Archive | June 2012

Installing casacore 1.5.0

Casacore no longer uses the scons system so you have to use cmake (make sure you have a new-ish version).
Dependencies that you probably just can’t get from apt or yum: wcslib
install wcslib
tar -xf wcslib.tar.bz2
cd wcslib-4.13.4
./configure --prefix=/import/apgpu02/sgeorge/wcslib/
make -j4 && make install

now make casacore
cd /import/apgpu02/sgeorge/
tar -xf casacore-1.5.0.tar.bz2
cd casacore-1.5.0
mkdir build
cd build
mkdir /import/apgpu02/sgeorge/casacore1.5/
cmake .. -DMODULE=all -DBLAS_LIBRARIES=/usr/lib64/ -DLAPACK_LIBRARIES=/usr/lib64/ -DREADLINE_LIBRARY=/usr/lib64/ -DFFTW3_LIBRARIES=/usr/lib64/ -DCFITSIO_LIBRARIES=/usr/lib64/ -DCMAKE_INSTALL_PREFIX=/import/apgpu02/sgeorge/casacore1.5/ -DWCSLIB_ROOT_DIR=/import/apgpu02/sgeorge/wcslib/lib -DBUILD_SHARED_LIBS=OFF -DWCSLIB_LIBRARY=/import/apgpu02/sgeorge/wcslib/lib/
make -j4 && make install

Come to ALMA @ the Royal Society SSE

From the 3rd to 8th July 2012 at the Royal Society in London you’ll be able to see some of the most exciting cutting-edge science and technology in the UK. I’m involved in one of the stands this year, helping to write some software to show how radio telescopes work. I’ll be around on the stand from 4th to the morning of the 7th.
The cutting-edge science we are showing of is ALMA – the Atacama Large Millimetre Array. This is an epic telescope consisting of 66 dishes working in a rather inhospitable environment, almost halfway into space. There is a blog [over on tumblr] that I’m helping with – there is some cool ALMA related posts – but much more can be found on the exhibition pages.
We also recorded a couple of videos… which I feature in sounding like a proper Brummie:

Ickworth and Bury St Edmunds

On Sunday I had to go for a suit fitting in Bury St Edmunds and we decided that this was the ideal chance for us to go tick another [National Trust] place off the list (Ickworth this time). That and my internal voice was thinking that’s us getting our full membership worth of visits done, in less than 2 months.
The [National Trust] describe [Ickworth] as “A Georgian Italianate palace in an idyllic English landscape”. Indeed the gardens are quite beautiful and even though it was a bit windy it was a lovely day to walk around the gardens. There was even some bike race going on, we took a quick look at that and I think we were glad we weren’t taking part – looked quite hard going. [Ickworth] House is a Grade I listed building that was created in 1795 by the 4th Earl of Bristol. The main attraction for us was the rotunda building (pictured above), though I have to say – like many of the houses we have gone around I wasn’t so fussed. Elizabeth suggests that this is due to my dislike of being reminded that people have money. She is probably right. When we go around castles and such I can see there being a point to the building. I guess there is still the waste of wealth there too but I find it easy to reconcile than the grand Georgian and Victorian houses. Still I do enjoy taking photographs of the buildings and walking around the lovely and generally huge gardens ([Ickworth] is something like 1,800 acres!).
Bury St Edmunds Abbey ruins
Before we headed to [Ickworth] we took a short walk around Bury St Edmunds, after I had my suit fitted. It turns out that Bury St Edmunds is known for brewing and malting (we even walked passed the Greene King brewery). The Abbey is quite spooky with many large structures still existing after it was mostly destroyed during the 16th century Dissolution of the Monasteries. The Abbey is now mostly a nice looking park and overall the town seemed really quite nice to me. I’d have loved going there as a child given you can really be surrounded by history that looks castle like (see above picture).
We manged to go on the day that there was a massive fire (well the night before) which [destroyed a 17th Century building]:
Bury St Edmunds Fire
Oh and there was also a lovely but small rose garden so I had to take some photos:
Rose Garden at Bury St Edmunds Abbey
More photographs can be found in my of the day.

