From: <brett.reid_at_email.protected>
Date: Tue, 28 Mar 2006 10:16:14 +1000

 ('binary' encoding is not supported, stored as-is)
Here is a report summarising the recent LBA week at Hobart.

Remaining S2 tapes all shipped to Sydney Friday 24/3/06. The V131
experiments were shipped earlier.

Recorder still contains the following data:

hovsi:/data/xraid0_0> ls
chris-test-delete lost+found v131bb-old v181e-2 v182a vt07a1
FringeCheck v131bb v181e v181f v182b

hovsi:/data/xraid0_1> ls
lost+found v193a v195a

hovsi:/data/internal> ls
FringeCheck lost+found pulsar v131bc v183b v195a

I am unsure of arrangements for transferring the required disk data to
Swinburne.

TAC NTP server time was wrong a couple of times during this run. This
meant that the digital recorder time was also wrong. The problem with the
TAC was that it got stuck displaying a message about a huge difference in
time between the GPS time and the TAC PC time. Once the time difference
was great it would cease to update the TAC PC time. The NTP server is
derived from the TAC PC time and not the GPS time. The problem is now
fixed by updating the TAC PC time from the GPS hourly rather than each minute.

The SWEO antenna drives caused problems on a few occasions. On the Friday
afternoon, 8 fuses were blown in succession, causing us to miss Adam
Deller's extra V190 experiment altogether. It will be good to have the
new Baldor AC drives on the antenna for the next VLBI run in May.

The second screw for both X and Y axes on the focus platform receiver
positioner is a success. The receiver can no longer be "wobbled" and the
sag of the receiver plate due to gravity, as elevation decreases, is
believed to be eliminated. Pointing has improved such that the Bruce
scans done were centered. For the moment, receivers should only be
changed while the dish is at the zenith or park in order to ensure that
the 2 screw jacks on the same axis remain synchronised. There has been no
problem with screw jack synchronisation so far.

The 2nd channel X band drop out problems in the November run have been
eliminated with the repairs done by Peter McCulloch to the LNA.

The multifeed receivers noise cal heights have been made stable by the
implementation and improvement of constant current sources supplying the
noise diodes for each band. The un cooled S-band and L-band noise diode
supplies need to be done next.

The multifeed receiver is producing lower Tsys for the bands used in this
run compared to November. We are attributing this to the success in
defogging the windows with heaters. The L band window now needs to be
looked at.

The uncooled s-band receiver polarisation reversal has been corrected.
All polarisations are now confirmed correct.

The S2 transports mostly behaved themselves.

Hobart had a large number of observers compared to other telescopes. It
is a training opportunity for students doing honours and PHD. Organising
the roster was difficult with the time available. We were busy getting
the telescope ready with the completion of the feed translator upgrade
and the reinstallation of the multifeed receiver. There will always be
hardware preparations for the VLBI run. I feel it is better to have
someone on the main campus, who is in touch with the observers available,
to organise the roster and let me know the names and times.

Documentation is recognised as lacking for the observatory. I would
appreciate it if you could make a note of any questions you asked and the
answers you found, if any, and email them to me so I can collate them for
the observatory documentation.

Thanks to everyone for making this a successful run.

Here is a summary of each experiment taken mostly from the FS logs:

VT07a1ho:
40 minutes of data exists from 068/0500 in hovsi:/data/xraid0_0/vt07a1>
This is probably the data when other telescopes were on source and
recording. Other Hobart data for this experiment has probably been deleted.
Setup as per Wiki with 64MHz DAS profile and BG3B cable.
Observers: Brett Reid, Giuseppe Cimo.
The X band tsys was measured later in the run of experiments and found to
be around 450 Jy.

v131bbho
Run went OK.
Transport 0 stopped after first tape change but restarted OK using
transport 0 record
Setup as in Wiki with additional Hobart setup information below.
2nd LO 777 MHz
DAS profile MP16S_N.pro
Observers: Giuseppe, Brett, Cliff

V182bho:
Disk data recorded as well as S2. The data is currently on
hovsi:/data/xraid0_0/v182b>
The disk recorded data includes files named: v182b-Ho_069_140008.lba
through to v182b-Ho_069_200058.lba
Setup was as in the wiki.
Observer comments from the FS log follow:
observer: Cliff Senkbeil
weather: 100% cloud cover, no wind
IF1 is RCP
IF2 is LCP
Centre frequency is 8425 MHz
First LO is 777 MHz
Correction, that's the second LO
Coherence tone 842.2 MHz

