Astronomical Image Processing System


Apple Mac news

Apple has released a new line of Mac computers based on Apple Silicon rather than the Intel cpus that they have been using. NRAO has provided AIPS with a Mac Mini with the new M1 chip and with gfortran 11. I have spent the last several months upgrading AIPS software to the strict demands of this latest compiler. We are forced to use this one since it is the only one that understands Apple's ARM architecture. This new MACARM AIPS architecture has been released and may be installed as a binary release. The really good news is that this relatively inexpensive computer reached an AIPSMark of 1290, which is a new record by almost a factor of 2! The Y2K Large test ran in only 31 seconds real time. The same computer running the MACINT load modules under the Rosetta system had an AIPSMark of 1000.

Current Mac OS versions no longer support 32-bit load modules. Since we were under the impression that the Intel compiler we had used for the MACINT architecture produced 32-bit code, we switched to using gfortran 6.3. This caused no degradation in performance and is easier to maintain. You will need to invoke the bash script to link up the 3 new gfortran run-time libraries provided with AIPS. Please contact the science helpdesk or if there are problems. Note that the 31DEC18 and earlier versions of AIPS may not run on Mac OS 10.15 and later.

EOP web site has moved and changed

The names of the TEC files have changed so that names after day 219 of 2023 are different in form than those before day 220 of 2023. The TECR procedures in VLBAUTIL and VLAPROCS have been changed in versions 31DEC22 and 31DEC23. Run the MNJ ("Midnight Job") which is $HOME/do_daily.hostname to update your version. Older AIPS versions have not been changed.

The location of the EOP and TEC files used by AIPS has changed and a new method of downloading them is required (using curl). The VLBA and VLA procedures that download these files have been changed to the new requirements in 31DEC19 and later versions. You will need to be running one of these versions to do the automatic downloading.

A new web location for the Goddard EOP data files has appeared. Furthermore, anonymous ftp is no longer allowed. A special "curl" command does, however, work. The procedures VLBAEOPS and VLBATECR in VLBAUTIL has been updated in 31DEC18 and later versions. The old web site at is gone. We thank the folks at Goddard for providing these files through a back channel to support NRAO's correlators during the outage and for creating this new web location and access method.

Solaris binary support has ended

The support for the Solaris operating system in Socorro has been terminated due to the failure of shire in a power outage. The binary installations of Solaris (and of Mac PPC) are not provided in the 31DEC18 and later releases. They are available in the 31DEC17 and earlier releases. If you have this sort of computer, you may still take AIPS in text form and compile it locally. The code was corrected a while back to survive modern Fortran compilers and the Solaris scripts for compiling AIPS have been used for a great many years.

NRAO helpdesk

NRAO has instituted a "helpdesk" system similar to those at other astronomical institutions. AIPS will participate in this effort which is intended to avoid having problems fall between the cracks. The helpdesk is accessed via Note that the help site will forward you to my.nrao to create a login if you do not already have one and the my.nrao site will then offer a tab to reach the helpdesk. The system for the AIPS "department" will make use of the list manager system that we have used for years. Thus, unlike the rest of the NRAO helpdesk, messages to the AIPS portion will be made public in the daip archive. This archive is accessible via the web and is well known to Google among other things. Please switch to the new helpdesk to allow more systematic handling of your AIPS queries and bug reports.

Scheduled Releases

The development version 31DEC24 is available, the previous development version 31DEC23 is "slushy" (frequent updates in December, then only patches in 2024), and the old frozen version 31DEC22 may not be available for installation much longer. (A MNJ on 31DEC22, if it has not been run since December 2023, might still be useful.) The new rsync (cvs for text installations) forms of the Midnight Job have been very easy to use and effective in keeping numerous sites up to date. In 2024, the MNJ will work sometimes on 31DEC23 if there has been a released patch. The 31DEC24 and 31DEC23 releases are also available as binary installations (and MNJs). The 31DEC16 and later MNJs no longer require cvs for binary installations, just rsync. 31DEC24 no loger requires cvs even for text installations (other than the master machines in Socorro).

