The battle between nature and astronomy

June 29, 2009

Today we dragged the kidz up to the Maroon Bells for a healthy hike. The driver of the bus up to the “Wilderness Portal” announced that an aspen grove in a neighbouring valley is the largest single organism on Planet Earth. Apparently there is a rival claim for some kind of  vast fungus in Oregon, but in Colorado they know the truth. Of course astronomers and sci-fi junkies know that the Black Cloud was much bigger.

Lifeforms on a more modest scale can cause problems for astronomy. Snapping shrimp can fake the effect of high energy neutrinos in underwater acoustic detectors. Astronomers from Arizona just hate them pesky squirrels. (Compare this and this .)  Auger apparently had problems with cows using the detectors as scratching posts. (Can’t find a web reference…)

On Friday in Aspen we heard from Brian Schmidt about a new example. The Australian Skymapper project is going very well. Telescope commissioned, camera nearly ready. But whats holding them back is ladybirds. They crawl all over the structure, get inside the optical dome encoders, and poor ole skymapper can’t figure out how to point out of the slit. Gaaaghh.

Of course the old timers will remember the infamous gold spot problem. Some people think it was a purely chemical problem, but I know it was caused by an alien virus that leaked out of Roswell.

Consultation pile-up

June 26, 2009

Got an email today about the consultation being held by the Far Universe Advisory Panel. I find the acronym FUAP somehow unsettling. Its like a pastiche of Dr Johnson. “I say to you sir, FUAP !” Anyhoo. I see the Nichol has set up his own FUAP website in Portsmouth, and the official STFC advisory panels page says “nothing to do with us gov”. Seems any ole fule can set up a wiki these days. Not that Bob Nichol is any ole fule. Force of Nature our Bob.

[Yet another Google advert : it really is easy. Forget twiki and mediawiki and Trac and all that. Just check out Google Sites ]

The consultations are piling up. Just keep filling in those questionnaires, and we will reach astronomical heaven, like the giants of old piling Pelion upon Ossa.

Near University Advisory Panel : blew it. Deadline was June 5th.

Ground Based Facilities Review Town Meeting : July 9th

Far Universe Advisory Panel questionnaire : July 10th

Particle Astrophysics Advisory Panel questionnaire : July 10th

Ground Based Facilities Review questionnaire : July 31st

There is also a website for the Particle Physics Advisory Panel, but it doesn’t seem to have a questionnaire. Somehow, particle physicists just mysteriously know what they are doing. The Nuclear Physics Advisory Panel doesn’t seem to have a website. Maybe they know what they are doing and there is no need for anybody else to know.

Earlier today I bumped into to a member of FUAP, who described the consultation as “our bargain basement version of the decadal survey”. One obvious difference is that our consultations are fixed format questionnaires. (“Do you beat your wife (a) every day (b) once per week or (c) only when necessary ?”). No unsolicited white papers here thank you.

Ludwig and Bertie

June 20, 2009

Over at Cosmic Variance, Julianne listed Twenty Insults from P.G.Wodehouse, and myself and his Colesness joined in.  I have to confess that I find P.G.Wodehouse inexplicably exhilarating. His books are complete and utter light hearted nonsense of no consequence whatsoever; but they are  just perfect. His writing is a perfect jewel. Its like Mozart in ink. The cares of the world drop away, your smile widens, and the world is a good place. Why it works is a mystery. The plots and the jokes are somehow always the same and yet ever fresh.

I always take a Wodehouse with me when I go on an observing run, and sometimes two so I can save one up for when too many long nights have made me depressed and stressed. It always works.

Years ago, I boarded a plane with a very distinguished professorial colleague on the way to La Palma. We got out our respective reading material. Mine was a Bertie and Jeeves. His was a biography of Wittgenstein. He didn’t say anything but looked askance and I knew that he was disappointed and a little shocked that I was reading something so trashy. He knew that I knew.

Forty minutes passed and suddenly he snorted. He turned to me smiling. “OK” he said, “I apologise. I have just discovered that Wittgenstein’s favourite author was P.G.Wodehouse”.

One day if you get me in the pub I will explain the plot of a play a friend of mine once wrote called “Ludwig and Bertie” which features Jeeves, Bertrand Russell, Bertie Wooster, Ludwig Wittgenstein, a library in Cambridge, and a rhinoceros.

Wise Vibrations in Purgatory

June 17, 2009

My sabbatical is nearly over. Midnight approaches and the shadow of teaching looms… Fair Nature’s eye, rise rise again and make perpetual day; or let this hour be but a year, a month, a week, a natural day, that Faustus may repent and save his soul ! The stars move still, time runs, the clock will strike, the Devil will come, and Faustus must be damned !

Err.. oh. Sorry. Got carried away. Luckily, before I am dragged down into the dark, I get to spend a few weeks in Aspen. I suppose this is a kind of inverse of Purgatory. Its achingly beautiful here in Colorado, but expensively chic in Aspen itself. Last night I walked past a building with smoked windows and no sign of anything to buy. The sign said “Franck Muller : Master of Complications”. I thought maybe this was some kind of spooky secret society, but Google later revealed unto me that in fact Franck Muller is a Swiss geezer wot makes fancy watches.

