GB review : deadline approaches

July 27, 2009

Like many others, I got an email this week with a link to notes from the Ground Based review Town Meeting. You can find this linked at the official GBFR page.  There is nothing very unexpected from that debate, but Michael Rowan-Robinson stressed that we should all pitch in. At the time of the town meeting, there were 95 responses. To make the powers that be pay attention, MRR says we need at least 400, similar to the number that responded to the Ward panel. I know some of you may be thinking “what difference does it make ?” but unless there is a large response, there will be every justification for thinking that ground based facilities don’t matter very much. So get your response in !

The panel have also made it clear that they can accept unsolicited papers, as long as these are within two pages. General rants won’t help at all, but if you have a specific proposal, make sure its known.

MRR also noted that somehow we have to make our economic impact case. In various places, senior STFC folk have made it clear that “the case for space” is made, and indeed there has been a fair amount of PR recently about space and the UK economy and the new Harwell ESA centre, and indeed a consultation has been launched. It seems a bit rough to split off “astronomy in space” from other astronomy, as astronomy overall could have made a good economic impact case. Note however that most of the space industry is not about astronomy, so if space-based astronomy gets bundled up, thats good. But the lesson is that we can’t allow “astronomy on the ground” to be forced into an unfunable ghetto. Must be some trick here we haven’t thought of.

Gnuplot calculator

July 27, 2009

A few weeks back I wrote a post on calculators, expressing my desire for something that was more than a push-button emulator, and less than a full programming language. Something where you just have a window  where you can type 2.3*Msun*c**2, define short expressions for re-use, etc. Python seems to be the obvious thing but it has some annoying quirks; I also recommended Plaincalc. The comment stream was fascinating and very educational, with pointers to Wolfram Alpha, the Statusbar calculator for Firefox, and iCosmo, as well as some Python tutorial from Ross C.

I have been thinking about a similar post on graph plotters. While playing with these, I suddenly realised that the plotting package I use most often, gnuplot, does exactly whats needed ! Doh ! You can do calculations – eg print 18.3 * 27.6. You can define and use variables – eg a=pi/6, b=18.3, and then c=b**2*sin(1.3*a).  You can define and use single expression functions – e.g. f1(a,b,x)=a*x**2+b*sin(x)/x;  then with a and b already set you can calculate g=f1(a,b,2.3)/f1(a,b,3.2). Finally of course you can plot f1(a,b,x) – gnuplot assumes x is the variable and other variables are parameters. Then you can change the values of a and b and replot.

So now I have a file of physics and astro constants which is loaded by my .gnuplot initialisation file, so I can type 2.3*Msun*c**2. Next up, some standard functions, eg RBB(nu,T) = (2.*pi/c**2) * nu**3  / (exp(h*nu/(k*T)) – 1.).

So gnuplot is now my standard calculator, rather than Python interactive mode. The Python fans will now tell me that there is a Python version of gnuplot. Indeedy… but thats straying into the graph plotter shoot-out territory…. Watch this space.