Dear PI, We have examined the data for project RDV52 on 24 Aug. 2005. The contact person for this project was Craig Walker. Preliminary notes and information: WEIGHTS AP: Station observed different mode; did not correlate. GC: Station observed different mode; did not correlate. PT: Problem with the azimuth motor at the site at 22:57 - 00:12 UT; no data during this time range; see VLBA operator's log. SC: Station out with azimuth motor problems at 00:52 - 2:07 UT; no data during this time range; see VLBA operator's log. Variable weights at roughly 5:00 - 14:00 UT; weights vary between 10% - 100% but usually remain good near 100%; the tape was moved to a different playback drive during correlation with no improvement seen. GG: Poor weights at roughly ~5:00 - 14:00 UT; weights vary between 0% - 100%; tape was moved to a different playback during correlation with no improvement seen. KK and WZ: Out for intensive run at roughly ~17:59 - 20:00 UT; no correlated data during this time range. AUTOCORRELATION RFI seen in most 13 cm channels at most VLBA stations. Scattered RFI spikes seen in a few channels at the non-VLBA stations. CROSS_CORRELATION & RAPD All stations are fringing. GG: Intermittent fringing and high phase slope (delay) seen in the cross correlation plots. High delay (450 ns). TS: High delay (-270 ns). _____________________________________________________________________________ Correlation Summary for RDV52: Preparation complete: Sep 09, 2005 Preparation Hours: 0 Correlation Hours: 16.5 Date of Correlation: Sep 14-15, 2005 Date of Release: Sep 16, 2005 _____________________________________________________________________________ 1. For possible problems and additional information which may have affected this observation, please consult the VLBA System Monitoring page located at the Internet URL: http://www.vlba.nrao.edu/astro/VOBS/astronomy/vlba_sysmon.html Select (click on) the link for the 2005 VLBA System Monitoring Calendar. Then select (click on) the monitoring project code(s) 'MT***' that observed during the concurrent week for this observation. This will display the selected monitoring project directory where a report summary named monitor.txt can be viewed or retrieved. This directory also contains useful plots under reference antenna subdirectories. 2. 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 at http://www.vlba.nrao.edu/astro/VOBS/astronomy/. All of the files mentioned above can be accessed either with this browser or by FTPing to the vlbiobs account on vlbiobs. 3. Tape weights versus 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 http://www.vlba.nrao.edu/astro/VOBS/astronomy/aug05/rd000/sniffer /wtsfile.ps. If your experiment involves more than one distribution tape then there may be a tape# subdirectory between the /sniffer and wtsfile.ps. See /home/vlbiobs/README.sniffer for instructions on how to interpret this plot. 4. Delay, rate, phase, and amplitude plots were made for the observation. 5. Autocorrelation bandpass plots were generated for all antennas for scans on all sources. 6. Cross-correlation bandpass plots were generated for all baselines to LA for scans on all sources. 7. Gzipped PostScript plots of Tsys and other monitor data for each available VLBA antenna can be found at: http://www.vlba.nrao.edu/astro/VOBS/astronomy/aug05/rd000. 8. The jobs associated with the correlation of RD000 can be found at: http://www.vlba.nrao.edu/astro/VOBS/astronomy/aug05/rd000/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: 5220 - 5250 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. It is highly recommended that users download the 31DEC03 version of AIPS to take advantage of new tools and current updates. 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. 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.vlba.nrao.edu/astro/obscor/cal-transfer/. 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. End of Letter