Subject: results from VT906 Dear PI, We have examined the data for project VT906 on 06 Nov. 1997. 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. 2. Delay, rate, phase, and amplitude plots were made for the observation. 3. Autocorrelation bandpass plots were generated for all antennas for scans on '2021+614'. 4. Cross-correlation bandpass plots were generated for all baselines to EB for scans on '2021+614'. 5. Weather and Tsys plots for the VLBA antennas for your project will be sent with the data tape(s). NOTES: Note to PI: VSOP experiment V085m failed almost completely due to a problem in the VSOP attitude control software. This was recovered in time to get one hour of VSOP tracking at the end of V085m, using the Tidbinbilla tracking station. With approval from the VSOG, we are sending the data from VT906, which observed the same source 9 days earlier, and used the VLBA and Y in addition to the EVN. (This is actually a much better experiment, with lots of tracking time.) The last hour of V085m was also correlated and will be sent separately. The earlier ground-only parts of V085m will not be correlated. GZ - Tracking and fringes from 2200 to 2339. Time Correction File was continuous, with only one clock-setting event before 2200. Residual delay is 275 nsec until 2220 (this is IF 1; IF 2 is 50 nsec less), then jumps to 650 nsec for the rest of the pass, with a few-minute excursion to 775 nsec at about 2250. Fringes got quite weak near 2300, requiring VLA or EB for detection, apparently due to a visibility minimum. TZ - Tracking and fringes from 0227 to 0700. There were several clock-setting events, at times indicated by the following summary of the Time Corrections File: valid start, stop = 1997NOV07_02h27m57.30s 1997NOV07_02h42m26.90s valid start, stop = 1997NOV07_02h42m28.30s 1997NOV07_02h53m36.90s valid start, stop = 1997NOV07_02h56m07.30s 1997NOV07_04h47m40.10s valid start, stop = 1997NOV07_04h48m11.30s 1997NOV07_04h59m39.90s valid start, stop = 1997NOV07_04h59m42.30s 1997NOV07_06h59m57.90s Small delay jumps of size 50-200 nsec occur at the breaks between tables, so it may be useful to break fringe fits at the breaks where these clock-setting events occur. In general, the residual delay ranges from -250 to around 0 nsec. The rate residual takes a dive to nearly -100 mHz near 0700, as the spacecraft approaches perigee, which occurs at 0727. There are fairly small DC spikes in both channels. JB - The tape from JB never synchronized. Quite a lot of troubleshooting by our recorder engineer indicated that at least the first 12 tracks and track 21 are completely dead. The track power gradually increases from tracks 13 through 18, with the higher numbered tracks (except for 21) being okay. JB was left out of the final correlation. TR - The TR recording was terrible, with tracks 2 and 27-33 being bad. IF 1 has an enormous DC spike, leading to fringes being quite a bit noisier in this IF than in IF 2. ON - Recording is okay. There appears to be an intermittent telescope (pointing?) problem which causes fringe amplitude to be a factor of 40 or so weaker in much of the first half of the observation, with fringes detectable only to EB and Y. The problem seems to have cleared up in the second half of the run. MC - Recording quality was intermittent because of a faulty capstan. Data are therefore missing for periods of tens of minutes to an hour at a time. NT - There are a couple periods of slightly degraded recording (also for ON). Otherwise, there are no obvious problems. EB - There is a weak DC spike in IF 2. Recording is excellent, except for a slight degradation in the first reverse pass (even-numbered tracks) at each head position. For an unknown reason, the SNR of the FRING peak in IF1 is no more than 40% of the value in IF 2 on the baseline to the phased VLA. This appears to be caused by EB rather than Y, since the Y fringes to the spacecraft show no such effect. VLBA and Y - Good recording at all sites. No significant problems noted in observing log; all stations show good fringes. *************************************************************************** Subject: V085M results Dear PI, We have examined the data for project V085M on 16 Nov. 1997. 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. 2. Delay, rate, phase, and amplitude plots were made for the observation. 3. Autocorrelation bandpass plots were generated for all antennas for scans on '2021+614'. 4. Cross-correlation bandpass plots were generated for all baselines to EB for scans on '2021+614'. 