Sunday, 20 March 2011

SD329: Book 1

Book 1 actually contains the first two blocks. That is:
Block 1 - Introduction to the senses 
Block 2 - The sensory nervous system.

The first block is a general introduction to the senses, it goes through the senses in overview and gives a taste of what will be coming up in the course. It coves a number of optical and other illusions that show how our senses can be fooled, a theme that reoccurs throughout the course.

Block 2 is more detailed, and goes into how the nervous system works. From the basic functioning of nerves and neurons, to the sensory apparatus that triggers things like touch and pain. It also covers the general layout of nerves in the body, what goes where, how they are interconnected. Afferent and efferent, which I'm destined to get mixed up through the rest of the course.
It then finishes with a chapter devoted to imaging the brain, which takes us through the basics of EEG, SQUIDS, PET and fMRI.  So Not a bad introduction, and a taste of what's to come.

Friday, 18 March 2011

SXR208: Day 7

Day 7 - wrap up

Nothing special today except for a wrap up meeting in the hotel at 2pm. So a chance to catch up on sleep until then with no project reading to be done. I think by now we were all pretty tired, so the chance of sleeping in until late was good. We ventured out for some breakfast/lunch at about midday, I can't remember what we had.

Then we went to the bar area to meet up for the final briefing. Here we had to get the final details, and also let them know what project we were going to write up.

Finally a photo by the swimming pool - I don't think anyone had ventured into it, but it made a nice foredrop.

I could go on to tell you about the drinks in the local bar that night, the um slightly odd "live" music they had in the bar, and those people who stayed there till 4am and nearly missed their flight, but I won't bother.

Thursday, 17 March 2011

SXR208: Day 6

Day 6 - CMD of clusters

 The last proper lab session tonight - and looking like the skies are clearing too. If so this could be a really good session. We have to look at clusters, two open and one globular. This was our final night and would be assessed from beginning to end.

We started by selecting 3 different choices of nebula, with a couple of backups. We hoped to get M35, M67 and M3. We then worked a plan of observing together with our darks, flats and biases we would need.

We then set about the task of getting the nights images. What cloud there was seemed to be quickly fading and things were looking good.

We took our calibration frames quickly and then searched for a reference star nearby the target to synchronise the telescope to. We had to wait for the cloud to shift, and at the same time the team in the labs were producing finding charts for the object chosen so we'd know it when we found it.

We found our first target and took several images of it, in both the V and V bands using filters for M35.
We were going to try our second open cluster, but to our horror found it was right next to the full moon. So we skipped that one for now and went on to look at the globular cluster, M3.

We got some good images of this, in both bands, and sent them off for analysis by the team in the lab.
We then had our midnight snack, and by now the moon had moved a bit, and we wondered if we might get our final target. It looked a little close, but we gave it a shot, and it worked out OK.

We were then going to try for one of our secondary targets, but the telescope went a little weird, it reset itself and decided it was now midday in 2002 so all our coordinates were off. This despite being equipped with GPS. The course director took a look at it, but decided it couldn't be fixed right now - seemed to be an issue with power sources. Anyway, we had enough data, so we all joined in on the analysis.

After gathering data from lots of selected stars, and plotting them on a graph, we were able to make a reasonable Hertzsprung Russel diagram with a part of the main sequence and the red giant turn off arm. This allowed us to estimate the age of each of the clusters, although our error bars were pretty huge.

However it was a very successful night, and with more data and more processing time we could have got a better estimate. A very positive end to the weeks observing. Back to the hotel and a quick walk on the beach at 5:30 in the morning - it was empty! The skies were a little light polluted too - so we could only see the main constellations, and the moon we'd hoped would be nestling over the water had set. So we all went to bed!

Wednesday, 16 March 2011

SXR208: Day 5

Day 5 -Photometry

After getting up late again - there was breakfast to be found - although it was lunchtime. Later I found some cake and coffee with a friend before starting the trip to the observatory.

Today we'll be looking at some key stars to try and work out how bright they are and what effect the angle ot looking at them has on the amount of light. This is called the light extinction plot, and gives you a simple equation that relates the angle you are looking at the star to the amount of light absorbed at a couple of wavelengths. In this way you can compensate for the angle you're looking at a star for and get a much closer idea of its real magnitude.

We had our planning session and picked two stars that we might go for, despite the weather looking pretty unspectacular.

The night was cloudy so we didn't get any real data, although we went through the usual procedures of setting up and parking the telescope.

We had to look at stars in both B and V bands and do various calculations on them. There was also a lot of work on errors that we had to work through.

