To:      Phyllis Jackson

From:    Eric Greisen

Date:    1 July 1993

Subject: Quarterly Report on AIPS (1993 Q2)

     The 15APR93 release of "Classic AIPS" has been replaced with a
15JUL93 release which we expect to occur approximately on the nominal
date.  The delay is due primarily to the addition of support for Sun's
new operating system, Solaris.  For this addition, most routines
written in C in AIPS were revised to meet the ANSI standard for the C
language and many were revised to conform to basic Posix standards.
In this way, we actually reduced the number of host-specific routines
while increasing those that apply to all UNIX systems.  The system
procedure files were also revised to be more portable, general, and
reliable.  With help from other institutions, our support for Hewlett
Packard, DEC, and Cray systems was improved.  The television server
XAS was brought up to the standards of MIT Release 4 of X Windows and
the message server was made more reliable and transparently fast.

     In anticipation of upcoming major VLA surveys, two new tasks were
added.  The first (WFCLN) does wide-field, wide-band image
deconvolution taking into account frequency effects (in source
spectral index, single-dish primary beam, erroneous center
frequencies) while using an improved weighting scheme.  The second
(OHGEO) regrids the images to correct the geometry to be normal to the
phase center and to correct effects of the variation of the primary
antenna gain over the observed bandpass.  Another new and useful task
(DTSUM) provides matrix and other listings summarizing the contents of
visibility data sets.  Several data manipulation tasks were added.
These are BLWUP to blow up an image by pixel replication, IMTXT to
convert an image into a text form useful for non-AIPS programs, MULIF
to add or increase an IF axis in a data set, UV2MS to append
single-source visibility data correctly in a multi-source visibility
file, and SPECR to regrid a visibility data set in frequency using an
FFT interpolation method.  A new canned procedure VLBA may be used to
do a quick, but detailed examination of data coming from the VLBA
Correlator.

     The most serious bugs which we corrected were in the "gridded
FFT" method of computing source models.  The method did not work when
there were both rotations and shifts.  The AIPS test suite called DDT
is being changed to test for this and assure future reliability.
Baseline-based fringe fitting received numerous improvements and
corrections.  The standard fringe-fitting task was corrected to allow
division by a clean component model and changes were made to allow
such models to be used more easily in normal gain calibration.  Task
ANCAL which applies user-supplied, antenna-based calibrations to the
data was overhauled and the general FITS reader FITLD was corrected
for a number of problems including failure to catch parts of non-AIPS
headers.  UVPLT and other tasks were corrected to stop them from
plotting every point twice.  The AIPS tasks to convert plots and
images to Postscript were generalized in the grey level of overlay
lines (LWPLA) and in the handling of color lookup tables (TVCPS).
Finally, a new verb TVPHLAME was added to do flame-like pseudo
coloring on AIPS' TV displays.



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