CA083 #2839 tar-save will be created
2000 Apr 18-19 Processing factor = ??
DOY 109-110 97% have fourfit Quality Codes of 5-9.
Algonquin: No phase cal, so fringed with manual phases.
Gilcreek: OK.
HartRAO: OK.
Hobart: High clock rate: 10 ps/s.
Matera: Strong S-band RFI in ~8% of scans, particularly in channel S3.
Tsukuba: OK.
QC=5-9
AI 94% A - Gilcreek
AT 97% G - Algonquin
GA 98% H - Hobart
HT 97% I - Matera
JH 96% J - HartRAO
T - Tsukuba
*******************************************************************************
CA083 (2000 April 18-19)
========================
Correlator notes:
Algonquin: No phase cal, so fringe with manual phases.
Hobart: Clock rate 10 ps/s.
Matera: Strong RFI in S channel 3 in some prepass scans.
There are of order 70 scans in the production pass for which fringes
are missing for all or part of the scan in a single channel. They
appear to be due to a correlator fault of some sort and not to a station
problem (e.g., RFI). Most are assigned 'G' error codes, but a few were
identified only by looking for anomalous values of (channel fringe amp)/
(coherent fringe amp over channels). All will be reprocessed in the
cleanup pass, along with other error code scans (B, D, and E), missed
scans, short scans, all non-detections, and scans with zero pcal amp
at stations other than Algonquin.
Hobart/Tsukuba: Scattered over the first 5 hours of the observations
there are ~10 scans for which the fringe amp in the lower 3 X channels
is 20-40% lower than the mean amp, and conversely the amp in the
upper 4 X channels is 20-40% higher. All are on either 1741-038 or
1908-201. See email correspondence between Dave Shaffer and Brian Corey
below. Probably a source structure effect.
Fourfitting dates:
DOY 143-144 production pass
DOY 154 repro pass
DOY 167 3 scans with mismatched FRTs + 2 S-band E codes
****************************************************************************
Station Mail:
****************************************************************************
From: GSI VLBI group <gsi32m@gaos.gsi-mc.go.jp>
Date: Wed, 19 Apr 2000 02:04:30 +0900
To: ivs-ops@ivscc.gsfc.nasa.gov
Subject: CA083 ready at Tsukuba32m
Tsukuba32m is ready for CORE-A083.
First source is 1357+769 at 18:00:00(UT).
Sky is cloudy.
Temp:9.67C, Hum:90%, Pres:1013.5hPa
Formatter - GPS = +300 nsec at 18-Apr 16:56(UT).
Tsys: X-band =48.6 K, S-band=67.9 K (EL=90)
SEFD: X-band =290.816 Jy, S-band=362.905 Jy (Virgo-A, AZ=252.2, EL=43.1)
All systems are normal.
Sincerely,
======================================================
GSI VLBI group
Geographical Survey Institute,
Ministry of Construction
Japan
e-mail:gsi32m@gaos.gsi-mc.go.jp
web:http://vldb.gsi-mc.go.jp/sokuchi/vlbi/english/
======================================================
Date: Tue, 18 Apr 2000 19:27:33 +0200 (SAST)
From: HartRAO VLBI Operator <oper@nccs2.hartrao.ac.za>
To: ivs-ops <ivs-ops@ivscc.gsfc.nasa.gov>
Subject: CA083
HartRAO is ready to start CA083.
First source 0637-752 at 17:59:40
Clock offset 18.13 microseconds
MASER late
Weather clear, humidity at heads 35 %
All systems normal
Regards
Ludwig Combrinck
Date: Tue, 18 Apr 2000 17:35:35 +0000 (UTC)
From: oper@blizzard.gcgo.nasa.gov (Gilmore Creek)
To: ivs-ops@ivscc.gsfc.nasa.gov
Subject: ca083, Gilmore Creek, Ready-message
Session ca083 ready message for Gilmore Creek.
----------------------------------------------
Comments:
Fairbanks is ready for ca083 start @ 1800ut.
