AIPS

Key Developments

1. AIPS has been ported to the McIntosh OS/X operating system.  At
present, it appears that it is not making optimal use of the hardware,
since the AIPSmark is lower than expected for the speed of the
processor.  Investigation of the tuning of the software for McIntosh
has been halted, due to the lack of a modern McIntosh machine in the
AOC.

2. Various bug-fixes and improvements have been made in the task
CONFI, which is used to optimize array configurations.  Many of the
changes are associated with improvements in the algorithm that
searches for the worst sidelobe and modifies the configuration to
attempt to reduce that sidelobe.

3. UVSIM was modified to remove unused code, as well as changing the
observation date and observing epoch to January 1, 2000.  A true IAT
time calculation was added based on the input coordinates of the
observing array.  The related task UVFIX was modified to make correct
calculations for the GMRT, whose coordinate system (u,v,w) seems to be
opposite from the VLA and other definitions.  The investigation of the
GMRT coordinate issue exposed various other bits of inefficient or
erroneous code which were dealt with.

4. A number of small modifications were made to the VLBA
data-calibration utilities, both for clarity and to correct small bugs.

5. Various changes were made to FILLM to make the reading of VLA data
from disk a more robust process.  Testing was done on modifications of
the portions of FILLM that allow filling of data as it is observed.
Significant improvements in robustness have been achieved, which will
be released for general use early in the second quarter.

6. Investigation into improved smoothing, blanking, and interpolation
of calibration tables was begun.  The code and the techniques are
rather complicated, so substantially revised tasks have not yet been
entered into the system.

7. An investigation into possible improvements in phase calibration
using externally supplied troposphere calibration was begun.

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Goals for Second Quarter 2003

We anticipate a reduction in completion of new capabilities during the
second quarter, due to a long vacation for the lead AIPS software
developer.  The following efforts are expected:

1. Continue user support and bug fixes, as the major portion of AIPS
effort.

2. Add the more robust code for real-time filling of VLA data into the
system.

3. Continue investigation of improved smoothing and blanking in
calibration.

4. Continue the moderate-term project to explore improved troposphere
calibration.

5. Add Tsys values for a single VLA antenna into the calibration data
supplied with VLBA correlator output.

6. Test and enhance AIPS performance on McIntosh computers with the G4
processor (dependent on availability of a machine for testing).