[daip] draft Visiting Committee report for comment

[Eric Greisen]

          March 2005 Visiting Committee Report on AIPS

The 31DEC04 version of AIPS was developed through 2004 and then frozen
in late December.  It was available for download (and update via the
"midnight job" or MNJ) during development and the frozen version may
now be downloaded.  The new test version, 31DEC05, was started in
December 2004 and is available for download and update.  We have
developed tools to count downloads of full AIPS versions and to count
access to the main "cvs" site.  The latter reflects both initial
installation and updating of the development version; frozen versions
do not generate cvs accesses.  Counting each unique IP address as a
"site", there were cvs contacts from 797 sites in 2004 of which 231
appear to have run the MNJ at least occasionally.  The frozen 31DEC03
version was downloaded by 196 sites and the 31DEC04 version, while
under development, was downloaded by 808 sites.  A total of 1276
unique IP addresses downloaded a copy of AIPS and/or accessed the cvs
site.  At this writing (15 February), the frozen 31DEC04 version has
been downloaded by 69 sites and the development 31DEC05 version has
been downloaded by 190 sites.  The total number of IP addresses is
already 364.

We have found that the Fortran compiler developed by IBM for MacIntosh
systems generates code that is 50% faster than that produced by the
GNU compilers.  Unfortunately, the IBM compiler is moderately
expensive. Therefore, we have made available a binary distribution of
AIPS.  This binary form is available both for the frozen 31DEC04
release and the development 31DEC05 version, including periodic
updates (daily are possible) via the MNJ.  For completeness, binary
installations are available for MacIntosh OS/X (IBM compiler), SUN
Solaris (SUNWspro compiler), and Intel Linux (GNU 2.95.3 compiler).
The Intel compiler for Linux has recently been tested.  It failed to
work with aggressive optimization and, with less optimization, its
performance was only slightly better than that of the GNU compiler.

Steps are being taken to support greater use of pipeline and other
procedures in AIPS.  A large task FLAGR was written to use the
internal statistics in a data set to flag that data set.  The new task
FINDR was written to determine some of the same statistics, returning
values to the AIPS user.  Studies are now underway to determine how
these tasks may be used in AIPS' VLA and VLBA data reduction
pipelines, particularly in flagging calibration sources.

Models for the primary flux calibration sources are now provided with
AIPS.  There are four sources, 3C48, 3C138, 3C147, and 3C286, at the
three highest VLA frequency bands, K, Q, and U.  These models were
provided by Claire Chandler.  X-band (3.6-cm) models for 3C48 and
3C286 and a C-band (6-cm) model for 3C48 have been provided so far by
Amy Mioduszewski.  We expect, in the long run, to provide models for
all four sources at all VLA frequencies.  The pipeline procedures for
the VLA are being revised to use these models.  The verb CALDIR to
list available models and the task CALRD to read in models were added
to AIPS.

The calibration and bandpass tasks, CALIB and BPASS, were revised to
offer "robust" gain solution methods.  Such methods progressively
refine solutions by ignoring significantly discrepant data at each
iteration.  This change in the fitting routines provides data to allow
CALIB to flag data with significant closure error.  BPASS was changed
to handle channel-dependent flagging correctly.

A new task, ATMCA, was written to refine the calibration during
phase-referencing observations through the use of additional
calibration sources.  The direction-dependency of phase error is
fit from the multiple calibration observations and used to refine the
gain solution on the target source.  AIPS Memos on ATMCA and the
earlier DELZN astrometric-level calibration tasks were released.
Note that both these tasks require observations to be scheduled to
provide the additional calibration information required to model the
atmospheric direction dependency of phase.

The AIPS CookBook was kept up to date a s always.  In addition, it was
developed so that, in addition to the usual PostScript version, both
html and pdf versions exist.  The latter provide full cross-reference
capability including using the web browser to examine cross-linked
help files.  This XHELP facility was corrected and greatly enhanced
during 2004.

In the past, when the Midnight Job detected changes in certain
system-like files, all the AIPS Managers were alerted and instructed
to perform a variety of manual operations.  The MNJ procedures were
changed to do almost all of these automatically, greatly simplifying
the Managers' job.  The installation from CDrom was tested and
corrected.  It is actually pretty slick.

The new task FIXBX converts Clean windows from one set of cell size
and facet locations to another.  New tasks to renumber frequency IDs
and sources were written.  New verbs to draw Clean boxes on the TV, to
return random numbers, and to provide direct access to the operating
system were added.  The last has interesting implications for
pipelines and can even run an AIPS beneath the current one.

Task upgrades included a number of changes to IMAGR to enable the
Steer-Dewdney-Ito Clean algorithm to be used efficiently.  The complex
Clean task and procedure (CXCLN and CXPOLN) were corrected.
On-the-fly imaging is still done at the 12-m telescope and AIPS can
now handle the new, changed data format as well as the older one.
All plot tasks and verbs that used the Tektronix-emulation window now
offer a TV-window equivalent.  The VLA data filling task FILLM was
changed in numerous small ways to handle various error conditions, to
deal with multiple data sets from the archive, and to precess
coordinates in a manner consistent with the rest of AIPS.