. It was officially abandoned by astronomers in 1925, when we went from GMAT to UT as the standard. But, to avoid confusion, the JD count continued to change at Greenwich Mean Noon. You are, of course, welcome to continue using MJD *if* you keep your readers informed of what you mean by it. It's just no longer approved by the IAU as an astronomical standard. Like Prohibition, it looked like a good idea at one time, but did not work out well in practice.... -- A.T.Young aty at mintaka.sdsu.edu Astronomy Department San Diego State University San Diego CA 92182-0540 -- 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 fitsbits-request Fri Sep 30 09:02:51 1994 Status: RO X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5124" "Fri" "30" "September" "1994" "09:02:46" "-0400" "Arnold Rots" "arots at xebec.gsfc.nasa.gov" nil "106" "Re: Modified Julian Day" "^From:" nil nil "9" nil nil (number " " mark " Arnold Rots Sep 30 106/5124 " thread-indent "\"Re: Modified Julian Day\"\n") nil] nil) Received: by fits.cv.nrao.edu (4.1/DDN-DLB/1.5) id AA07826; Fri, 30 Sep 94 09:02:51 EDT Return-Path: Message-Id: <199409301302.JAA10026 at xebec.gsfc.nasa.gov> From: Arnold Rots Sender: fitsbits-request at fits.CV.NRAO.EDU To: fitsbits at fits.CV.NRAO.EDU Cc: arots at xebec.gsfc.nasa.gov Subject: Re: Modified Julian Day Date: Fri, 30 Sep 1994 09:02:46 -0400 > [Here is yet another of Andy Young's followups in sci.astro.research -Don] > From: aty at ucssun1.sdsu.edu (young a t) > Newsgroups: sci.astro.research > Subject: Re: Modified Julian Day > Date: 28 Sep 1994 09:52:11 -0500 > Organization: San Diego State University > Message-ID: <36bvur$2p6 at pecos.msfc.nasa.gov> > References: <35t02e$5v at pecos.msfc.nasa.gov> <366m81$1oo at pecos.msfc.nasa.gov> <367ekq$1vr at pecos.msfc.nasa.gov> > In article <367ekq$1vr at pecos.msfc.nasa.gov>, > Joe Cain wrote: > >In article <366m81$1oo at pecos.msfc.nasa.gov> aty at ucssun1.sdsu.edu writes: > >>In article <35t02e$5v at pecos.msfc.nasa.gov>, > >>William Thompson wrote: > ... > >We have been using MJD = JD - 2400000.5 for about 30 years in > >geophysics and don't see any reason to change so long as the > >definition is clear. We picked it up from SAO when first starting to > >put times on data and found that one CDC word in binary was good to a > >millisecond. Now we have to use some other means to store in the > >shorter words of "modern" platforms. It is better than the "Julian > >Day" generally used by NASA orbital mechanics which only means the day > ^^^^^^^^^^^^^^^^^^^^^^ > (and UNIX programmers...) > >of that year. > > How about instead just defining MJD as such and keep it as a useful > >concept for many purposes? Most people don't like the idea of a day > That was what the IAU tried some years ago. The main problem was caused > by the half day, because the variable-star folks had been using JD - 2400000 > (no half day) for a long time. The result was that people started calling > (JD - 2400000) "MJD" and thus not following the IAU-approved definition. > This year, the IAU gave it up as a bad job; not enough users have the necessary > discipline to keep to the definition. It looks very much like the tail wagging the dog. To me it appears as though a tiny segment of the community couldn't muster the discipline to call their deviant definition something else and, after having caused confusion in their own circles (there are variable star people who do use the proper definition of MJD), possibly out of spite, force everbody to abandon a useful concept. This decision to recant is even worse, since most of the community is not going to change what they have been doing for years, acting as if it still is an IAU-blessed unit, while in reality it isn't (speaking of confusion!). There are too many FITS files out with MJD, there is too much software that uses it. The variable star folks will have to face reality and acknowledge that even an IAU decision can't keep the community from using the former IAU-condoned definition of MJD. > >... Most people don't like the idea of a day > >starting at noon except for astronomers .... > Well, most people don't like time tied to Greenwich unless they live near > England. The half day was for the convenience of European astronomers > back in the last century; I'm not sure when that half-day offset from > Greenwich time was introduced. It was officially abandoned by astronomers > in 1925, when we went from GMAT to UT as the standard. But, to avoid > confusion, the JD count continued to change at Greenwich Mean Noon. I rather suspect that the half day offset originated from nautical practice to start the day at noon: that was the moment in the day that all important things happened, with noon sightings of the sun and taking the nautical almanac from the shelf - determining the elevation of the sun at midnight is too problematic. > You are, of course, welcome to continue using MJD *if* you keep your > readers informed of what you mean by it. It's just no longer approved > by the IAU as an astronomical standard. Like Prohibition, it looked > like a good idea at one time, but did not work out well in practice.... Unlike prohibition, it _was_ a good idea ... I'm sure this was pretty much a storm in a teacup. FITS files will continue to carry MJD - perhaps with an extra comment - and most astronomical software will continue to use it. What may need to be stressed, though, is that using MJD (or JD, for that matter) for defining a moment in absolute time requires not only an MJD value that includes a fractional part, but also an indication what time system is being used. The Julian Day is not tied to any particular time system (UTC, TAI, TT, ...), it only provides a formalism for counting calendar days within such a time system. For instance, the epoch 1994.0 (UTC) (January 1, 1994 at 00:00:00 UTC, or MJD=49352.0 (UTC)), is at MJD=49352.000696574074 (TT). Very seldom does one see a time system identified when MJD is given. > -- > A.T.Young aty at mintaka.sdsu.edu > Astronomy Department > San Diego State University > San Diego CA 92182-0540 > -- > 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 - Arnold Rots