First source: 1357+769 at 180000 UT
GPS-FMOUT: 7.2 microseconds
Wx: Temperature (C): -4.1 Pressure (mBar): 957.9 Humidity (%): 30.3
Sky Conditions: Clear skies
Cable difference is: longer cable makes the reading smaller by
697 microseconds and is nominal
Pointing values:
SEFD X/S Source Az/El Offset1 Offset2
637/703 cas-a 77/64 .015 .022
538/694 cygnus-a 175/65 .014 .027
Tsys (x1/s/x2): 58/58/51
Recorder Humidity (%): 20
Date: Tue, 18 Apr 2000 17:43:18 +0000 (GMT)
From: Anthony Searle <searle@geod.nrcan.gc.ca>
To: ivs-ops <ivs-ops@ivscc.gsfc.nasa.gov>
Subject: ARO ready for CA083
ARO is ready for CA083, waiting on source 1357+769
SEFDs
3c147 Az = 62.4 el = 51.8 X = 206.9 S = 209.7
3c123 Az = 102.7 el = 54.3 x = 199.7 S = 203.5
Wx:
Overcast skies, light breeze, 4 C, 990.7 mB Humid = 51.9 %
Recorder temp = 23 C Humid = 20%
Formatter - GPS = -1.7345 us
Phase cal is not working
Cheers,
Anthony Searle
Geodetic Survey of Canada
Ottawa, Ontario, Canada
Internet: searle@geod.emr.ca
From: "VLBI - ASI/CGS Matera" <vlbi@asi.it>
To: "ops bb" <ivs-ops@ivscc.gsfc.nasa.gov>
Subject: matera ready for corea 083
Date: Tue, 18 Apr 2000 19:58:24 +0200
Matera is ready for corea 083exp.
We have partially cloudy sky.
Source: Cas-a; Position(a/e): 11/71; Sefd(x/s):1161/1131; Tsys(x/s): 51/78;
regards
G.Nicoletti
Matera Vlbi Team
Date: Tue, 18 Apr 2000 17:59:40 +0000 (UTC)
From: oper@blizzard.gcgo.nasa.gov (Gilmore Creek)
To: ivs-ops@ivscc.gsfc.nasa.gov
Subject: ca083, Gilmore Creek, Autostart-message
Session ca083 ready message for Gilmore Creek.
----------------------------------------------
Started recording with source: 1357+769 at 109.17:59:40 UT
From: "VLBI - ASI/CGS Matera" <vlbi@asi.it>
To: "ops bb" <ivs-ops@ivscc.gsfc.nasa.gov>
Subject: matera started corea83
Date: Tue, 18 Apr 2000 20:00:15 +0200
Matera started on time corea 83 experiment
Gps-Mark IV=16.8 usec
The recorder humidity is 38%
regards
G.Nicoletti
Matera Vlbi Team
From: GSI VLBI group <gsi32m@gaos.gsi-mc.go.jp>
Date: Wed, 19 Apr 2000 03:03:36 +0900
To: ivs-ops@ivscc.gsfc.nasa.gov
Subject: CA083 start at Tsukuba32m
Tsukuba32m started CORE-A083 on time.
First source is 1357+769.
Sky is cloudy.
Temp:7.90C, Hum:96%, Pres:1013.2hPa
Formatter - GPS = 310 nsec at 18-Apr 18:01(UT).
All systems are normal.
