30th January 1995

From Michael Ashley.....

Dear Reader,

Today's diary contains a fair bit of technical details about IRPS, for the benefit of our collaborators who need to know this information.

John was up early and headed straight out to the Pomerantz Building to start taking the IRPS dewar apart. I joined him later and we successfully installed a short-pass filter in one of the aperture wheels by glueing it in with Stycast (a cryogenic epoxy; here is a useful hint c/- Bob Pernic: if you don't want your epoxy to set immediately, just put it outside in the -37C conditions, and it will stay soft for 3 days). John had to grind the edges of the filter on a grinding stone to allow it to fit in the available space. We then replaced the L filter with our new K' filter, and started baking the molecular sieve (8 hours at 450F, or until golden brown). I designed a safety plug to stop the Taylor-Wharton dewar from going soft when left outside (the problem is that its vacuum jacket has a nitrile o-ring, which is only good to -40C).

Aside: the reason for installing a short-pass filter is to act as an additional blocking-filter for the CVF. This should give us a factor of 1000 times reduction in any residual long-wavelength radiation that makes it through the CVF, and will allow us to have more confidence in our measurements of the extremely low flux at 2.35 microns from the Antarctic sky.

John has an annoying habit of popping bubble-wrap bubbles at random times. He claims it is important work, and that someone has to do it. The big bubbles make a sound a bit like an exploding capacitor. There is a moratorium on doing this during particularly delicate dewar operations, or when poised with a multimeter lead just about to make contact with a component. While waiting for the Stycast to set we investigated a problem that we

found yesterday with the stepper motor controller: it mysteriously re-enables the power to the motors when it shouldn't. John poured over the schematics and compared them with the controller hardware - everything looked OK, and then he discovered that by touching a probe to one of the 74LS244 outputs, he could re-enable a stepper motor, and yet the 74LS244 could source/sink 15mA without problems. Something strange is going on, we will have to investigate further with an oscilloscope after dinner.

At 2pm John takes the first exposure of his planned 8-part series, showing how the sun moves around the sky at the South Pole. He gets in another exposure at 5pm, but then it starts snowing.

Tonight's desert was a nice cake decorated with Oreos. Oreos are a simple biscuit (two brown disks separated by a white disk), and are something of an American institution. Non-American's are mystified by the popularity of Oreos since they are only marginally edible, and quite inferior to TimTams, Montes, Gaitys, or in fact any Australian biscuit. Jamie is convinced that several tonnes of Oreos were delivered to the South Pole in the 1970s, and we are still getting though them. The winterovers had a raging discussion the other night about whether there are 45 or 46 Oreos in a packet (apparently both numbers have been measured). As far as I'm concerned one Oreo is one too many.

Incidentally, John wants to pass on his discovery that low-fat UHT milk tastes infinitely better than full-cream UHT milk, though neither approximates real milk any better than does heatsink compound.

We learn tonight that the weather here at Pole has been the coldest ever recorded (on these days of the year). Today is a bit warmer (-35C) due to fairly thick cirrus.

John is putting the finishing touches to the lyrics of the JACARA song when an argument between ``emacs'' and his terminal results in all the text being lost (i.e., ``emacs'' won). He resorts to pen and paper and finishes the lyrics with 15 minutes to spare. The only quiet place we can find to practise is outside in the snow, so we shiver through the three verses (to the tune of Waltzing Matilda):

The JACARA song
---------------

Once were some astronomers camped in a Jamesway,
Under the clear blue South Pole skies,
And they sang as they watched as they waited for the Herc. to come:
``We reckon that these CARA folk are pretty nice guys''.

Refrain: We are JACARA, we're a little bit like CARA,
Who'll come observing down on the ice?
We think Antarctica's the place to do astronomy,
Who'll come observing here down on the ice?

So we sent down the IRPS, and we put it on the ASTRO block,
We sent down Jamie Lloyd, who really made his mark.
Now you've got Jamie - but we think it's really close to quits, because
We've got Michael Dopita, but you've got Tony Stark.

We tried Kitt Peak and Chile and we found they weren't quite up to scratch,
We went to Siding Spring, but the skies were even greyer.
But when we look up from the ice, we find the air is clear and dry,
And the food is so much better that you get at Mauna Kea.

At the CARA meeting at 7:30pm, Tony Stark sings the CARA song, and then we sing the JACARA song. The CARA folk were very polite about our efforts.

After the meeting, we head back to the Pomerantz Building, and work some more on IRPS. John is very pleased with his efforts, and comments that we ``performed six impossible tasks before breakfast'', and ``completely rebuilt the IRPS through the entrance window''. John is modest as always. Meanwhile, I am finally getting acclimatised to the low oxygen at the Pole, and the full power of my brain is coming on-line, enabling me to do a few man-days of computer programming before retiring at 3am.

When I reach the Jamesway (it seems like home now) I am amazed to discover the air full of twinkling bright dots slowly moving around. This is the phenomenon of ``diamond dust'': micron-sized cylinders of ice which catch the rays of the sun and reflect it without any colour. It is quite unlike snow, and a fascinating thing to see.