v191aho:
ANTAB file contains corrected tsys values according to Jamie's
instructions in the log.
Observers: Jamie McCallum and Sally Long.
Observer comments follow:
2006.070.10:49:13.14;"System temptress and CAL values derived from scans
on 3C161, using a flux density of 12.88 Jy at 2.282 GHz
2006.070.10:50:58.31;"Weather is cool and calm. Thin, total overcast.
2006.070.11:30:36.24;"RCP is channel 1, LCP is channel 2.
2006.070.11:31:47.45;"First LO is effective 2.6 GHz (5.2 GHz fixed,
agilent at 7.8 ghz
2006.070.11:33:33.80;"Second LO is set at 834 MHz, putting 2.282 GHz at
1152 GHz into the frequency translator.
2006.070.11:34:44.16;"Coherence tone is tenth harmonic of 227.9 and
system is coherent.
2006.070.11:55:45.47;"NOTE - Polarisations were incorrectly labeled!
Chris Phillips detected this and notified us before experiment began. All
tape based data should have correct polarisations. From 1154,
polarizations are RCP, LCP
2006.070.11:58:08.78;"Tapes are rolling.
2006.070.12:02:13.63;"One small problem - the CAL values are different
for RCP and LCP. With the switched polarizations, the reported values are
incorrect. To obtain correct value, you need to multiply Tsys1 by 143/110
and Tsys2 by 110/143.
2006.070.12:45:36.70;"Weather is cool and calm. Thin, total overcast
2006.070.14:44:09.49;"System coherent
2006.070.14:46:10.74;"Weather is cool with light winds. Thin total
overcast persists.
2006.070.17:55:51.00;"System coherent
2006.070.17:56:38.50;"Weather is cool, calm and fully overcast (thin haze)

v181eho:
The receiver used for this experiment was s/x geodesy receiver, different
to the last experiment. The cryogenics began to warm in the last 2 hours
after 0700.
Observers Jamie McCallum and Claire Hotan
Observer comments follow:
2006.070.18:51:13.51;"Using the cooled S band receiver of the S/X system
(RCP only). 1st Local oscillator is 2020 MHz. 2nd LO is the SML, set to 904 MHz
2006.070.18:52:19.23;"Using DAS profile VSOP_HO.PRO gives coherence with
a tone of 2257 MHz.
2006.070.18:54:31.54;"Systemp's CAL values were determined by scans on
3C353, using a flux density of 39.49 Jy &#64; 2260 MHz
2006.070.19:23:16.23;"uic dcbias statistics are 50/50/50/50 or uic's 0,1,2,3.
2006.070.22:53:54.56;"Weather: warm, 20% cloud, light breeze
2006.071.02:38:11.39;"New tape set started okay, and 20min disk recording
for fringe test at same time as start of new tapes.
2006.071.04:04:42.57;"Weather: Hot, 60% cloud cover, wind 25km/hr
2006.071.05:33:30.47;"Weather: Hot, breeze 15km/hr, 10% high-level cloud cover
2006.071.07:15:15.41;"Receiver temperatures currently insanely high.
2006.071.07:15:56.73;"Pointing North-West-ish, but at an elevation of
about 45 degrees.
2006.071.07:16:14.54;"The sun is in that direction, but it's closer to
the horizon.
2006.071.07:17:57.40;"Systemp values okay.
2006.071.07:20:18.83;"Weather: hot, 70% cloud cover, smoke on horizons,
breeze 10km/hr.
2006.071.07:47:23.56;"RX values still climbing :(
2006.071.07:53:08.15;"SX receiver has warmed up in the last 2 hours or so.
2006.071.08:32:39.90;"Weather: Warm, light breeze, 100% cloud cover
2006.071.08:33:05.41;"Experiment ended okay apart from receiver warming

v183bho:
setup as per wiki
DAS profile mp16s_n.pro
agilent 10.5 GHz
SML 668 MHz
Coherence tone 481.3. 10th Harmonic produces 5 MHz on tape.
Scan done on Hydra. tsys for channel 1 was measured as 383 Jy
Antab file is correct for 1st channel and values were obtained by scaling
tsys in log by .66 and second channel by 1.26 to correct. Values for the
second channel are less certain and likely to be less.
Observer comments follow:
2006.071.15:06:51.21;"weather log: cloudy, moderate/strong winds
2006.071.15:38:39.42;"scan done on Hydra after fringe test. Scan was good.
2006.071.15:40:25.31;"system temperatures will need to be scaled by the
results from the test scan
2006.071.20:43:50.47;"weather log: heavy rain, low moderate winds
2006.071.22:20:07.02;"weather log: full cloud cover, low wind
2006.071.23:34:32.96;"30% cloud cover, moderate NW wind. Wind was strong
overnight with no wind stows occurring in this experiment.
2006.071.23:35:17.04;"observers: Brett Reid and Matthew Wade
2006.072.02:17:25.53;"50% cloud cover, moderate NW wind
2006.072.08:02:21.07;"weather: cloudy. occasionally some rain
2006.072.10:45:27.93;"weather: overcast
2006.072.13:32:08.90;"wind too strong. Wind stow
Antenna re acquired after wind stow at 072/1340