So here at the Center for Zen Physics I am attending a workshop on Wide Fast Deep Surveys of the Future. Like most Aspen workshops its rather loosely organised, but there have been one or two actual talks. One of these was by Roc Cutri, updating us on the status of WISE, the Wide Field Infrared Survey Explorer. This is a MIDEX mission due for launch November this year, which will make a mid-IR survey of the sky. It recently passed its vibration tests. I have often heard about these, but never seen what happens…

Roc showed us a picture of the WISE spacecraft surrounded by a ring of 20 foot tall loudspeakers. He said that big trucks turned up and a gang of roadies set up this giant PA system, loaded up their favourite Led Zeppelin CD, and then ran for cover. Really. Nearly as good as Disaster Area.

Overheated Telescopes

June 11, 2009

Do we have too many telescopes ?

The STFC Ground Based Facilities Review is now well under way. There is an official GBFR web page, including a link to a well written consultation document, and an online questionnaire (did I spell that right ?)  The deadline for responses is July 31st. There is related “Town Meeting” scheduled for July 9th. (Thanks to Peter for spotting my earlier date screw-up).  The panel expects to publish a draft report by October 2nd; this schedule is designed to allow some chance of interaction with the US decadal survey.

Back in the 1990s I was on a PPARC review panel called the Ground Based Telescopes Development Panel (GBTDP).  Everybody referred to it as the  Ground Based Telescopes Destruction Panel. This time round the gloomy talk says the answer is already written : pull out of Gemini, close everything else except ESO membership, and pick ONE of ELT or SKA. Is that too pessimistic ? Is it in fact the right thing to do ? (See also Sarah’s post)

For sure, money is short and prospects poor. On top of STFC’s dodgy CLRC inheritance, we have a dodgy economy, subscriptions fixed in Euros with a falling pound, Research Councils faced with “efficiency savings”, a new Science Minister rumoured to be unconvinced by astronomy, and dark rumours of other problems.  Furthermore, as the consultation document says upfront, there is no doubt we have a somewhat “overheated” ground based programme, for understandable historical reasons. Something has to go or we will look foolish as well as greedy. But it would be equally foolish to swing right through to the doom scenario where we have only ESO and ELT.

After reading the GBFR document, I felt the urge to boil down some of the figures to get the big picture. So here are some bottom line round figures in size order. These are rough ten year costs, even though some things might not have ten year lifetimes. The idea is just for very rough comparison. I have mixed up existing things, current requests, and likely future requests, and have used todays exchange rates.

  • ESO incl ALMA : £212M
  • ELT-UK  £110M
  • SKA-UK : £82M
  • Gemini incl Oxford office : £60M
  • eMERLIN : £24M (could reduce)
  • 90% of UKIRT : £20M
  • LSST-UK (guesstimate to 2020) £20M
  • 55% of JCMT : £14M
  • 33% of WHT+INT : £10M
  • 40% of Liverpool Telescope : £5M
  • SuperWASP :  £4M
  • 8% of Magdalena Ridge : £3M
  • ALMA Reg. Centre : £3M
  • Dark Energy Survey (DES) £2M
  • LOFAR ops share £2M
  • JIVE £1M

Note that the fractions are open public fractions – eg Iain Steele (see comment below after my original version) notes that most of the rest of LT is still for UK astronomers.

One way to group these numbers is :

  • ESO+Gemini=260
  • new big-tickets=210
  • 4m-era legacy = 67
  • small beer = 30

So the legacy+smalls represent 17% of the total. My guess is that they represent very good value for money … but they are our only margin.

Calculators that do what you want

June 7, 2009

I have been on a hunt for the sort of calculator a scientist really wants, and thought I would share some results with youse all. But first let me explain :

I often feel the need for a quick calculation whose complexity is somewhere  between a simple sum and a full blown programme. The sort of thing I have in mind is “how much rest mass energy is in that star ?”, or “what would be the black body luminosity from that object?”. You don’t want to write and compile a C program with loops and so on; but neither do you want to navigate lots of menus and laborious button clickings. You just want to jump in and type 2.3 * Msun * c^2 and get the answer. Or for the second example, something like R=3.28e6 and then T=11000 and then 4*pi*R^2 * BB(R,T); and then T=12000 and repeat. You get the idea.

Unix purists would now explain that you have some of this functionality pre-supplied with bc , and in fact you can do calculations with awk, but these are pretty clunky. These days I do this sort of thing with Python in interactive mode. After firing up Python I load up a short module containing some constants – i.e. I put this file in my PYTHONPATH and type  from astroconst import *.  Then indeed I can just type 2.3 * Msun * c**2. I keep meaning to add some simple functions to address the second type of example, but haven’t gotten round to it. Then I began to wonder the other day whether there are tools out there somewhere that have already done this, so I did a bit of a web crawl. There are gazillions of online and downloadable things that emulate traditional button calculators, some of which have good maths and science-y buttons, but this is not what I was after. There are also web based things for specific purposes – like Ned Wright’s excellent cosmocalc – but again not what I was looking for.