TeK and message server problems

Users have encountered problems getting the TeK and message servers to work in binary installations. These servers are programs which run in an xterm and that xterm must come up with some knowledge of AIPS libraries. This requires users to modify their login scripts (e.g. .cshrc file for c shell, .bashrc file for bash). See for details.

Linux compiler troubles

Older versions of the gnu Fortran compiler do not work with AIPS. Versions 4.4.7 and beyond do seem to work after some cleaning up of the AIPS code. Gnu Fortran versions 7 and 8 required revision of the handling of the AIPS pseudo array processor code. The latter used to use a COMMON for its dynamic memory base, which did not compile well on gfortran versions > 6. Using a variable passed down from above instead works well. The Mac (Intel) and Linux (64-bit) binary releases use gfortran version 6.4. The new Mac ARM (M1) cpu chip required the use of gfortran 11. That compiler is very strict about apparent inconsistencies and so forced a lot of changes to code that was in fact working correctly.


Also, see the Users' FAQ: answers to Frequently Asked Questions, the AIPS Managers' FAQ: answers to AIPS Managers (and installers) Frequent Questions; and our page on who is in the AIPS group. The AIPS Manager FAQ page is especially helpful if you are having trouble getting the AIPS TV to run properly or are encountering other general difficulties or wish to configure new machines and disks in your AIPS environment.


  • 31DEC24 is the new primary development version of AIPS. It is ready for installation.
  • 31DEC23 is the newly "slushy" version of AIPS. It is ready for installation. The final report on 31DEC23 is available as 31DEC23 AIPSLetter dated 31 December 2023 (PS, 1017389 bytes). It is also available gzipped, (465648 bytes) and PDF, (188112 bytes). The 6-month progress report on 31DEC23 is available as 31DEC23 AIPSLetter dated 30 June 2023 (PS, 1018605 bytes). It is also available gzipped (467038 bytes) and PDF, (182929 bytes).

