Observing at Palomar

Since I was too sick to go on the Palomar field trip with the Ay 20 class, I thought I would write about the time I got to observe at Palomar.  Hopefully this will help make up for my lack of Palomar related activities in the past week.

In the summer of 2011, I was working on an astrophysics project at Caltech dealing mostly with flare stars.  (I wrote more about this in one of my earlier posts.)  Near the end of the project, the astrophysics department sent out a notice that they would be accepting proposals from undergraduates to observe at Palomar, provided the data the the undergrads wanted to obtain would be used for some sort of classification or characterization.  Well I was working on characterizing flare stars, and my co-mentor and I realized we could use some spectra to help confirm the nature of some of our flare star targets.  My co-mentor helped me develop a list of targets and told me how finding charts worked, and then I sent in my proposal.  A couple days later, I got an email from the person in charge of organizing the whole thing saying my proposal had been accepted!  I was really excited, since the only telescope I had ever used had been a 6 inch refracting telescope.  It was a decent enough telescope to track asteroids, but now I was going to go to Palomar and use the double spectrograph on the 200 inch Hale telescope!  I was also excited because I had spent the summer of 2010 extracting spectra from images a grad student had taken at Palomar, so now I was getting a chance to see how those images had been obtained.  I was also rather nervous.  What if I messed up the equipment?  Or what if my co-mentor and I had miscalculated and my targets weren't actually visible?  I only had a couple hours with the telescope and I didn't want to waste them.   I guess this is a common worry among astronomers.

I drove up to Palomar with a few other undergraduates and a couple grad students who were there to make sure we didn't screw anything up too badly.  We dropped our stuff off at the residential building.  The observers at Palomar stay in this house called the Monastery.  It is run by a couple who make the place feel very cozy.  There are refrigerators filled with food and a living room full of games and hard candy.  The bedrooms are small, but large enough to have a bed and a desk.  There is usually a Jack-and-Jill style bathroom between every two bedrooms.  I got a thrill thinking of all the famous astrophysicists who might have slept in the same bed I was sleeping in, eaten at the same table I was eating.  The best part of staying at the Monastery was dinner.  The woman who helped run the house was a magnificent cook.  All the hidden astronomers would come out of their rooms and gather around the table around 6:00 pm.  Then we'd all eat and introduce ourselves. After learning somebody's name, the first question everybody asked was "physics or astronomy?"  I'm not sure why this amused me, but it did.  The conversation would almost always then move on to the newest observing techniques for various wavelengths and stay there for the rest of dinner.

Everyday before dinner, we would have to go up to the telescope to calibrate it.  There were two instruments we would could use:  the double spectrograph and the large format camera.  We would have to calibrate whatever instrument we would be using later that night.  We also had to calibrate for different settings, like if we were changing the binning.  If we had time before dinner, we would also start taking flats, biases, and lamp exposures.  These are images of the blank dome, images of zero second exposure time, and images of arc lamps for later wavelength calibration, respectively.  Astronomers use these images to reduce noise and provide a reference for wavelengths for spectra.  If we didn't have time, taking these images would be the first thing we would do after we got back from dinner.

After dinner, it would be time to get right back to telescope to start observing.  One of the things that made observing a little less scary was the idea of "night lunch."  The woman that helped run the Monastery would pack you whatever you wanted in a brown paper bag, provided you filled out the night lunch form in time.  Then she'd put our names on all the bags and we'd carry our night lunches up with us to the telescope.  Just the name "night lunch" made me feel better.  Another aspect of observing that made me less worried about ruining the telescope was the people working with us at Palomar.  They would stay up with us the whole night, helping test the telescope at the beginning and making sure the computers never went down until the sun came up.  Somebody else was in charge of putting in our coordinates and slewing the telescope to our target.  All these people were really easy-going and helpful.  And they knew how to do their jobs very well.  If the person in charge of slewing wasn't sure if she was on target, she knew exactly which guide stars to use to figure out how the telescope was positioned.  They were also good company throughout the night.  Finally, the interface also made me fairly reassured that I wasn't going to break the telescope.  I was rather surprised when I first saw it, because it reminded me of the interfaces I had used in my sophomore physics laboratory classes.  The interface for the double spectrograph was color-coded for the red side and the blue side and there were big buttons at the bottom saying "Go Expose."  All you had to do was enter in the exposure time and how many images you wanted and after the person slewing the telescope told you everything was in place, you just had to press the "Go Expose" buttons and wait for the images to expose.  The most difficult part was remembering to change the file name before you saved an image.

