[Green Jay] [Thick-billed Parrot] [Golden-cheeked Warbler] [Mexican Jay]

[Arctic Tern] Eric W. Greisen [Eric W. Greisen] [Tufted Puffin]

[Northern Potou] [Iiwi] [Red-billed Tropicbird] [Northern Hawk Owl] [Tengmalm's Boreal Owl]

[Bay-breasted Warbler] [Greater Prairie-Chicken] [Chukar] [Black and Grey-crowned Rosy Finch] [Green Honeycreeper]

[Broad-billed Sandpiper] [Red Phalarope] [Ocellated Turkey] [Burchell's Common Zebra] [White Rhinoceros]

[Asian Elephant] [Bengal Tiger] [Capybara] [Giant Anteater] [Marine Iguana]



I am a Scientist at the National Radio Astronomy Observatory. I was stationed at NRAO's headquarters in Charlottesville, Virginia for about 28 years. I am now fully transferred to NRAO's Array Operations Center in Socorro, NM. My main job at the present time is to develop and maintain the software package known as AIPS. I am also involved in FITS matters especially in the development of new standards for representing coordinate information. I even find time for a bit of life. A plain-text version of my curriculum vitae is available.

The big news around Socorro is that the EVLA is here. You may download the latest version, dated April 2014, of the CookBook Appendix E on special considerations for ELA data processing in AIPS. It is also available in pdf format. I was one of several people who reduced a set of data from the WIDAR-0 version of the new correlator. The observations were on the hot core at the center of Orion at K band. Two hours were spent one day to cover one GHz with 8192 channels each 0.125 MHz wide. Two hours were spent the next day, covering a slightly overlapping 1 GHz, and 1 hours was spent on a third day doing another 1 GHz. Karl Menten provided line identifications. The full spectrum I obtained with AIPS is shown in poster which also shows blown-up spectra and hue-intensity images of some of the molecular lines. Only 12 antennas were used for this experiment. The full EVLA when it it is up and running will be absolutely amazing. And some day the software will catch up.

My pages on these matters include the following items:

I have published a new paper entitled "Aperture Synthesis Observations of the Nearby Spiral NGC~6503: Modeling the Thin and Thick HI Disks". While I reduced the data and did a substantial amount of the analysis, the real science and improved scientific writing style are the contributions of my co-author Kristine Spekkens. The published paper is available from the Astronomical Journal or from a local pdf (3 Mbyte) copy. The submitted drafts, following positive and helpful comments from a referee, are available in PostScript (23 Mbytes) and pdf (7 Mbytes) formats.

The FITS Interferometry Data Interchange Convention (formerly Format) is being re-examined as an IAU-acknowledged convention. This convention was documented by Chris Flatters in AIPS Memo 102 which, unfortunately, was not accompanied by an editable text version. Therefore, I have had to re-type the document. While doing so, I updated some matters, corrected minor wording issues, and added 5 new sections for 5 new tables, 3 of which are actually in use. Interested parties should review my AIPS Memo 114 in Postscript or in pdf. I have attempted to highlight the changed parts in red in this draft, plus changes made after submission to the IAU Committee in blue. The current draft is dated August 2011 and includes a revised MODEL_COMPS table and comments from Lorant Sjowerman, Bill Cotton, and others. A memo detailing the AIPS FITS format tables and data has been written as AIPS Memo 117 in PostScript and in pdf. Please e-mail me with comments on these memos.

I have worked on several publications in 2002. I gave an invited talk (gzipped 2807999 bytes or uncompressed 3895373 bytes) on Wide-field Imaging in Classic AIPS at the International URSI meeting in Maastricht Holland in August. It was accompanied by a short paper (665829 bytes). I have had two chapters published in the book Information Handling in Astronomy - Historical Vistas, edited by Andre Heck (Kluwer, Astrophysics and Space Science Library, 285). One was a chapter on AIPS (compressed 2295579 bytes or uncompressed 9459219 bytes). The other was a chapter on FITS (compressed 785182 bytes or uncompressed 2948982 bytes). Both of these were educational experiences, especially when I had to review the scientific achievements of the VLA and VLBA. My old lecture on the early history of AIPS from the Barryfest is also available.

I have worked with Mark Calabretta off and on since 1992 on a detailed proposal for representing world coordinates in FITS. There will now be four papers: I on general matters, II on ideal celestial coordinates, III on ideal spectral coordinates, and IV on distortion corrections used to convert real instruments into these ideal coordinates. Papers I and II have been published by Astronomy & Astrophysics and accepted into the FITS standard for general use by the IAU. Paper III has been published in Astronomy & Astrophysics and has been endorsed by the IAU FITS working group. Paper IV is being developed. The A&A versions of I, II, and III are available below.

  1. Representations of world coordinates in FITS by Greisen and Calabretta (246829 bytes pdf file from A&A) A&A, Volume 395, pages 1061-1075
  2. Representations of celestial coordinates in FITS by Calabretta and Greisen (1279957 bytes pdf file from A&A), A&A, Volume 395, pages 1077-1122
  3. Representations of spectral coordinates in FITS by Greisen, Calabretta, Valdes, and Allen (gzipped 204653 bytes) or unzipped (551653 bytes) or pdf (769502 bytes) astro-ph/0507293, A&A, Volume 446, pages 747-771

Papers I and II were submitted to the North American FITS Committee of the AAS and were accepted by a vote of 15-0 with 3 non-voting. The Japanese and European FITS Committees have also approved them unanimously. The FITS Working Group of the IAU then accepted them on December 18, 2002 by a vote of 14-0 with 2 non-voting. Paper III has also been approved by the regional and IAU FITS Committees and published. Paper IV has been worked on, but has taken a back seat while we polish Papers I, II, and III.

The text of a proposal by Steve Allen and Doug Mink for "Concatenation of FITS World Coordinate Systems" is also now available for general review. This was raised on the fitswcs mailing list on 2002/01/01 and following and ideally would have been included in Paper I. However, we felt that the FITS community had not had adequate time to review it, yet we didn't want to delay Paper I further. Thus it is presented as a separate proposal.

General comments on paper IV may be sent to fitswcs@nrao.edu which is a general mail exploder for discussion of such matters. Typographical corrections are best just sent to the authors.

Eric W. Greisen
egreisen@nrao.edu