    There are files used by the MNJ ("Midnight Job") which may not transfer properly with the MNJ for sites that compile the AIPS code locally. They are named AIPSUPD, UPDCONFIG, UPDERROR, and UPDPSYNC. Copies of these files are in the same data areas as the 31DEC23.tar.gz for download via the web or via ftp. Put them in the $AIPS_ROOT/31DEC23/$ARCH/UPDATE directory.
  • 31DEC22 is the newly obsolete version of AIPS. It is ready for installation. The final report on 31DEC22 is available as 31DEC22 AIPSLetter dated 31 December 2022 (PS, 1041563 bytes). It is also available gzipped, (498836 bytes) and PDF, (183318 bytes). The 6-month progress report on 31DEC22 is available as 31DEC22 AIPSLetter dated 30 June 2022 (PS, 1082649 bytes). It is also available gzipped (498836 bytes) and PDF, (183318 bytes).
  • 31DEC21 is the newly obsolete version of AIPS. It is available for installation. The final report on 31DEC21 is available as 31DEC21 AIPSLetter dated 31 December 2021 (PS, 1015726 bytes). It is also available gzipped, (462833 bytes) and PDF, (189631 bytes). The 6-month progress report on 31DEC21 is available as 31DEC21 AIPSLetter dated 30 June 2021 (PS, 946615 bytes). It is also available gzipped (444817 bytes) and PDF, (152823 bytes).
  • 31DEC20 is another obsolete version of AIPS. It is still available for installation for a limited time. The final report on 31DEC20 is available as 31DEC20 AIPSLetter dated 31 December 2020 (PS, 2700146 bytes). It is also available gzipped, (691630 bytes) and PDF, (481271 bytes). The 6-month progress report on 31DEC20 is available as 31DEC20 AIPSLetter dated 30 June 2020 (PS, 1010321 bytes). It is also available gzipped (463109 bytes) and PDF, (186199 bytes).
  • 31DEC19 is the now obsolete version of AIPS. It is no longer available for installation. The final report on 31DEC19 is available as 31DEC19 AIPSLetter dated 31 December 2019 (PS, 864697 bytes). It is also available gzipped, (433388 bytes) and PDF, (187651 bytes). The 6-month progress report on 31DEC19 is available as 31DEC19 AIPSLetter dated 30 June 2018 (PS, 869314 bytes). It is also available gzipped, (402257 bytes) and PDF, (141532 bytes).
  • 31DEC18 is the now obsolete version of AIPS. It is available for installation for a while and is the last Intel-compiled version for Macs. The final report on 31DEC18 is available as 31DEC18 AIPSLetter dated 31 December 2018 (PS, 8022909 bytes). It is also available gzipped, (1008277 bytes) and PDF, (244403 bytes). The 6-month progress report on 31DEC18 is available as 31DEC18 AIPSLetter dated 30 June 2018 (PS, 867221 bytes). It is also available gzipped, (401469 bytes) and PDF, (140662 bytes).
  • 31DEC17 is the no longer available for installation. The final report on 31DEC17 is available as 31DEC17 AIPSLetter dated 31 December 2017 (PS, 904027 bytes). It is also available gzipped, (420144 bytes) and PDF, (159226 bytes). The 6-month progress report on 31DEC17 is available as 31DEC17 AIPSLetter dated 30 June 2017 (PS, 902569 bytes). It is also available gzipped, (419491 bytes) and PDF, (159212 bytes).
  • 31DEC06 and later releases contain a port to the MacIntosh OS/X system running on Intel cpus. This includes a full binary installation produced with the gfortran compiler. The iMac which was originally used for the Mac Intel ort has been replaced with a more modern Mac mini.
  • Since the end of January 2009, Linux systems running on 64-bit hardware with 64-bit operating systems have the choice of using LNX64 rather than LINUX as their AIPS architecture. The binary version for LNX64 is compiled with a a 64-bit gfortran compiler and runs somewhat faster than the LINUX version run on the same machines.
  • From September 1, 2005 through October, 2017, the binary versions for Linux are compiled with the Intel compiler version 9.0. Those load modules developed oddities on newer computers, especially in Europe. We have switched to gfortran 6.3 which has performance about equal to the Intel load modules (on those computers that ran them properly).
  • If you own a MacIntosh OS X computer, you may now run AIPS. All available AIPS versions contain the MACINT port and 31DEC22 contains code for the new ARM (M1) cpu chip (MACARM). The Mac version is now compiled with gfortran which allows load modules to be built to support older Mac OS versions back to 11.1. Read also the rather obsolete Mac installation instructions which are supplements to the A Guide to the Install Wizard instructions.
  • When you get 31DEC22 or 31DEC21, use the new install wizard; we have a good on-line guide that will help you through it. Read it!
  • The 15OCT99, 31DEC00, 31DEC01, 31DEC02, 31DEC03 31DEC04 31DEC05 31DEC06 31DEC07 31DEC08 31DEC09 31DEC10 31DEC11 31DEC12 31DEC13 31DEC14 31DEC15 31DEC16 31DEC17 releases of AIPS are no longer available; the number of bug fixes and differences between them and the current version have become too great. The continued significant demand for a frozen, even if obsolete, version was the main reason we decided to resume regular releases.


Two extensive tutorials on VLBI data reduction in AIPS have been prepared, complete with data sets, introductory material about AIPS, and detailed instructions. They are simple VLBA project including self-calibration and spectral-line VLBA project plus astrometry. Users new to, or rusty in, VLBI data reduction are encouraged to try these tutorials. Appendix C and Chapter 9 of the AIPS CookBook are also recommended.

The VLBA pipeline procedure has been improved and may be useful to you. In addition, a pipeline for reducing VLBA data from secondary phase-stopping positions has been written. See VLBARUN information for details.