Sincerely,
======================================================
GSI VLBI group
Geographical Survey Institute,
Ministry of Construction
Japan
e-mail:gsi32m@gaos.gsi-mc.go.jp
web:http://vldb.gsi-mc.go.jp/sokuchi/vlbi/english/
======================================================
Date: Wed, 19 Apr 2000 04:14:13 +1000 (EST)
From: David Legge <dr_legge@kerr.phys.utas.edu.au>
Subject: Hobart has started experiment CA083
Hobart has started experiment CA083
-------------------------------------------------------------
The first scheduled source was 0637-752 @ 175940/109 UT/DOY
Formatter (H-maser) leads GPS 37.9 microsec @ 1805/109 UT/DOY
Cable Cal 779.0 microsec, shorter cable gives longer delay
Tape recorder humidity 27 % relative at experiment start
Weather and Sky: cool, 15 % cloud, 9 km/h wind at expt start
Comments/Problems: none to report
Regards,
David Legge
Date: Wed, 19 Apr 2000 18:02:41 +0000 (UTC)
From: oper@blizzard.gcgo.nasa.gov (Gilmore Creek)
To: ivs-ops@ivscc.gsfc.nasa.gov
Subject: ca083, Gilmore Creek, Stop-message
Session ca083 stop message for Gilmore Creek.
---------------------------------------------
Comments:
Fairbanks ends ca083 @ 1750ut. Missed 10 scans, from
2040 thru 2118ut due to tracking computer display
failure.
Tape: mailed to Haystack
File: put in apr00
Problem scans:
Source Scan start Explanation of problem
0003-066 2040 failure first source
2234+282 2116 failure last source
Tape Inventory: 5 thin 0 thick
Observation finished at: 1750 UT
From: "VLBI - ASI/CGS Matera" <vlbi@asi.it>
To: "ops bb" <ivs-ops@ivscc.gsfc.nasa.gov>
Subject: Core-A 83 end
Date: Wed, 19 Apr 2000 20:13:28 +0200
Matera station completed Core-A 83 without problems
Start up measured delta time was Gps - MK IV = 16,80usec
Completion delta time was Gps - MK IV = 17,08 usec
Log file stored at CDDISA
Tape label is OVLB0193,A01D
The recorder humidity was 38% at start up; it was 35% at completion time
Matera Vlbi Team
From: GSI VLBI group <gsi32m@gaos.gsi-mc.go.jp>
Date: Thu, 20 Apr 2000 03:24:33 +0900
To: ivs-ops@ivscc.gsfc.nasa.gov
Subject: CA083 finished at Tsukuba32m
Tsukuba32m finished CORE-A083.
All scans recorded.
Sky is rainy.
Temp:10.34C, Hum:91%, Pres:1012.3hPa
Formatter - GPS = 310 nsec at 110-18:23
Tsys : X=63.9 K S=73.0 K (at El=90)
SEFD : X=344.595 S=366.043 (at cygnus-a Az 69.2 El 58.7 )
We put the file "ca083ts.log" on vlbigeo@cddisa.gsfc.nasa.gov/apr00.
======================================================
GSI VLBI group
Geographical Survey Institute,
Ministry of Construction
Japan
e-mail:gsi32m@gaos.gsi-mc.go.jp
web:http://vldb.gsi-mc.go.jp/sokuchi/vlbi/english/
======================================================
From: Steve Farley <farley@geod.nrcan.gc.ca>
Subject: ARO has ended ca083
To: ivs-ops@ivscc.gsfc.nasa.gov (ops)
Date: Wed, 19 Apr 2000 18:26:37 GMT
Algonquin has ended ca083, all sources observed.
Formatter - gps = -1.755 us
Sefd on 3c123 Az = 118.6 El = 63.5 X = 176.1 S = 204.7
Current weather is overcast with light winds, temp is 7.3 c, press is 988.7, humidity is 86.5
Tape drive is at 23 c and 23 %
Tapes will be shipped Thursday April 20.
Phase cal was not working for this experiment, cable length do not appeear to be
correct(related problem)
Log files will be down loaded to cddisa later today.
Regards from the crew at ARO.
--
Stephen Farley
Geodetic Survey of Canada
Ottawa, Ontario, Canada
Internet: farley@geod.emr.ca
Date: Thu, 20 Apr 2000 06:48:48 +1000 (EST)
From: Lincoln Hanslow <lhanslow@kerr.phys.utas.edu.au>
Subject: Hobart has completed CA083
Hobart has completed experiment ca083.
--------------------------------------------------------------------
The PCFS log file has been put in directory apr00 on host cddisa.