We had a good time - but what with the error calculations and cloudy skies it wasn't my favourite investigation, although chatting with the tutor who was a professional astronomer was well worth while.

Tuesday, 15 March 2011

SXR208: Day 4

Day 4 - Spectroscopy

Today we hope to take spectrographic images of stars. It is quite amazing what you can do with a spectrum fo a star. You can work out what its made from, how big it is, which direction it is moving and all sorts of other things, which rather puts the final nail in the quote 
"On the subject of stars, all investigations which are not ultimately reducible to simple visual observations are ... necessarily denied to us. While we can conceive of the possibility of determining their shapes, their sizes, and their motions, we shall never be able by any means to study their chemical composition or their mineralogical structure ... Our knowledge concerning their gaseous envelopes is necessarily limited to their existence, size ... and refractive power, we shall not at all be able to determine their chemical composition or even their density... I regard any notion concerning the true mean temperature of the various stars as forever denied to us."
— Auguste Comte,

Waking up around 11:00, we headed toward the beach in search of food, and found a rather good paella, with lots of sea food in it. The sort that sticks out and looks at you.
Then after reading up on the evenings project, I met with some of my group. Some of the group wanted pre meeting planning to get things ready for the planning meeting. I arrived late, but joined in, and then it was soon time to board the bus. Another talk in the planetarium and then the planning session, where we again identified stars. Then off to get some food - very nice it was all week.

Then to the work in hand. First we had to calibrate the spectrometer. So this was done with a He-Ar lamp which produces a well defined spectrum. We took an image of this and then went off to the lab to make a calibration graph so we would be able to analyse the spectra we were to take.

Then the team I was in went off hunting around the sky for our targets. The first two were nice and easy to find, Arcturus and Regulus. We managed to get these stars onto the diffraction grating slit without too much trouble, but still made a couple of mistakes, but we had time as the clouds drifted by. We stopped for the midnight snack and lots of coffee.

Then it was onto a fainter object, BD+31 2750 - trips off the tongue! Finally Saturn just before the clouds rolled in and we had to stop for the night.

We managed to extract a few spectra, but some of our graphs seemed to be off by about 4nm. Something we couldn't explain despite redoing the calibration. We had a debrief with Andy which went pretty well, we decided we needed more data really. This was our first experience using real data, and we were all quite excited to have done something real.
The bus at 4:30am, and back home to bed at about 5:30 and make sure those do not disturb signs firmly attached.

Monday, 14 March 2011

SXR208: Day 3

Day 3 - Binary Stars
The pressure steps up as today we do real projects, projects that are assessed. We started with a lunch/breakfast at Jaime's. A simple baguette of ham and cheese, but with salad and a fried egg in it - unexpected but yummy!

Today we're doing binary stars, trying to detect the presence of one star orbiting another. The weather looks foul, so I think we'll be working with archive data.
There was an initial talk scheduled, but a power cut at the site put pay to that for a while, but soon power was restored and we got going again.

We first had to have a planning meeting where our team decided on what star to look at from a list of candidates, what exposures and so on.

We first had to process the images, to subtract dark, bias and flats. Then we had to do some comparative photometry. Comparing the target star to a reference star to see if it changed in brightness. A couple of check stars were also included to check that the reference star wasn't varying too.
Luckily Maxim DL does a lot of the hard work for you here.

We then exported the collected data into excel and plotted a graph, and wow, it looked as though we had detected something.

There we have it - clear evidence of a periodic dip in brightness. We then had to go off and do protracted calculations to work out from this the period, and using some other data how massive the two stars were as a result. Pretty impressive stuff.
We then again went through the motions of setting up the telescope and taking the requisite basic images - as, like the tutor said, you need to be quick at doing this, because if you get clear skies tomorrow it will save you time to have practised.

We then finished off our data, and then met up at about 4:00am to discuss it with our tutor. Then home to the hotel and crash out until tomorrow.

Sunday, 13 March 2011

SXR208: Day 2

Day two of the residential, and the first full night scheduled.

Today we get to play with telescopes, and start getting into the rhythm of the course.

It's a bus at 4:30 to get us to the observatory at about 5:30, we then have a talk in the planetarium. Tonight's was about the software we would be using, Maxim DL and excel. How we would be taking bias, flats and dark frames to allow better processing of the science images that we would take later.
Bias frames are a dump of the CCD detector to sense the effect the bias voltage on the chip has, this can then be subtracted from the full images.
Dark frames are exposures taken for the same time as the science frames, but with the shutter closed. This allows an estimation of the thermal noise that would occur on the image, and again can be averaged across several frames and subtracted.
Finally flat frames are images taken on a lit white image (a big round target held up to the telescope lit with a lamp) that allowed for vignetting, dust and other oddities of the optics to be taken into account and subtracted.