5. Weather and Tsys plots for the VLBA antennas for your project will be sent with the data tape(s). NOTES: Only the last hour of this experiment was correlated, since that was the only hour when the spacecraft was working. The PI will receive the data from VT906 in addition to V085M. TZ - Decent fringes at -210 nsec relative to EB. No delay jumps; only 1 clock-setting event. Fringes moderately weak, sometimes requiring several minutes solution interval to detect in FRING. EB - Weak DC spike in Channel 2; otherwise no notable problems. GB - Good recording, no problems, fringes at -335 nsec relative to EB. NT - Good recording, no problems, fringes at +40 nsec relative to EB. ON - Shaky recording in first of 3 passes that were correlated. Fringes at -470 nsec relative to EB. No obvious amplitude problems this time. MC - Degraded weights on 1st and 3rd scans correlated. Perhaps this is still the capstan problem? JB - Dead channel on 2nd pass correlated, so weights are down at 0.5. No fringes anywhere. Possibly, this is related to the +/- 3 msec offset reported for some other experiment, but that's unclear. No further investigation planned. Reminder - only the time from 0400 to 0500 on 17 November was correlated. -------------------------------------------------------------------------- Subject: V014B1 released Dear PI, We have examined the data for project V014B1 on 14 Nov. 1997. 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. 2. Delay, rate, phase, and amplitude plots were made for the observation. 3. Autocorrelation bandpass plots were generated for all antennas for scans on . 4. Cross-correlation bandpass plots were generated for all baselines to EB for scans on . 5. Weather and Tsys plots for the VLBA antennas for your project will be sent with the data tape(s). NOTES: Comments on Individual Stations: ================================ GB does not fringe from 10:00-13:45 EB no fringes 8:30-9:00 and 10:45-11:00 DC spike in 2nd IF JB 2nd IF low amp gap in data from 9:37-10:36 (field system crash) MC 2nd IF dead from 4:00-4:22 ON very poor playback fist 4 hours -poor/dead on tracks 2-8, 16, 20-22. TR very poor playback 2nd IF dead no data after power failure at 7:14 Comments on HALCA: ================== RZ large DC spike TZ failed UZ did not provide a time corrections file, was left out of correlation Recommended fringe fit intervals: ================================ Since tracking station time setting events cause jumps in delay, we recommend fringe fitting between clock setting events (rather than across clock setting events). Below is a list of the start and stop times of separate tables in the Time Corrections File (TCF) provided by the tracking stations. Each table starts at a clock setting event. table start, stop = 1997NOV14_10h59m42.50s 1997NOV14_11h55m12.00s table start, stop = 1997NOV14_11h55m19.50s 1997NOV14_12h57m58.00s *************************************************************************** Subject: V330C PI letter Dear PI, We have examined the data for project V330C on 10 Nov. 1997. 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. 2. Delay, rate, phase, and amplitude plots were made for the observation. 3. Autocorrelation bandpass plots were generated for all antennas for scans on 1954+513. 4. Cross-correlation bandpass plots were generated for all baselines to EB for scans on 1954+513. 5. Weather and Tsys plots for the VLBA antennas for your project will be sent with the data tape(s). NOTES: Tracking for the spacecraft was scheduled for Rz, Nz, and Tz. Tz tracking failed completely, i.e. there was no data recorded from that station. Fringes were detected from the spacecraft (to Eb) for tracking stations Rz and Nz. For Rz, the fringes disappear at about 15:00 UT. The amplitudes appear to show a gradual decline; we presume that this is due to source structure as there is no other reason we can determine for the loss of fringes. The fringes to the spacecraft through Rz may return at about 16:15 UT. For the Nz pass, a minimum in the amplitudes ALSO occurs (at approximately 20:00 to 20:15 UT). This also argues for source structure being the reason for the Rz loss of fringes. We didn't notice any delay glitches for either tracking station, but there are four clock-setting events for Rz, and seven for Nz; it is probably a good idea to break the fringe fits when the clock-setting events occur and so we list the times for these events. Rz - table start, stop = 1997NOV10_12h05m08.30s 1997NOV10_13h00m01.00s table start, stop = 1997NOV10_13h03m03.40s 1997NOV10_13h49m17.00s table start, stop = 1997NOV10_13h49m28.40s 1997NOV10_16h22m07.00s table start, stop = 1997NOV10_16h22m32.40s 1997NOV10_16h29m52.60s Nz - table start, stop = 1997NOV10_18h20m33.53s 1997NOV10_18h49m36.03s table start, stop = 1997NOV10_18h50m03.33s 1997NOV10_18h50m11.83s table start, stop = 1997NOV10_18h50m35.43s 1997NOV10_19h28m45.73s table start, stop = 1997NOV10_19h31m13.33s 1997NOV10_21h57m54.93s table start, stop = 1997NOV10_21h57m55.03s 1997NOV10_22h59m24.73s table start, stop = 1997NOV10_23h00m26.63s 1997NOV10_23h00m40.63s table start, stop = 1997NOV10_23h00m40.73s 1997NOV10_23h02m21.33s Weights showed that recording was very bad for most of the run at Jb and Tr. There will be little or no useful data from Jb. The recording is better for Wb. At Eb, Gb, Nt, Mc, and On, the recordings seem to be fairly good. There is no phase-cal at Tr or Wb. There is a strong DC spike at Tr in IF 