2005

Feb 28
Three crates transported to summit. Cryostat crate opened and contents examined and raised.

Mar 01
Today we unpacked the final crate. All was well.
The cradle was put together and the cryostat was "hung".
The american power supply was fitted into the PC.
The daq card was put back into the PC.
Spare monitors, keyboards, mice were identified for the PCs use.
GE varnish and ethanol supplies have been found. Essential for replacing our filters after alignment.
Further converstaions on Helium transfers took place. It seems as if it is quite likely that we will use the JACs rigid transfer line.
Minor (expected) fix up of thermometry/illuminator was performed. All thermometry is working.
The OVC was sealed and the cryostat is now on the pump.

Mar 02
Today was pretty good, the leak check was fine. No leaks.
Electronic checks were completed:

• we (still) have fully working thermometry,
• the tests with the dummy detectors showed that all wiring from the signal port to the JFET box and feedback resistors is intact and that it is all behaving within spec.,

Mar 03
The THUMPER internal alignment has been completed.
It's fair to say that Darren and I are in a state of shock.
Things have been progressing rather well up until this point, no trouble with the altitude (bar tiredness), helpful JAC staff (bar none) and a smooth first couple of days re-assembling THUMPER.
We came to do the alignment of the detector block and cold mirrors with high hopes. There has been a lot of too'ing and fro'ing to make absolutely sure that we operated within the JACs safety requirements. A lot of planning to make sure that we adhered to a strict procedure that minimised the risk to all JAC staff and ourselves. Maybe its the altitude playing tricks on our minds, but something seems amiss. The alignment was a sinch, and the close up from that stage has been the smoothest yet.
We had all lids on by 15:00 and THUMPER has been on the pump with a fully cracked valve since 16:00.
This gives us tomorrow to get all test equipment together and tidy up any loose ends for the tests next week.
We still intend to put LiN2 in on Sunday evening ready for LiHe transfer on Monday morning.

Mar 07
General housekeeping and tidying up of connectors have taken place the past two work days.
The Lakeshore thermometer has been rigged so that a reading is taken every 60 seconds, dumped in a txt file and then plotted in excel. This shall be handy for the LiHe transfer, and when warming up the JFETs.

Mar 08
Today we transfered Helium to THUMPER.
It took thirty minutes! From the start to finish. Thats from BEFORE the line was put into the dewar, to when THUMPER was full!
It was actually easier to transfer up here, the lack of vapour during the transfer made it pretty easy to spot the plume when THUMPER was full. We used the transfer line that was lent by JAC staff. It could have been custom made, a perfect fit which was half the battle.
So THUMPER was cold before lunch. We let it settle down for a bit then did a quick check. All detectors are behaving as expected.
We plugged THUMPER into our flow meter, pondered over the increased boil off before realising that the flow meter is only calibrated at sea level pressure! We'll figure a conversion factor tomorrow.
We'll perform full system checks tomorrow. Things appear to be in the same shape as before we shipped, we'll know definitively soon.

Mar 10
(this from Derek in Cardiff :)
On the home front: The lenses are made and are performing excellently. Combined throughput through the 2 of them is 70%. One in particular is apparently as near perfection as you're ever likely to see (quote) and the other is as near perfect as makes no difference (a few mm off in exact focal length requiring a few mm movement of thumper - no prob since we haven't drilled the holes in the mount yet!). Huge thanks to Brian for learning how to do this from a standing start and producing a superhuman result! Today: Brian is manufacturing the mounts as we speak. Thanks also to the workshop staff for stepping in to help, and to Rhodri for re-directing extra workshop effort our way to make sure the mounts are ready by the end of today so I can carry them out tomorrow.
(later) : I have the lenses and lens mounts in my briefcase . . .

