Certainly 2009 is beginning to wind down. In a week I will be heading to Idaho for Christmas. But, there’s lots to do before then!
The most pressing is certainly grading the last few labs for the 100-level Intro to Observing class. Final grades are due soon so I have 30 or so labs left to grade. 10 or so are the “Navigation by the Sun” lab, in which students use a sextant to determine the latitude and longitude of the lab area. If done carefully, it is possible to determine the position of the lab area to within a nautical mile. Generally though, the accuracy is such that students can only say they’re somewhere in the state of Virginia. Still though, not many people can say they’ve ever used a sextant!
Right after the New Year is the American Astronomical Society winter meeting in Washington, DC. I will be presenting a poster based on my MS thesis. Of course, the poster still needs to be made!
The last task that needs to be accomplished is the assignment of TA duties for the Spring semester. Fortunately, this doesn’t need to be done until the beginning of January. But given the complexity of dividing up the lab duties in an appropriate manner between ~10 TAs, it takes a bit of time (and iteration!).
So, that’s the list of glamorous things in the life of a grad student at the end of the semester.
As I write this, we are just getting on-sky with the Green Bank Telescope to do some neutral hydrogen (HI) observations. We are remotely observing and David is at the controls getting things going. The first step is to focus the telescope (easy to do at L-band!), determine pointing offsets (difference between where the telescope thinks it’s pointing, and where it actually is pointing), and balance the IF rack (ensure the system responds linearly to incoming signal). This first portion takes about 10 minutes or so. Once that is done, we will move to a strong calibrator source, generally a radio loud quasar or a radio galaxy which is unresolved by the GBT. We will do quick observations of a calibrator so we can later calibrate our data to accurate measurements.
Once the setup and calibration is completed, we will move to our source and begin taking data. This evening’s observations are part of a modest survey to look for HI in compact groups of galaxies. They are an interesting selection of objects, much smaller than large galaxy clusters or groups. There is a mix of elliptical galaxies and spiral galaxies, although elliptical galaxies seem to be more prevalent. We only have a 1.5 hour observing block tonight, so with calibrations and overhead (slewing the telescope, etc), we will only be observing a single compact group. We have already observed a number of groups, and will observe more during future runs, including one tomorrow and one on Wednesday.
But, soon it’s off to the calibrator!
As noted before, the semester is winding down here at UVa. As a result, a good chunk of the weekend has been spent grading the flood of labs that always appears at the end of the semester. Pretty much all day yesterday was absorbed grading the labs for the Intro to Observing class. As I am head TA for that class, I am intimately involved in helping assign final grades for the semester. With a somewhat complicated set of deadlines, it will involve lots of checking to make sure the labs have been properly dated.
On Friday I put in a good chunk of work reducing the GBT data I had acquired in March. I am about 90% done with the first galaxy, just a bit of double-checking to do for quality control. I think we have made the first measurement of the neutral hydrogen gas in this particular galaxy. While that is nothing special in and of itself, I believe we have also detected absorption of the radio source by another component of neutral hydrogen. Unfortunately, due to the fact that we used the GBT and the beam is significantly larger than the galaxy, we can’t localize any of it. However, the existing data will be included in a paper currently being finished up (and hopefully published soon).
Continuing with the working theme, this morning was spent on the take-home portion of the final exam for the Extragalactic Astronomy II class. Fortunately it turned out to be fairly straightforward. Since then I have been writing my thesis defense talk. It is just over a week away and I must admit I found the prospect of writing a 45 minute talk somewhat daunting. However, now that I’ve actually started working on it, I feel better about it. It is probably easier since I can use my thesis for an outline to guide the talk. There are already 18 slides and I am still working on background information. At ~1 min/slide I should manage to get it around 45 minutes without too much trouble.
I’ll spend the rest of the afternoon working on the slides. My last final (ever?) is tomorrow afternoon so this evening and tomorrow morning will be devoted to studying. Then, back to grading and working on the defense.
The next week and a half will be quite busy, but at least there’s a light at the end of the tunnel! On May 14th I will get to see my brother graduate from Notre Dame! Following that, I’ll be joining my family for a vacation. Looking forward to the break!
I had a bit of two worlds this evening… I headed out to Moorman’s boulders after work to do a bit of climbing before the sun went down. I was feeling pretty mellow today, so I didn’t push things too hard. Worked some problems that I’d been trying before, tried some new ones, and sent some “old friends”. I went with another graduate student at UVa (though not in the astro dept!), who showed me a couple other problems there that I hadn’t tried before.. Good times all around, and minimal pain to the fingers.
After bouldering, I finished up some lab grading I’d been working on during the afternoon. Still have another lab to grade as well as a midterm for a 100 level class. Should be a busy weekend.
I’ve just wrapped up my night’s effort to reduce the data taken at the Green Bank Telescope. I am using the GBTIDL software package to reduce the data. So far I’ve only been flagging bad data in the scans of our targets. Due to the low amount of radio frequency interference (RFI) in Green Bank, only ~1 minute of total data was severely affected in the several hours of data taken! Now that I’ve got the hang of flagging obviously bad data, the next step is to calibrate the spectra using the flux calibrators observed during the run. This involves a conversion of antenna temperature (T_A which measures the strength of the signal measured by the receiver) to an actual flux value with the gain and any atmospheric opacity taken into account…
But I think it’s time to call it a night. Have a full day of meetings, classes, and talks planned for tomorrow!
The observing run has been going quite smoothly so far. I haven’t had any trouble with the telescope or any other equipment. RFI seems to have been minimal as well. I’ve split the 10 hours I’ve used so far between two galaxies; 3 hours on one, and 7 on the other. I’m planning to spend the rest of the night on the latter galaxy, giving it about 9 hours total. This, plus some calibrations should wrap up the night nicely.
Quick looks at the data are promising. Our observing program was intended to look at two Seyfert galaxies which have upper limits on the neutral hydrogen (HI) mass. Using the improved sensitivity of the Green Bank Telescope, we were hoping to detect emission from the HI and possibly use the information to fir another piece of the puzzle for the two galaxies. As I said, things are looking promising, I think we might have detected the HI in both galaxies along with some other potentially interesting features. A proper reduction will be necessary to make be certain however.
Observing here in Green Bank has been a great experience. I’ve enjoyed meeting the staff here and enjoyed using the telescope. I hope I can come back, although the option to observe remotely exists.
At any rate, my observations are automated for the next 2 hours, so I think I’m going to catch a quick nap…
