Dear PI, We have examined the data for project RDV57 on 11 Jul. 2006. The contact person for this project was Craig Walker. The archive key is eWAnuuwJ. Here's a summary: 1. Tape weights vs. time plots have been generated for the entire time range of your experiment. These are a measure of tape record/playback quality, representing the fraction of valid data samples. Data with weights below 70-75% should be flagged. However, you may want to be more cautious when dealing with non-VLBA stations. The easiest way to estimate the best weight threshold is by looking at the tape weights vs. time plots generated here. You can find the weights plots at /home/vlbiobs/astronomy/jul06/rdv57/sniffer/final/wtsfile.ps. If your experiment involves more than one distribution tape then there will be a tape# subdirectory between /final and wtsfile.ps. See /home/vlbiobs/README.sniffer for instructions on how to interpret this plot. 2. Delay, rate, phase, and amplitude plots were made for the observation. 3. Autocorrelation bandpass plots were generated for all antennas for scans on all sources. 4. Cross-correlation bandpass plots were generated for all baselines to AP, FD, HN, HO, LA, MK, NY, OV, SC, WZ for scans on all sources. 5. Gzipped PostScript plots of Tsys and other monitor data for each available VLBA antenna can be found at /home/vlbiobs/astronomy/jul06/rdv57. 6. The jobs associated with the correlation of RDV57 can be found at: /home/vlbiobs/astronomy/jul06/rdv57/jobs. These files provided the correlator with all ancillary data needed for VLBI, including: correlation parameters and telescopes correlated in the final production. The job numbers are: pass1: 1119-1134; pass2: 1140-1153; pass3: 1160-1175; 7. Operations staff have devised a web browser to navigate the file server vlbiobs, as well as view and retrieve its text and PostScript files, gzipped or not. This browser can be reached through the VLBA homepage http://www.aoc.nrao.edu/vlba/html/VLBA.html, initially under Data Analyst but then under Aspen. All of the files mentioned above can be accessed either with this browser or by FTPing to the vlbiobs account on vlbiobs. Automated Calibration Transfer for VLBA Correlator Output --------------------------------------------------------- The first phase of automated calibration transfer for data from the VLBA correlator has been completed, and was used for your observation. This transfer of calibration information includes data from the 10 VLBA antennas, as well as selected information from the VLA and Effelsberg, which currently provide VLBA-style monitor data. Significant changes to AIPS have been required to introduce calibration transfer, so users must have the patched version of 15OCT98 AIPS, or any later version, beginning with 15APR99. Help files for a number of AIPS tasks have been updated to reflect the new calibration procedures. There also is a new version of the VLBI chapter of the AIPS cookbook, available from http://www.cv.nrao.edu/aips/aipsdoc.html, that includes more details on how to cope with the calibration transfer process. The calibration-transfer process relieves observers of the burden of creating and inputting calibration files for VLBA antennas. Instead, this information is now provided as tables attached to the FITS data sets output by the VLBA correlator. The ancillary data include antenna gain (GC table), system temperature (TY table), pulse calibration (PC table), flags (FG table), and weather (WX table). The wise observer will not modify these original tables; processing errors might then force the data to be reloaded using FITLD. See the description of MERGECAL in Section 9.2.1.7 of the new cookbook chapter for more detail. Of course, skeptical users can simply delete the appropriate tables created by FITLD and generate their tables in the old manner. Phase 2 of calibration transfer will include supply of data from more external telescopes, and probably will proceed incrementally, depending on both the availability of the external information and the implementation of new software in Socorro. At present, ancillary data from most external telescopes must still be loaded in the old manner, and observations of strong sources may be needed for manual pulse calibration at those telescopes. Up-to-date instructions on coping with observations including external telescopes can be found at http://www.nrao.edu/vlba/html/OBSERVING/cal-transfer/cal-transfer.html. Please send comments on calibration transfer to julvesta@nrao.edu, and send bug reports to daip@nrao.edu, with a copy to julvesta@nrao.edu. NOTES: This was the first multi-pass correlation of RDV done here, and although it took longer, it went well. No trials were run, though a pilot for each pass was evaluated to determine if any problems were apparent. The stations were divided into three groups of five and two different groups were processed with each pass. One station, LA, was put into all three passes, so pass three has eleven stations instead of ten. There was some delay before starting correlation due to the initial absence of the AP log and resolution of a discontinuity in the WZ log. Also apparently due to some discrepancy between the field system logging and the actual disk directory, the HO disk failed to start within the initial job when scheduled. This was resolved by breaking the job to start with the first recorded data on the HO disk. There was an additional job created, number 1119, to pick up the first few minutes in the first pass. No data was lost, and this correction was applied to the other pass with HO Residual delays were low or nominal except for HO. The fixed offset applied to HO resulted in a residual offset of ~600 nano seconds. An adjustment will be made for future correlations. Down time: SC was out for dewar work 17:58 to 19:20; dewar was cooling 19:20 to 22:28; down for circuit breaker fault 01:53 to 02:35; WF did not participate due to power problems. WZ down for dewar work 18:07 to 23:40; Group and pass plot: A B C -------------------------- 1 AP KP NY 2 BR LA OV 3 FD MC PT 4 HN MK SC 5 HO NL WZ PASS 1 = A-B PASS 2 = B-C PASS 3 = A-C w/LA 1119-1134 1140-1153 1160-1175 Total data for three passes = 8.68 gigabytes RDV57 was released August 1st, 2006. The total correlation time was 39.9 hours.