AIPS quarterly report, 26 December 1996
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system
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Early November the 15OCT96 version of AIPS was released to the outside
world. As usual, the ``AIPSletter'' describing many of the changes and
improvements, was written and distributed.

The AIPS DDT was used extensively to test new architectures considered
for purchase by NRAO. A DEC Alpha machine reached the highest AIPS
mark thus far, namely 12.0. It was decided to purchase 7 Sparc Ultra-2
dual processor machines. Earlier tests had shown that these machines
are capable of an AIPS mark of 9 per processor. AIPS benchmarks of
multiprocessor systems at NCSA were less successful, partly because
AIPS code is not parallelized enough to make use of many processors at
once.


software
--------

Most of the software development of the last three months went into
the 15OCT95 release. Since then, the emphasis of software development
was on orbiting VLBI, in view of the upcoming launch of the Japanese
VSOP satellite. Some highlights:

1) New polarization correction modes DOPOL=2 and DOPOL=3 were
implemented. This allows second order polarization corrections when
using the linear D-term approximation within AIPS. The mode DOPOL=3
applies more rigorous flagging, removing visibility points with any
missing polarization correlation pairs, whereas DOPOL=2 applies the
same second-order correction but makes several approximations for any
missing polarization correlation pairs when computing the correction
matrix. DOPOL=1 makes the same first-order correction as before.

2) Work on the VLB DDT continued, and the following features were
added: a) instrumental polarization errors; b) multiplicative gain
errors; c) rest frequencies and LSR velocities in the SU table and
catalog header; and d) baseline-dependent integration times.

3) Elevation interpolation, which was introduced in 15OCT96 AIPS, was
further enhanced by adding the possibility to fit for opacity.

4) As always, numerous smaller improvements were made and bugs were
fixed. The designated AIP program continues to allow users worldwide
quick access to AIPS support.


personnel
---------

It was agreed that Eric Greisen would continue working outside the
AIPS group, but would be ready for consultation for whatever new
developments we decided to import into AIPS TST. We hope to be able to
hire one new position in the AIPS group in the beginning of 1997 in
order to offset the losses of both Greisen and Adler in 1996. In the
meantime, we are planning to structure the port of selected routines
from Greisen's system to AIPS TST.