A Day in the life
Just in case anyone who reads this wants to become an astronomer, or just wonders what it is that we do all day, I’m writing up a pretty typical day of observing. Note that, when not at the observatory, the typical day involves analysing data, writing papers, writing observing and grant proposals, and pretty much sitting in front of your computer working. But, really, except for the analysis part, that’s not what anyone became an astronomer for. Observational astronomers, at least, chose the career because we enjoy observing, so that’s what I’m going to write about.
3PM Wake up. Well, actually, you might wake up any time between 2PM and 5PM, depending on where you are and how long the night is. But 3PM is probably about average.
4PM Meeting. Basically, you hear what happened during the day from the day crews, you hear about any changes to the observing plan from the queue co-ordinator, and you discuss any problems that you had the previous night.
4:15PM Supper. Well, for you it’s breakfast, but the meal is supper. If you remembered to ask for a night lunch, you pick that up too.
5PM Head up to the summit. You want to be there in time to have everything ready to start just after twilight, if the weather is good. You see, it’s still too bright until about half an hour after sunset (for science exposures, anyway), but you can still take flatfields (these are important for analysing your data, because they let you figure out if there are any problems with the CCD). You can also take standard stars (reference pictures of stars with known characteristics, also used for calibration and analysis)
6:30PM End of nautical twilight (there are different definitions of twilight, but astronomers tend to use the nautical one). Now, you can start observing.
Observing Basically, at any given time, you look up what the conditions are. What’s the seeing like (lower is better), what’s the cloud cover (less is better), where’s the moon (and in what phase) (dark is better), and so forth. Then, based on that, you look at the available observation programs that can be done with that quality. Of those, you choose one that has a visible target (it’s hard to look at things that are below the horizon). If there are several that still match, you take whichever one was rated highest by the TAC (Time Allocation Committee). Then you move the telescope to the right place, take your acquisition images (short exposures, intended to make sure you actually have the target in the right place), and then start guiding. Every program specifies a guide star for each observation, and you use a smaller telescope to fix on the guide star to keep from deviating too far away from your target. Once you’re guiding, you start taking the exposure. This might be imaging (possibly with a filter, so you only see part of the spectrum) or spectroscopy (with a grating, so the wavelengths are smeared out, and you can see how much light is at each wavelength), and you may be looking at the optical (~3000-10000 angstroms) or infrared. Each observation specifies the configuration of the instrument, and fortunately the telescope systems are usually able to automatically configure the telescope.
Of course, sometimes things don’t go so well. You might have clouds coming over, or various other things that interrupt you. In that case, you can close the shutter and pause the observation, but if you do that for too long too many cosmic rays will hit your detector and you won’t get good quality. You also can’t go too close to the horizon (too much air in the way, and the telescope won’t point too low), and there’s a limit to how long you can follow a target (there’s only so far you can rotate the dome in either direction). So, in general, there’s a lot of stuff that has to be considered in figuring out what to do. So all night you look at one target after another, taking as many exposures as you can (taking into account the varying weather).
5:15AM Start of twilight. More calibrations now. More standards, flatfields, arcs (reference spectra so that you can calibrate your spectroscopy, and figure out the actual dispersion (which wavelengths are where on the CCD), etc. Once you’re finished those, you probably leave the telescope doing daytime calibrations (bias frames, or some such).
6:30AM Go back down to the dorm. Generally, you’ll arrive around 7AM, have your breakfast (although, for you, it’s supper (you had lunch probably around midnight)), and go to bed some time around 7:30AM. Then repeat.
So there you have it. A day in the life of an astronomer. Assuming, of course, that things work well. If they go wrong, the observing part gets a lot more complicated.
3PM Wake up. Well, actually, you might wake up any time between 2PM and 5PM, depending on where you are and how long the night is. But 3PM is probably about average.
4PM Meeting. Basically, you hear what happened during the day from the day crews, you hear about any changes to the observing plan from the queue co-ordinator, and you discuss any problems that you had the previous night.
4:15PM Supper. Well, for you it’s breakfast, but the meal is supper. If you remembered to ask for a night lunch, you pick that up too.
5PM Head up to the summit. You want to be there in time to have everything ready to start just after twilight, if the weather is good. You see, it’s still too bright until about half an hour after sunset (for science exposures, anyway), but you can still take flatfields (these are important for analysing your data, because they let you figure out if there are any problems with the CCD). You can also take standard stars (reference pictures of stars with known characteristics, also used for calibration and analysis)
6:30PM End of nautical twilight (there are different definitions of twilight, but astronomers tend to use the nautical one). Now, you can start observing.
Observing Basically, at any given time, you look up what the conditions are. What’s the seeing like (lower is better), what’s the cloud cover (less is better), where’s the moon (and in what phase) (dark is better), and so forth. Then, based on that, you look at the available observation programs that can be done with that quality. Of those, you choose one that has a visible target (it’s hard to look at things that are below the horizon). If there are several that still match, you take whichever one was rated highest by the TAC (Time Allocation Committee). Then you move the telescope to the right place, take your acquisition images (short exposures, intended to make sure you actually have the target in the right place), and then start guiding. Every program specifies a guide star for each observation, and you use a smaller telescope to fix on the guide star to keep from deviating too far away from your target. Once you’re guiding, you start taking the exposure. This might be imaging (possibly with a filter, so you only see part of the spectrum) or spectroscopy (with a grating, so the wavelengths are smeared out, and you can see how much light is at each wavelength), and you may be looking at the optical (~3000-10000 angstroms) or infrared. Each observation specifies the configuration of the instrument, and fortunately the telescope systems are usually able to automatically configure the telescope.
Of course, sometimes things don’t go so well. You might have clouds coming over, or various other things that interrupt you. In that case, you can close the shutter and pause the observation, but if you do that for too long too many cosmic rays will hit your detector and you won’t get good quality. You also can’t go too close to the horizon (too much air in the way, and the telescope won’t point too low), and there’s a limit to how long you can follow a target (there’s only so far you can rotate the dome in either direction). So, in general, there’s a lot of stuff that has to be considered in figuring out what to do. So all night you look at one target after another, taking as many exposures as you can (taking into account the varying weather).
5:15AM Start of twilight. More calibrations now. More standards, flatfields, arcs (reference spectra so that you can calibrate your spectroscopy, and figure out the actual dispersion (which wavelengths are where on the CCD), etc. Once you’re finished those, you probably leave the telescope doing daytime calibrations (bias frames, or some such).
6:30AM Go back down to the dorm. Generally, you’ll arrive around 7AM, have your breakfast (although, for you, it’s supper (you had lunch probably around midnight)), and go to bed some time around 7:30AM. Then repeat.
So there you have it. A day in the life of an astronomer. Assuming, of course, that things work well. If they go wrong, the observing part gets a lot more complicated.