There are sometimes considerations which users of older versions of AIPS must take into account due to changes in the latest version. In addition, there are sometimes bugs introduced into the latest version which then get repaired in that version. Such matters may affect those users who keep their AIPS up to date. These bugs often do not get reported in the AIPSLetter since they were temporary but might be of concern for diligent users. They are reported in CHANGE.DOC but those reports are sometimes fragmentary and confusing. Do not hestitate to e-mail to with any questions.


You really should be getting 31DEC21 or 31DEC21 instead of patching an older version! Information on all patches may be accessed from the patches page,

With previous releases, we did not change the frozen release tar ball; user sites were required to download the text files and do any compilations themselves. But, beginning with 31DEC04, we provide binary releases for which user sites are not required to have compilers. Therefore, we have reversed our policy. These patches have been applied to the official code of 31DEC17 and later releases and may be downloaded using an appropriate "Midnight Job". Any tarball taken after the change date listed below will already have the patches applied. Of course, you may still download and compile the files as before.

Beginning with 31DEC21, we no longer have a formal patch procedure. Corrections for serious bugs are simply applied to the "NEW" version at NRAO and may be obtained via the MNJ. The file 31DEC21 lists a brief summary of the changes made to that release while it was NEW. The file 31DEC22 lists a brief summary of the changes made to that release while it is NEW. The file CHANGE.DOC will provide information on any code changed in NEW.

There are nine 31DEC20 patches.
  1. SPLIT and CLIP would always say not calibrating things despite the user's adverbs. 2021-01-20
  2. SPRMS slightly mislabeled the Y axis and the frequency. 2021-03-23
  3. CLIP generated a false error message. 2021-04-14
  4. VLBARUN needed to set IMSIZE after UVPLT call, also allow PostScript output. 2021-04-27
  5. UVPLT could decide to plot phases from 0 to 360 ignoring the user specified plot range. 2021-04-27
  6. LISTR showed velocities for single-source files incorrectly. 2021-04-27
  7. BPASS could change reference antenna in the middle of a spectrum. 2021-07-16
  8. TVFLG, SPFLG, FTFLG did not define enough memory. 2021-07-26
  9. IMAGR could quit at the start when a flux limit was specified with auto boxing2021-10-22


... will be of interest to you if you want the latest versions updated nightly, weekly, or occasionally. It can do either text or binary updates depending on which sort you did with

NVSS and WENSS/WISH Survey files for AIPS

The WENSS/WISH files have been corrected (2 July 2004) to omit the sources which are the sum of other "components" also appearing in the lists. Note that the survey files shipped with AIPS releases include the shorter lists of the stronger sources. The full lists are only available from this ftp site.


AIPS Memos, Reports, old AIPSLetters, the Cookbook, Going AIPS, access to the newest versions of the HELP files, search CHANGE.DOC and more. The most recent AIPS Memos are:

  • number 124, discussing TVIEW, a new task for exploring image cubes, revision dated October 18, 2019,
  • number 123, discussing the new pulse-cal cabilities of DiFX and AIPS, revision dated November 21, 2018,
  • number 122, discussing the usage of AGAUS and ZAMAN spectral absorption modeling tasks, revision dated May 6, 2020,
  • number 121, discussing the usage of the UFLAG gridded data flagging task, dated September 12, 2016,
  • number 120, discussing the usage of the TVSPC data exploration task, revision dated October 18, 2019,
  • number 119, discussing the usage of the TVSAD Gaussian modeling task, dated December 15, 2014,
  • number 118, discussing the usage of XGAUS, ZEMAN, and RMFIT spectral modeling tasks revision dated May 6, 2020,
  • number 117, discussing the detailed FITS format used by AIPS, revision dated February 1, 2023,
  • number 116, discussing new RFI mitigation options in AIPS, dated June 2010,
  • number 115, discussing new auto-boxing for Clean capabilites in AIPS, dated June 29, 2009,
  • number 114, re-stating the FITS-IDI convention with corrections and added tables, revision dated Jul 19, 2022,
  • number 113, discussing a "new" geometric way to handle the W problem, dated May 22, 2009,
  • number 112, discussing the AIPS pipeline for VLA data reduction, dated March 19, 2007,
  • number 111, discussing phase referencing with more than one calibrator using ATMCA, dated January 6, 2005,
  • number 110, discussing strategy for removing troposppheric and clock errors using DELZN, revised October 21, 2009, dated August 31, 2004,
  • number 109, discussing AIPS on DVDs and read-only data systems, dated January 20, 2004,
  • number 108, discussing weights for VLA data, dated January 21, 2003,
  • number 107, discussing the differences between FRING and KRING, dated April 8, 2002,
  • number 106, discussing the Brandeis scheme for making movies in AIPS dated June 6, 2001,
  • number 105, discussing the new RUN file to simplify VLBA data reduction dated February 28, 2001 and April 26, 2001,
  • number 104, discussing the new Y2K performance test dated September 8, 2000, and
  • number 103, discussing data weighting in AIPS dated 2000-03-21.


