[daip] draft Visiting Committee report

[Jim Ulvestad]

Hi Eric,

I think it's likely that we will end up shortening this, but it depends
what happens when I see how it fits with the other material in
a couple weeks.  Before I attack it in the penultimate version, you
might think about whether there are obvious things to shorten.

Jim

Eric Greisen wrote:

>          March 2006 Visiting Committee Report on AIPS
>
>The 31DEC05 version of AIPS was developed through 2005 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, 31DEC06, was started in
>December 2005 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 982 sites in 2005 of which 252
>appear to have run the MNJ at least occasionally.  The frozen 31DEC04
>version was downloaded by 246 sites and the 31DEC05 version, while
>under development, was downloaded by 832 sites.  A total of 1460
>unique IP addresses downloaded a copy of AIPS and/or accessed the cvs
>site.  At this writing (21 February), the frozen 31DEC05 version has
>been downloaded by 76 sites and the development 31DEC06 version has
>been downloaded by 214 sites.  The total number of IP addresses is
>already 425.
>
>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.  On Pentium IV machines, the code generated by the
>Intel compiler is 30% faster than that generated by the GNU compilers.
>In fact, The Intel-compiler binaries are also about 7% faster on
>non-Intel machines (AMD 64s).  A similar speed up is seen with the SUN
>compiler on Solaris machines.  Unfortunately, these compilers are
>moderately expensive. Therefore, we have made available binary
>distributions of AIPS.  This binary form is available both for the
>frozen 31DEC05 release and the development 31DEC06 version, including
>periodic updates (daily are possible) via the MNJ.  So far in 2006, 90
>sites have accessed the binary version of 31DEC06 and 46 sites have
>accessed the binary version of 31DEC05.
>
>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.  Lower frequency models at X, C, and L
>bands for 3C48 and 3C286 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.
>
>Steps are being taken to support greater use of pipeline and other
>procedures in AIPS.  The new experimental task FLAGR uses the internal
>statistics in a data set to flag that data set.  It was corrected to
>flag times at which it fails to find antenna-based amplitudes, phases,
>and weights from the baseline data.  With this correction, it appears
>that the task is quite effective in flagging calibration sources and
>it is being incorporated into new pipeline procedures.
>
>The VLBA correlator requires an estimate of the Earth Orientation
>Parameters in order to correlate an observing session.  Unfortunately,
>the final best estimates of these parameters are usually not available
>at correlation time.  For a period of time, the VLBA correlator used
>very preliminary estimates rather than better estimates which were
>available by correlation time.  AIPS task CLCOR was given a new option
>to read the final best EOP estimates and correct the data to those
>from the EOP values used at correlation.  An AIPS procedure was
>written which fetches these estimates from the web and then runs this 
>CLCOR option.
>
>Because of a shortage of disk playback units at the VLBA correlator
>and limitations in the instantaneous bandwidths which may be
>correlated, the old AIPS tasks VBMRG and VBGLU are again needed.  They
>have had various bugs and limitations corrected and VBGLU is about to
>be rewritten so that no data are lost in the process.
>
>AIPS uses dynamic memory to allow for large-memory problems without
>burdening normal uses of quite a number of tasks.  The code was
>revised to support those 64-bit addressing computers which allocate
>dynamic memory at virtual addresses well removed from the virtual
>addresses assigned to the pre-compiled code.  AMD-64 computers under
>Linux are among this class and NRAO has acquired one to support this
>architecture in aips++ (and AIPS).
>
>Miscellaneous enhancements including generalizing all tasks which
>handle box files so that they support all box and field definitions
>used by IMAGR.  The new task CCRES allows the addition or subtraction
>of Clean component models in images without requiring power of 2
>images and point sources exactly on image cells.  The remaining
>Tektronix emulation tasks, including XGAUS and XBASL, were revised to
>offer more reliable TV-based methods.  A spectral-index fitting task
>was written and other tasks revised in anticipation of problems with
>spectral index over the very wide EVLA bandwidths.  A spectral-index
>correction method is being added to IMAGR.
>
>Full information on AIPS may be found beginning at the main web page
>     http://www.aoc.nrao.edu/aips/
>
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