Mar 14
( from Derek at HP :) Spent morning drilling holes in the thumper alignment plate and the lens2 mount, topping up (1) (2) (3) (4) (5) thumper and performing full system checks. One minor fault with battery connection was fixed, and strengthened to prevent a repeat of the fault. This afternoon we winched the FTS optical bench into position on the nasmyth platform (1) (2) (3) and aligned it. Then we winched thumper (1) (2) (3 - What are The New Village People doing here ?) (4) (5) (6) into place on its alignment plate on top of the optical table. Everything went like clockwork, the optic axis matched up, the cryostat fitted on the table, everything sat nicely on-axis. Fitted like a glove straight of the box. By this time it was 4pm and we had to come down. Tomorrow we align the lenses and hook up the electronics through the scuba daq.

David was duly impressed by the lens mounts and the ease with which they meshed with his system. Thanks again Brian!

On the home front: Thank you to Phil & Paul for supplying our new alignment instructions. They look sufficiently detailed for us to follow them at altitude as requested. And Matt has calculated the planetary fluxes so that when we get on sky we'll be able to have a stab at the calibration.

Meantime the storm conditions have returned, bringing 70mph winds to the summit. This made it entertaining even getting out of the car on the ridge at lunchtime. None of the telescopes were open last night, and the forecast is for 100mph tonight. The next few days do not look promising. Hopefully it might improve next week. Yesterday's nice weather seemed to be a blip.

Mar 15
( from Derek :) Thumper is now aligned on the optical table and aligned to the telescope, along with both lenses. The only thing we can't check is the absolute focus until we're on-sky. But David set up his alignment laser and hit the smu dead centre at the first try. Then we aligned thumper to that and also hit the smu dead centre. All dead reckoning is good to a mm or so, and the only way to improve it will be to focus on a source on sky. The step by step instructions from Phil & Paul were excellent - thanks guys!

Also today we installed the cable to connect thumper to the scuba daq interface box.

Mar 16
We powered Thumper up on the Nasmyth for the first time, in standalone mode, using our own pc. We switched on the illuminator and obtained signals successfully from all seven channels . James also fixed up the battery charger to essentially automate the system.

We also ran up the scuba software and passed dummy thumper files all the way from the scuba daq through the surf system and all worked fine. Many thanks to Iain and especially also to Firmin for videconning in from Hilo to make all of that process work for us.

We passed Thumper signals successfully from all seven channels through our cable connection without measurable losses or increased noise. We had one minor glitch at the end of the day at the interface between our system and the scuba daq. After discussions with folk at sea level we are confident now this evening that we can fix this problem first thing in the morning, at which stage we should be ready for whenever the weather breaks. All telescopes are open tonight and the high winds have dropped. As long as the snow and ice remain on the summit freezing out the water vapour we should be in with a chance. Our thanks once again to the JCMT staff, who have all been very helpful.

Mar 17
A major milestone was achieved with Thumper today. We used the internal illuminator to send a modulated signal through the Thumper detectors, right through the signal chain to the scuba daq and read out the resultant data into surf, which successfully analysed the data. Thus we have a fully functioning system. We are hoping to try for first light during tomorrow morning daytime on Mars - 2 full days ahead of schedule.

Well done to James and Darren for a job well done, and thankyou to David for invaluable assistance.

Mar 18

Thumper was ready to observe 2 days ahead of schedule, so after 2nd shift at 9.30 this morning we prepared to carry out observations of the 200-um sky as a first step towards calibrating the sky opacity. The cso-tau was 0.107 so definitely not Thumper astronomical observing weather.

We used the old chopper (1) (2) (3) (4) from UKT14 (yes, really - David had kept it all these years in his cupboard!) to initially chop between echosorb at ambient temperature and Thumper's own 77K stage. We recorded the signal from all channels. We then removed the echosorb and chopped between sky at zenith and the Thumper 77K stage and again recorded all 7 channels. We then repeated the experiment at elevations of 80, 70, 60 & 30 degrees. From these measurements we have a first estimate of the focal plane flatfield, and also a first handle on the relative opacities at 225GHz and 200um.