MRAO: AMI Large Array

As the public outreach officer in the [Cavendish Astrophysics group] at the University of Cambridge its part of my job to [organise tours around the telescope] (the MRAO – [Mullard Radio Astronomy Observatory]) for school groups and scientific interest groups. I’ve recently taken quite a few different groups around, from visitors from afar (Strasbourg and Brussels) to those from just up the road (Kings Lynn AS). I thought it might be a good idea to post some information on some of the telescopes you can see on here with some of the photos I’ve taken as I know its not always possible for groups to get out to the observatory.
So lets get started with AMI – The Arcminute Microkelvin Imager. AMI consists of a pair of interferometric radio telescopes – the Small and Large Arrays – here I’m going to focus on the large array.
AMI Large Array
The Large Array is made up of eight 12.8-metre-diameter. These are all equatorial mounted parabolic antennas and were originally part of the Ryle Telescope. The antennas are separated by distances ranging between 18 and 110 m. This means the telescope has an angular resolution of around 30 arcseconds. The Large Array is used to image radio sources, these are mostly galaxies, that produce contamination in the Small Array observations of the cosmic microwave background, i.e. the telescope has a better resolution so can remove the structure.
AMI Large Array

New Paper: Observations of the magnetic Bp star HR Lup

I have had a [paper accepted for publication] in the [Bulletin of the Astronomical Society of India] on some low-frequency (647, 277 MHz) Giant Metrewave Radio Telescope (GMRT) observations I undertook a few years back. This was quite a satisfying paper to write as it was good to get through some of the data I’ve had sat on disk waiting to be analysed. It was also an interesting dataset, having not previously analysed data in dual mode with the GMRT before. It was nice to be able to do all the processing and imaging in [CASA], which is a first for a paper for me.
In the paper we discuss the observations we undertook of a magnetic chemically peculiar star (HR Lup) and how we didn’t actually detect the source in both an average image (over all channels and all times) and in a time (we constructed images every 30 seconds to the scan length to see if there was a flare in emission). In some ways this was disappointing, a low frequency detection of this kind of object would have been very exciting. Saying that, however, we are now able to put a constraint on the emission mechanism. The null results in our paper provide evidence that an optically thick gyrosynchrotron model is the correct mechanism for the radio emission of HR Lup and this supports previous observations.
f you fancy taking a read of the paper see: [arxiv:1206.1155].
Some of the terms used above might be confusing, if you aren’t familiar I’ve found a few useful resources: for the more advanced reader I’d suggest taking a look at the [Annual Review of Bastian, Benz and Gary (1998)], for others I’d suggest taking a look at the NRAO webpage – they have a great description of the generation of radio waves via many different emission mechanism.

I got up at 4.30 for this…

Clouded out Venus Transit
Yep another astronomical event and another cloudy sky. Thinking back to the numerous events over my life time I swear there has only been two events that has not been really disapointing due to cloud, the [Venus transit in 2004] and [one lunar eclipse in 2007].
There are times I do wonder why I bother getting up for these events. Then again, I was greated by a stunning Moon this morning:
Moon whilst hoping the clouds would go
So, there was some compensation to be had. Now time for some copious amounts of coffee and back to the astrophysics, well coding.

Wicken Fens

Since the weather was a little changeable yesterday we decided that it might be nice to go out to somewhere not too far away. Given we are both [National Trust] members we decided that it was time to visit another of the local places to Cambridge. I have to say I was very pleased we decided to go to the [Wicken Fens] – one of Britain’s oldest nature reserves. We had a lovely walk, albeit a little damp in places, around the Fens (which are mostly boardwalked) seeing lots of colourful dragonflies on the way. It was a great place to spend a few hours on a bank holiday Monday.
I managed to even capture a couple of the dragonflies in action:
Wicken Fen Dragonfly
Wicken Fen Dragonfly
Most of the dragonflies we saw were either Emperor Dragonfly (like the ones above) or Brown Hawkers (the photos I took of this just came out disappointingly blurry).
Apart from the nature there is a great example of a Windpump, which is likely one constructed in 1886 and restored 1956 – though it is no longer works as a pump:
Wicken Fen Windpump
There is lots of hides around the site, so I expect its great for birdwatching too – we saw a couple of birds but nothing spectacular and well I don’t think I could have told you what they were anyway!
Overall a lovely place to visit, somewhere we will go back as there are many longer trails too.