The AIPS group maintains three e-mail exploder lists. The first, called daip, is restricted to immediate members of the AIPS group and a few NRAO scientist advisors. The other two are, however, open to any suitable person. Membership is moderated, of course, because SPAM has become so annoying.

The group intended for discussion of AIPS issues is called bananas and is used, among other things, to announce patches to the "frozen" versions of AIPS. Traffic is light. You can subscribe yourself to this list on-line.

The group intended for discussion of problems related to the "Midnight Job" is called mnj and is used to announce AIPS Manager things related to the current MNJ. Traffic is light, but the announcements can have a serious impact on any site attempting to stay current with the development version of AIPS. You can subscribe yourself to this list on-line.


The FITS Interferometry Data Interchange format is a set of FITS binary table definitions and a set of conventions for using them to transport radio interferometry data between different software packages.

The FITS Interferometry Data Interchange Convention (formerly Format) has been accepted 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, Eric Greisen had to re-type the document. While doing so, he 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 AIPS Memo 114 revised (ps) or AIPS Memo 114 revised (pdf); it has been submitted to the IAU FITS Committee. Greisen has attempted to highlight the changed parts in red in this draft. The current draft is dated July 2022 and includes the MODEL_COMPS table and comments from Lorant Sjowerman, Bill Cotton, and others. Please e-mail with comments.


Help for the weary AIPS Installer. Very much experimental and incomplete, and probably needs updating, but better than nothing.

BENCHMARKS (the "DDT" and now the "Y2K")

The AIPS Benchmark was known as the "DDT" (Dirty Dozen Tasks); we have results for a variety of systems. A more modern test called "Y2K" has been developed in 2000 to test faster computers and to use IMAGR rather than MX. For 31DEC10 we have new master images and data sets. In addition, we have a new HUGE test using multi-resolution IMAGR on Cygnus A. Changes to CALIB and VTESS in particular forced this update, while faster computers make Y2K LARGE run in as little as 31 seconds (Mac Mini with ARM M1 chip)!


The former designated-AIP-of-the-week program rotation has been halted due to the lack of personnel. The e-mail address ( was the best method of reaching all the members of the AIPS Group and will still work. However, we ask you to use the new NRAO-wide helpdesk instead. Go to and login with your username and password. There you may peruse the "knowledge base" (currently empty), enter new tickets in any of several departments including AIPS, and review and update any tickets you have submitted.

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From our last weekly meeting (restricted to NRAO intranet and friends; if you can read this, you're on the inside).


AIPS is copyrighted by Associated Universities, Inc. using the GNU copright form. The full text is available with every AIPS release and may be read here.



This is the Flexible Image Transport System, and is the standard data interchange format used by most Astronomical Software, including AIPS. Follow the above reference for a very extensive set of documentataion, including a large resource list for Astronomy on the internet.


The primary AIPS address is the daip one referenced on our main Contact page, and general queries, requests for distribution tapes, documents, ftp access, and so on should be directed there. Application-oriented questions should be directed to the Designated AIP.

Modified on $Date: 2024/01/09 17:41:15 $
Eric W. Greisen