I turned up several very interesting and impressive tools. Give ’em a go.

Plain Calc. Mac only. Plain is the word. When you launch it, there is nothing but an empty white window. Beautiful ! But you can type expressions, create variables and use them, and define one-line functions. The history of what you have done scrolls back up, just like a terminal window. You can save your current worksheet and reload it later; so this way you can save your favourite astro constants etc, and get them back tomorrow. However, what you save and reload is literally the worksheet you were in the middle of, complete with the whole history, whereas what you really want is to simply save the variable and function definitions. So… this app is really fantastic and almost exactly what you want, but … maybe just too plain for some; Mac only; and creating your saved “astro-world” is a bit clunky.

PEMDAS Another Mac App. Similar to Plain Calc but with just a little more GUI-ness, so you can for example see your saved variables at a glance. On the negative side, it doesn’t have user-defined functions. Its at an early stage (0.2.4) so a lot of things could improve… Once its finished its going to cost money – but not much.

Google calculator Now why didn’t I know this before ? In any Google search bar, try typing 3.42*sqrt(13)/(4.2*sin(16)). Even weirder, try G/h. The beast obviously knows some physical constants as well as maths functions. But the “more about calc” link above doesn’t tell you what constants are available….

SpeedCrunch This is available for Windows, Mac, and Linux. Like PEMDAS it combines a plain typing window with GUI elements, but you can switch these on and off. (e.g. you can have it with or without a keypad). It is very nicely designed and easy to use. You can define variables and display their current state. It has an extensive set of built-in constants, but you apply these by clicking on them. They don’t have variable-like names that you can type (e.g. “Msun”).  SpeedCrunch has a very extensive built in function list, but doesn’t have user defined functions, although it seems this is on the to-do list. Like Plain Calc, you can save your session, and when re-loaded you get the whole history. So… this a fantastic app, and is clearly going to get even better, but … its a shame it doesn’t have user-defined functions, and the lack of names for the constants is a niggle.

Python As discussed above, running Python in interpreter mode does pretty much what you want. It comes pre-supplied with Mac and most Linux distros, and is pretty easy to install on Windows.  It has a wide set of functions, you can create variables as you wish, and you can define functions. You can write your own modules with a library of constants or simple functions which you can then use. So thats pretty much everything..  But … there are some useability niggles. (i) Integer division gives the “floor”, i.e. 7/2 gives 3, and 7/9 gives 0. If you really want 7.0/2.0 = 3.5 you have to explicitly put the decimal points in. (ii) Results automatically come with seventeen figs, until a number is too big. So 1.3e7*2.4e9 gives 31200000000000000.0 whereas 1.3e8*2.4e9 gives 3.12e17. If you are writing a module, you can format output however you like, with all that %f stuff etc. But in interpreter mode you are stuck with the default. There doesn’t seem to be a command for “switch to 3 sig figs” or “output everything in exponential notation”. (iii) Python stores reals as integer fractions. This produces some peculiar results. If you define “x=0.3” and then type “x” the interpreter returns 0.29999999999999999. This is all perfectly logical, but like the 7/2 business, the result is that the Python interpreter does not behave like a human would like his/her calculator to behave.

Calc. This is a Linux thing, but is also installable on Mac with Macports or Fink. I haven’t had time to look at this properly yet, but it seems to be a mini-programming language with a syntax pretty much like C and the ability to save and load scripts as well as variables. So it may well be the bees knees, but I couldn’t see an obvious advantage over Python, or a nice tool like Speedcrunch. But may I was just running out of steam.

So, lots of really good things but nothing quite right. Can any Python pundits out there tell me how to fix those interpreter mode niggles ?

Mon ordinateur a ete cassee

June 1, 2009

Lessons I have learned this week. (i) Hold on to your laptop. (ii) Brush up your French. (iii) Never let your kids get hold of your work computer.

I have had emails asking if I am on holiday, as there haven’t been any blog posts recently. Well no, I have been in Strasbourg at the bi-annual IVOA interoperability shindig. Normally this wouldn’t stop me posting, but the first day I was there I dropped my lovely Macbook on the floor and as a result was without email for several days. I did get it fixed at an Apple store while still in Strasbourg, which stretched my Franglais considerably. (“Je crois que le disque dur est completement buggered”). However the automatic restore from my Time Machine failed, so I ended up with OS X 10.5 speaking French and had to figure out which library files to move one by one to recover my app settings and printer drivers and unix-y bits. My Mac was still speaking French in various unexpected circumstances until I took it to the Palo Alto Apple Store Genius Bar where a guru who looked like an enormous biker did some voodoo. He also spotted why my Time Machine restore failed : the name of my hard disc had changed back in February but nobody had told Time Machine as it were. Ah yes. I remember. Number four child (eight years old) borrowed my laptop to play Flash games on some website and when I got it back, my hard disc had been renamed “ererer”. He couldn’t quite remember how he had done this but I thought it was funny so I left it. Hah.

But at least its stopped me getting more depressed about STFC cuts.

Oh and the food was good. Just for Tony ….mmmmmm… Baeckoffe.