------------------------------------------------
Tape Label UT start UT stop
IRAM0148,FB9A 1800/109 0848/110
HS002820,8719 0857/110 1752/110
------------------------------------------------
Formatter (H-maser) leads GPS 37.0 microsec @ 1815/110 UT/DOY.
Cable Cal 724.2 microsec longer delay.
Tape recorder humidity less than 20% relative at experiment end.
Weather and Sky:partly overcast, fine, calm, and cool
Comments/Problems:Parity errors a little high from about 1000/110UT
onwards. Interference in VC14 as usual.
Regards,
Lincoln Hanslow.
Date: Wed, 19 Apr 2000 18:17:24 -0400
From: Stephen Farley <farley@geod.nrcan.gc.ca>
To: ops <ivs-ops@ivscc.gsfc.nasa.gov>
Subject: Tapes for ca083
Tapes for ca083 should leave Ottawa on Thursday April 20, via FedEX
going to Haystack Obs.
Two tapes s0000027, fca6 and ngs00315, 8ae2
Logfiles have been placed on cddisa/apr00
Have a good night.
Stephen
===========================================================
Stephen Farley Email farley@geod.nrcan.gc.ca
Geodetic Survey Phone (613) 992-2236
Natural Resources Canada
Date: Thu, 20 Apr 2000 08:55:45 +0200 (SAST)
From: HartRAO VLBI Operator <oper@nccs2.hartrao.ac.za>
To: ivs-ops <ivs-ops@ivscc.gsfc.nasa.gov>
Subject: Complete ca083
HartRAO has completed ca083 with out any problems.
Weather clear.
Clock offset =18.48microsecs (MASER LATE)
All systems were normal.
Regards
VLBI Team
From bec Thu Jun 15 15:40:30 EDT 2000
From: Brian Corey <bec>
Subject: weird sources
To: dbs@gemini.gsfc.nasa.gov (Dave Shaffer)
Date: Thu, 15 Jun 2000 15:40:30 EDT
Hi Dave,
What do you know about 1741-038 and 1908-201?
In both CA082 (March 2000) and CA083 (April 2000), there is a strong
frequency dependence to the Hobart/Tsukuba X-band fringe amplitudes
on those two sources that is opposite to normal, i.e., the amplitudes
roll off as you go down in frequency, not up. The table below gives
the details on the 2 sources and on 2121+053 for comparison.
Is it conceivable that the weaker amplitudes below ~8.6 GHz are
a source structure effect??
I am reluctant to attribute it to source structure, particularly since
the effect shows up on *two* sources on the same baseline around the
same time. But I'm having a hard time coming up with an alternative
explanation. So before I expend more effort searching for instrumental
explanations, I wanted to run the evidence by you.
Incidentally...
- No other baselines to Tsukuba on the 2 sources show the rolloff, but
then none of those observations is simultaneous with Hobart/Tsukuba.
- The single other baseline/scan to Hobart on the 2 sources shows
no rolloff.
- Phase cal amplitudes at both stations are nearly identical on
all sources. ==> It's not a Tsys effect.
- I see nothing unusual in the fringe plots other than the rolloff.
Given that IF1 feeds channels 1-4 and IF3 feeds 5-8, I would be
suspicious of a problem in IF1, but even within each group (1-4 and
5-8), the rolloff is evident and is contrary to the normal pattern.