1. Phase-cals at Gb seem too strong; there is a spike in the middle of the first IF at Nt. Eb has some DC spikes as well, in both IFs. The fringes from Eb to Wb show a residual rate of about 100 mHz. There was a note from Tony Foley about the clock from Wb, but it doesn't seem to address the residual rate problem. We have checked the station position that was used in the correlation and it seems that, as far as we can tell, we have it correct. After the observations were over, Gb personnel discovered that the "pump breaker on the maser had tripped, and therefore the 1PPS lost sync" during or just before the project started. Based on measurements from the site timing log, we at the correlator estimated the drift and entered this as a rate in the correlator jobs. There still appears to be some residual rate, but fringes were found Eb - Gb, and hopefully some useful data can be recovered from Gb. Good strong fringes were found from Eb to Mc, On, and Nt, although the residual delay to On was a bit high (about -450 ns). ************************************************************************8 Subject: VT907 telescope performance Dear PI, We have examined the data for project VT907 on 15 Nov. 1997. 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. 2. Delay, rate, phase, and amplitude plots were made for the observation. 3. Autocorrelation bandpass plots were generated for all antennas for scans on . 4. Cross-correlation bandpass plots were generated for all baselines to LA for scans on . 5. Weather and Tsys plots for the VLBA antennas for your project will be sent with the data tape(s). NOTES: Times noted are approximate. GB-did not sync first 45 minutes JB-playback weights poor low amplitude in second IF no signal first IF 16:45-17:00 no fringes at 03:26 (low weight) HN-weak fringes 14:00-18:00 (source structure?) MC-playback weights poor -1st IF fringes weak 16:45-17:00; 17:52-18:45; 23:20 NL-poor playback weights at the beginning of reverse passes NT-did not sync first 15 minutes ON-gap in data from 04:50-05:15 (errors in log at 4:51) no fringes 03:26-03:35; 04:10-04:30 ---------------------------------------------------------------------- Comments on non-VLBA stations: GR017X 14/15nov97 ================================================ M. Rupen 21jan98 1. MC - very weak at 8 GHz (can see fringes on fringe finders on baselines with European antennas, but never on M81 (about 100 mJy), even to the phased VLA). Noto's fringes are uniformly much stronger. 2. NT - beautiful fringes 3. GB - nice fringes 4. Y27 - LCP fringes are a factor 4 weaker at all wavelengths (4, 6cm). However, the VLA CAL file shows Tant/Tsys being very close at all times for the two pol'ns. The VLA data themselves show one oddity: antenna 1 has very high amplitudes in Stokes LL in TVFLG/UVPLT (uncalibrated), about 14000 times higher than any other antenna. Ant 1 also shows up in the TY table (SNPLT/TSYS) with similarly high values. 5. RO - tracks 22-33 always dead --> channels 3&4 and/or 7&8 missing much of the time (2nd, 4th BBCs) - long periods spent in search 6. GO - started recording over an hour late - tracks 2-5 always dead --> channels 1,2,5,6 missing most of the time (1st, 3rd BBCs) 7. EB - lovely as always ============================================================================= From analysts@aoc.nrao.eduFri Mar 27 09:12:03 1998 Date: Thu, 26 Mar 1998 14:06:21 -0700 (MST) From: Data Analysts To: p062gra@mpifr-bonn.mpg.de, vlbifriend@astbo1.bo.cnr.it, vlbifriend@ira.noto.cnr.it Cc: jive@RZMWS0.NFRA.NL Subject: GR016A.971123.sniff Dear PI, We have examined the data for project GR016A on 23 Nov. 1997. 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. 2. Delay, rate, phase, and amplitude plots were made for the observation. 3. Autocorrelation bandpass plots were generated for all antennas for scans on 3C84,3C345,1803+784,2007+777. 4. Cross-correlation bandpass plots were generated for all baselines to LA for scans on 3C84,3C345,1803+784,2007+777. 5. Weather and Tsys plots for the VLBA antennas for your project will be sent with the data tape(s). NOTES: BR:okay FD:okay HN: Antenna not used, 02:05-07:49 UT. Antenna stowed, 10:59-11:05 & 13:11-13:23 KP:okay LA:okay MK:okay NL:okay OV:okay PT: RFI in autocorrelation plots on IF #1 SC:okay Y27: Tape in search for long periods of time IF#2: No fringing on upper half of bandpass--standard setups put this channel at the edge of the normal VLA passband. RFI in autocorrelation plots on IF #1 RO: Poor weights in general--Dead tracks throughout project, long periods of time in search. IF#2 intermittently dead GO: Poor weights in general--Dead tracks throughout project, long periods of time in search. Pcal tones evident in lower part of each IF. MC: Tape in search for long periods of time EB: No data recorded from 18:36-18:55 NT: Tape intermittently in search at the beginning of the observation. Data tapes to be sent to MPIFR-Bonn. JRomney will keep tapes on hold (and undegaussed) for further testing.