AIPS: 2nd Quarter 2003

Key Developments

1. FILLM, the task that reads VLA archive data into AIPS, was improved in several ways. The ability to read the data in real time was made substantially more robust, continuing to work through shutdowns at the VLA and other disruptions. It has the options to use somewhat more correct weights and omit data for which the last reference pointing failed.

2. The tasks which smooth calibration data were given much more flexible smoothing options. In particular, CLCAL, which merges and smooths calibration solution tables and applies the result to the master calibration table, was revised to give the user much more control over the smoothing operation. CLCAL was revised to give the user more control over which solution tables are merged and to allow a sensible merge/smooth operation to be done for single-source files.

3. New verbs to draw lines on the TV based on image pixels rather than TV pixels, to convert between these units, and to measure distances between image pixels were written. The image statistics routines IMEAN and IMSTAT can now operate on round apertures as well as rectangular.

4. The moment fitting task MOMNT has been corrected to handle blanked pixels and to do a primary beam correction on the cutoff value.

5. The suite of array simulations tasks was increased with a new task to compute the loss of sensitivity due to antenna shadowing.

6. A few minor corrections were made so that AIPS will compile on the latest Linux systems from RedHat.

Goals for Third Quarter 2003

The following efforts are expected:

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

2. Revise the real-time filling of VLA data into AIPS using a system that fills the disk archives in real time.

3. Add more flexible colored-line drawing to the AIPS plotting package to allow multiple colors to represent, for example, velocity or position angle or simply to differentiate multiple IFs combined in a single plot.

4. Investigate the use of overlapping solution intervals to minimize lobe ambiguities in fringe fitting.

5. Continue the moderate-term project to explore improved troposphere calibration. Develop methods for fitting and correcting residual zenith delay.

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

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