v193aho:
Hobart setup:SCF 1650 MHz, sml 602 MHz, coherence tone 819.5 MHz, Das
vsop_ho.pro.
15.87 dB attenuation into quadrature hybrid for matched signal levels.
Phase shifting trombone set to 225 steps out from in limit.
Injecting a tone at 1650 MHz into the tone port (LCP) produced a 25 dB
larger tone in LCP IF. i.e. 25 dB channel separation.

There were problems with the antenna drives and the drive PC during this
run. You can grep the log for "acquired" to check when we were on source.
The antenna was on 1921-293 for the first few minutes.
There was an X antenna drives current limit indication problem.
Scan numbers from 0030 to 0033 (0224 - 0229 UT) were missed while fixing
the antenna drives. The antenna drives were not very well behaved in this
experiment prior to fixing the problem.

The HOVSI clock was noticed wrong some time prior to 0949. This was
probably caused by a problem on the NTP server within the new TAC. Jamie
Stevens from Ceduna and Chris Phillips from Mopra both made adjustments
to HOVSI's clock. It was correct after that.

v195aho:
Setup was as in Wiki except DAS profile was MP42_F.pro
Coherence tone of 833 MHz produced a second harmonic of 1666 MHz which
was 1 MHz above LBE to produce 1 MHz on tape.
Channel separation at 1667 was measured as 30 dB.
phase shifter out from in limit by 255 steps
12.06 attenuation at the input to the quadrature hybrid
1667 sky frequency.
Antenna drives were OK for this experiment.
Scan was done on 1934-638 after the experiment. It was centered and tsys
for channel 1 was measured to be 535 Jy. The antenna drives developed a
fault during the second channel calibration and it could not be done.
1 set of tapes

v131bcho:
Run went OK.
It is not expected that the 842.2 MHz tone which was inadvertently left
on for a period will not show in the data since the comb generator
amplifier was off.
Observers: Cliff, Sally, Brett, Jamie M.
setup info as per wiki with following addition info:
Agilent 14 GHz
5.2 front end LO
total 1st LO of 8.8 GHz gives IF to control room of 375 MHz
SML 2nd LO 777 MHz
DAS profile MP16S_N.pro
coherence tone 842.2 produces 5 MHz on tape
scan was done on a source and tsys around 448 measured
2006.074.21:42:50.56;"there was a 842.2 tone on (but not harmonic
generator) on between 074/1511 and 1858 UT.

v181fho:
Experiment went OK.
Observer: Jamie McCallum.
Hobart is used the un cooled S-band receiver for this experiment. The
cooled S band receiver was warm and therefore not used.
DAS profile is VSOP.PRO, not VSOP_HO.PRO as stated in the Wiki. A tone of
225.7 MHz gives coherence on the 1st channel
Effective first LO is 2.6 GHz, from an agilent setting of 7.8 ghz and a
fixed LO of 5.2 GHz.
SML provides second LO of 820 MHz.
Systemp CAL values derived from scans of 3C161, using a flux density of
12.94 Jy &#64; 2.<!--nospam-->268 GHz.
UIC DCBIAS statistics are 50/50/50/50 on 0,1,2,3 as expected.
We are recording RCP. This has been tested using an RCP radiator.

v182aho:
Run went OK.
Setup as in Wiki except as follows:
DAS profile MP16S_N
SML=668
SMY=481.3
Scan done on a source prior to experiment was OK.
Tsys was measured and we attribute the 30% reduction at this frequency to
the steps taken in defogging the dewar window since the last run when
this band was used.

v185dho:
Run went OK.
The CAL values used in the systemp command were obtained by scans on
3C161. There were some problems obtaining these and may be out by ~10%.
setup is as in wiki with following additions:
agilent 7.8 ghz, internal fixed LO 5.2 ghz
IF 320MHz to control room
SML 832 MHz
coherence tone SMY 227.7 MHz produces 5MHz on tape.
DAS profile MP16S_N.pro
observers: Jamie McCallum/Brett Reid

Regards,
Brett

Brett Reid
Observatory Manager, Radio Telescopes
University of Tasmania
School of Mathematics and Physics
phone + 61 3 6248 5285
email brett.reid_at_utas.<!--nospam-->edu.au
web http://www-ra.phys.utas.edu.au/~breid/
Received on 2006-03-28 10:16:57