--Brian
# Hobart/Tsukuba X-band channel fringe amps for 3 sources in CA083
#
# amp = 1.e5 * coherent fringe amplitude over all 8 channels
# ampn = 1.e5 * fringe amplitude in X-band channel n
#
#DDD HH MM SNR amp amp1 amp2 amp3 amp4 amp5 amp6 amp7 amp8 source
109 18 49 61.7 151 87 100 123 155 177 188 186 196 1741-038
109 19 38 63.0 154 100 106 111 146 170 189 193 222 1741-038
109 20 22 60.4 148 93 104 116 133 180 187 183 192 1741-038
109 21 08 58.7 143 95 99 110 147 171 181 174 173 1741-038
109 22 17 54.6 132 97 99 93 122 158 168 177 144 1741-038
109 18 44 35.8 130 110 108 121 136 143 150 128 152 1908-201
109 19 34 33.5 118 100 98 110 116 124 137 121 151 1908-201
109 20 19 36.3 127 108 105 109 123 148 136 154 134 1908-201
109 21 21 34.2 119 116 117 111 104 142 134 125 111 1908-201
109 23 58 30.6 105 93 93 89 114 109 123 115 108 1908-201
110 16 28 27.2 103 75 81 97 103 110 123 124 112 1908-201
109 18 23 126.8 480 527 518 497 509 492 466 444 393 2121+053
109 19 11 134.5 507 538 546 516 534 514 507 429 473 2121+053
109 19 53 136.5 512 540 533 530 537 518 490 472 481 2121+053
109 20 32 139.3 525 521 594 561 552 541 524 445 463 2121+053
109 21 14 148.8 564 590 603 592 576 578 544 518 513 2121+053
109 21 54 143.9 541 565 574 578 570 535 537 473 506 2121+053
109 22 31 144.9 548 581 579 578 565 559 521 498 511 2121+053
109 23 03 145.8 553 600 576 584 550 564 528 512 521 2121+053
109 23 47 142.4 537 557 575 565 557 525 534 484 502 2121+053
110 21 00 140.3 528 540 570 575 525 514 517 480 509 2121+053
110 57 00 131.4 506 531 538 525 519 508 487 455 484 2121+053
110 01 33 122.4 465 526 507 508 462 467 465 414 378 2121+053
110 02 08 120.9 456 483 492 468 469 476 459 422 385 2121+053
110 16 54 100.3 376 409 404 412 396 362 344 324 363 2121+053
110 17 38 95.1 360 421 393 388 367 364 344 319 291 2121+053
Date: Thu, 15 Jun 2000 18:27:49 -0400 (EDT)
From: Dave Shaffer <dbs@gemini.gsfc.nasa.gov>
To: bec@haystack.mit.edu, dbs@gemini.gsfc.nasa.gov
Subject: Re: weird sources
Brian,
I would not be surprised if you are seeing source structure effects.
I will have to look at the actual fringe amp data, perhaps with
some augmented model-fitting capability, to tell for sure.
However, the models for both of these sources are extended, in
position angle 178 for 1741-038 and PA 172 for 1908-201. (See the
latest source.cat used for SKED.) These PAs result from single
component fits (i.e. to an elliptical model), but I wouldn't be
surprised at nearly-equal double models (in the same PA). Since I
use only amplitudes and not phases for my model fitting, I can not
tell up from down (or left from right) in my source models. I
therefore constrain myself to assigning a PA in the range from 0 to
180 for all sources.
The (u,v) track for the Hobart-Tsukuba baseline for all three of
these sources (i.e. including 2121+053) (and any others at these
decs, too, of course) covers only a very narrow range of position
angles in the vicinity of 0 (or 180, which you can't differentiate
without phases, as noted above!). Thus, the (u,v) coverage is
where one might most expect to see structure effects.
The other thing to note from the model catalog is the relative
strength of the sources. The total flux density in 1741-038 is
about 4 Jy, and 1908-201 has about 2.8 Jy, versus only about 1.5 Jy
for 2121+053, yet the fringe amplitudes for 2121+053 are MUCH
bigger than for 1741-038 or 1908-201.
Thus, I suspect we are observing close to a structure minimum for
the two "weird" sources. A quick hand plot of the amplitudes for
1741-038 versus frequency is not a bad eyeball fit for the case
where the line of first minimum for an equal double source falls
just interior (i.e. closer to the origin of the (u,v)-plane) to the
observing paths (i.e. the multiple (u,v)-tracks which result from
the BWS sequence).
I'll check some old data, as well as the CORE-A82 and -83 data when
they are available, to try to solidify this interpretation.
Unless you get a different story from me then, it's probably not
worth your while to try to track down any other causes!
Dave