Mar 19

The THUMPER team went snorkelling : pictures pending !

Mar 20

Today we carried out more chopper tests for calibration purposes. We also moved thumper to its optimal focus position by dead reckoning. Subsequently we re-checked the alignment, and once again hit the smu dead centre. This time we also tested the alignment at all elevations down to 30 degrees and the alignment remained true. We clamped the plate in the correct position, so that when thumper needs a helium fill it should go back exactly aligned.

Thank you to Rashmi for sending the new pc card. That was also installed today and the pc can now control everything standalone if it needs to.

Mar 21

To celebrate the vernal equinox we had another night of cloud. Cleared about 9am. Did some dummy observations after it cleared which turned out to be useful in ironing out remaining software bugs in surf. The water vapour ensured the observations would not be useful for any more than that.

During the night we had carried out some hot and cold load measurements, and calculated a preliminary value for thumper's sensitivity.

We also carried out some tests with the echosorb lollipop to convince ourselves that the 200-um axis was perfectly aligned to the laser optical axis and found to our satisfaction that it is. Thumper illuminates the central section of the tmu, with no overspill. All very reassuring. Thanks again to Phil for the useful suggestions.

Looking at the satellite picture this good weather spell is set to last for the remainder of our run. We just need the humidity to drop. Maybe tomorrow!

Mar 22

Weather did not co-operate. Ran ddt queue observing.

Mar 23

Tau appeared to be dropping, so we attempted Jupiter. No detection. Attempted moon. No detection. tau was actually 0.083, so too high to expect anything really. Reverted to running ddt queue.

THUMPER has been powered down and still remains on the optical bench. It shall remain cold over the next couple of weeks with the JAC support staff kindly topping up LiN2 everyday. A LiHe top up will happen next week (by THUMPER people).

Mar 28

Beach leave was cancelled today so that Helium could be topped up.

With the help of John Pascual, and the Dewar hanging from a crane we managed to fill THUMPER up while it was still sitting on the optical bench. (There is no photographic evidence of this fill...)

We originally planned to take THUMPER off the bench for this, but ZEUS guys have been working in the receiver cabin, and we need to tilt the telescope to get THUMPER off.

The Helium should see us until the end of the run (09/04/2005).

THUMPER is passively boiling off ~0.25 L of LiHe per day. This rises to about 0.4 L per day when JFETs are powered up.

Back to the beach

James

Apr 01

Neal Potter arrives in Hilo, is briefed re Safety and travels to HP.

Apr 06

Possible detection of Jupiter (scuba daq caused problems). Detected Mars using standalone system. Also detection of sun. Did a sky dip and saw a nice difference in values across this. Peter and Darren claim this agrees with their model (well they would, wouldn't they!)

Apr 07

Tau was too high.

Apr 08

Continuing problems with interface to scuba daq. Jupiter was transiting in first shift, so by the time we got onto it we were looking through 1.5 airmass and a Tau_225 of 0.052. Did not make a detection. Made faster sky dip measurements by using just one channel and lockin amplifier. Chopped Mars/sky sky/sky while Mars was transiting. Tau was too high to make a detection. Detected sun through Tau_225 0.056 and 1.68 AM. Followed through to end of shift (forty minutes).

Apr 09

Tau was too high (0.067) to detect Jupiter. Measured sky noise though. Repeated sky dips. Tried observing Mars again through tau of 0.044. Sky noise very high. More sky dips; followed the Sun for fifteen minutes.

Now we need to sit down and take a good hard look at the data. There's certainly something to publish. I'll give a group meeting talk on it at some point soon.

Derek's summary

• We have a working system that's been fully field-tested

• The model transmission seems to be confirmed with the data

• We've shown that 200-um astronomy can be done from the ground

Well done to all concerned, and especially thanks to James who has spent most of the last 2 months at HP! And to Darren who spent a month at HP.

Thumper Home Page at JCMT