Most of the night I was just sitting in the data room working on my research progress reports and waiting for my targets to come up.  Then I'd spend a couple hours pressing "Go Expose" and waiting for my images to develop and the telescope to slew.  Then I'd leave the controls to somebody else and go back to my progress reports.  Once those of us not observing got bored of waiting and we had extracted all the entertainment we could out of eating our night lunches, we decided to explore the observatory.  We weren't allowed to open the door to the dome when an exposure was being taken, but we got to slip out in between exposures.  And it was awe-inspiring.  The dome the houses the Hale telescope is huge.  It's hard to imagine unless you've been inside it.  The telescope is also enormous.  We had a lot of fun standing on the edge of the room and rotating with the dome when a different part of the sky needed to be exposed.  Then we decided to climb up to the outdoor catwalk surrounding the dome.

The sky was incredible when we stepped outside.  It was so clear.  We could see traces of the Milky Way and the occasional meteor.  Off to the east, I believe, there was a small glow from a nearby forest fire.  Luckily, the smoke wasn't blowing toward us, or our observations could have been interrupted.  It was quite peaceful, although somewhat surreal, to hear only the sound of crickets and the slewing of the telescope.  After staring off into the horizon for a while, I finally asked if the catwalk rotated along with the dome.  As if on cue, the trees and hills in the distance started moving.  Being on the catwalk while it rotated gave us a nice 360 degree view of the surrounding area and then we headed back inside to warm up.

It was finally 5:30 am when we had taken enough morning flats to satisfy the grad student who was observing with us and he gave us permission to go back to the Monastery and go to bed.  Since the sun was not all of the way up yet, as I walked back down the hill from the observatory I convinced myself that it was actually sunset, not sunrise, and I was about to sleep through the night.  I walked into my room and lowered the astronomer black-out shades.  These are by far the coolest window coverings I have seen.  They were a little worn, but they still worked splendidly and blocked out so much light that I was able to continue to delude myself that it was, in fact, not daytime, but nighttime, and therefore entirely appropriate to sleep.  In the early afternoon, it was not the sun that woke me, but birds chirping.  And so the cycle of calibrations, dinner, observing, and sleep started again.

Every once in a while, we would have some free time and get to explore the observatory.  We got to climb up into the cage where the double spectrograph CCD is held and look around.  We also got to take a ride up to the primary focus.  All the light coming from a target is goes through the primary focus, and back when astronomers used photographic plates, they used to sit up there all night long.  There is a ton of equipment in the center of the primary focus cage and then an itty-bitty uncomfortable-looking wooden chair smashed in on the side, in which people like Hubble would have to stay and manage the plates and the telescope.  It was also so cold up there on winter nights that the astronomers had to wear a special outfit that could pump warm water throughout the cloth and around the person.  We also discovered the billiard room.  On nights when it the conditions were too poor to observe, the astronomers would spend their time in the billiard room until the sky cleared up.  We played a couple games while waiting for some of the flats to be taken.  The room still looks like it's from the 1960s or 1970s (not that I would know, since I was born in the 1990s, but stereotypically speaking) with bright orange and brown wall patterns and floors.

After two nights of observing and 9 out of 10 targets (the last one had been too close to the moon and was imaged later when there was a little extra time), I headed down Mount Palomar back to Caltech with the other undergraduate students.  As the conversation in the car turned back to observation techniques and adaptive optics, I daydreamed about the weight I had felt on my finger as I flipped the switch to open the mirror cover on the largest telescope I had ever, and probably will ever, use.  I may not end up being an astronomer and spend my life observing, but I doubt I will ever forget that feeling.  I am very much grateful to the Caltech astrophysics department, as well as to Palomar, for giving me the chance to experience it in the first place.