We spent the first half of the night in the lab, occasionally looking outside at the clear skies. We did some Maxim and excel processing of data, and my partner for the night and I were both pretty computer literate, we zoomed through the tasks. We finished with over an hour to spare, and the course director suggested that as there was a telescope spare we could have a play with it. We got it all set up and ready to run, and focused on Saturn, when they had a breakdown in one of the other domes, and kicked us out! So close.
Midnight, and after our snack session and quite a lot of strong coffee, it was our legitimate time in the domes. However the sky had clouded over and nothing was visible now. So we went through the motions of setting up the telescope, taking darks, flats and biases, and then went through the shut down procedures for parking the telescope. Then after a bit more time in the lab, we went back to the bus at 4:00am for the ride back to the hotel. There we had to attract attention to get the main door open, and then to bed. Everyone had to remember to hang the "Do not disturb" signs on their door, as no one wanted their room cleaning whilst trying to sleep!

Saturday, 12 March 2011

SXR208: Day 1

Day one of the residential school in Mallorca.

I'd arrived the previous day, an early flight meant getting up even earlier to get to the airport (2am) so it seemed sensible as the first night was scheduled to end after midnight to arrive the previous day and at least get some sleep.

The formal part of the day started with registration at 4pm, and then some sitting around in the bar area waiting for the bus to arrive to take us to the observatory. It's about a 50min journey into the middle of the island, down increasingly tiny roads to get to the observatory. We were about half way there, where the bus broke down. Overheating apparently, but they said there would be a replacement in 20 minutes. Much to everyone's surprise, they were good to their word, and we reached the observatory just 20 mins late.

We arrived in the pouring rain, and the nights scheduled stargazing look like it wasn't going to happen. We split into groups and went for a tour of the site, with coats on in the rain. We got familiar with where the various buildings were and how to get between them, in the dark "No running and use torches" was the mantra drummed into all of us.

We got given our documents, a clipboard, a notebook and a planisphere set for the local longitude. We had a good lunch and then went to the planetarium for a show, and ended with stargazing in the dome, given the inclement weather.

The night ended at about midnight, and the trip back to the hotel, uneventful this time.

Wednesday, 2 March 2011

SXR208: The Preschool assessment

Its nearly time to go to this, its come around quite quickly.

Before you can go though, you have to complete a pre school assessment. This is based on the text book provided with the course, and consists of an online test with, in this case, 28 questions.
I thought the questions might be quite easy, but I struggled to answer more than a couple without referring back to the book.
It has questions on the following
  • Positional Astronomy (5) - this is things like right acension and declination, local zeniths and so on. How to find stars and the celestial sphere. Apart from one nasty question where a labelled star was rather ambiguous, and I picked the one to the left of the label, when it should have been to the right, I did ok on most of these.
  • Astronomical Detectors (5) - focal lengths, resolution of telescopes, all covered under this topic.
  • Spectrographs (3) - use of the grating equation, and other details to do with interpreting spectra of stars comes under this category.
  • Photometry (5) - Things to do with light, star magnitudes and relative brightness under this.
  • Interpreting images (5) - Here you are given pictures of craters and similar on other planets/moons/asteroids. You have to interpret the features, based on light angles and also measure the features given the scale of the image.
  • Experimental uncertainties (6) - How to deal with errors, ending with an absolute stinker of a question where you need to combine experimental errors in an equation involving powers and multiplication to work out what sort of error in one parameter requires in the measurement of another. I did quite a bit of algebra on this, and amazed myself after getting thoroughly confused doing it twice, adapting an equation rather freely, but coming out with a number that was marked correct.
  • Meade Simulator (1) - In this question you are provided with a computer simulation of the Meade Telescope control software, and have to calibrate it and then slew it to a couple of stars and end up with a result that the software then checks. I got it wrong the first time, because I forgot to turn off all the handy feature which projects a map onto the sky! Not very realistic!
Anyway - for most of them you get 3 attempts - and a hint if you get it wrong twice. Your score is reduced if you don't get it right first time.  My results were:
  • 1 where I took the full 3 attempts (that dratted labelled star in the first set)
  • 5 where I had a second go - so correct at the second attempt. Some through stupidity, and some were a fair cop.
  • The rest I managed on the first attempt - after much checking in some cases.
Anyway, so now I'm ready to go - in just over a weeks time!