The Remote Observing Facility doesn't look special from the outside. It's one of many featureless white doors on the maze-like first floor of Caltech's Cahill Center for Astronomy and Astrophysics. Tonight, though, it's the only door propped open, and from down the hallway, you can hear the voices of its occupants, busy setting up for the next twelve hours of work. When work begins for the night, it's 8 pm, Pacific Time--that's 6 pm, in Hawai'i, where the Keck Telescope is located.
Inside the windowless room, there are three digital clocks. The first gives the current Greenwich Mean Time, a number that is dutifully recorded at the beginning of each exposure of the telescope. Another gives the time in Hawai'i, keeping track of sunset, sunrise, and twilight on the distant island. Finally, the clock in the middle keeps track of the local time in Pasadena, the only real link to the rhythms of daily life outside of the strange limbo-like atmosphere of the office.
The first step is to turn on and calibrate the instruments and run through a series of checklists for the telescope. Under the row of clocks, a webcam whirs to life, and three panels on the monitor below it blink on. The first is dark--later, when observing starts, it connects us to the telescope operator. She sits at the summit of Mauna Kea, moves the telescope into position, and sets up guidance and tracking so that the telescope stays pointed in a fixed direction as the Earth rotates beneath it. The second shows the telescope technician, located at the base of the mountain and acts as IT for the night. The last one is an image of me and the other occupants of the ROF.
Observing officially begins at the end of astronomical twilight. The targets are potential Kuiper Belt Objects1, identified by another telescope on a previous night and picked out by a computer as likely candidates. The idea behind these detections is what researcher Mike Brown calls "blinky-blinky," observe a patch of sky at two different times, and see if anything has moved. Look a third time, just to make sure the apparent movement wasn't caused by random noise in the instrument. If the object is seen in three different places, along a straight line, there's a good chance what you've found is real.
This is the same method Clyde Tombaugh used to discover Pluto, only he did it by literally blinking between two images. Today, Pluto-killer Mike Brown has autonomous programs to do it for him. For any given candidate object, the computer even spits out potential distances and orbits. Intuitively, this makes sense: objects that are farther away appear to move more slowly across the sky per unit time.
Looking at follow up targets several months later allows for a confirmation of candidates' existence, as well as a narrowing down of orbital properties. Observations fall into a particular routine. Every two minutes, we move onto a new target. We press a button to expose the telescope--it's essentially the same process as taking a long exposure image with a digital camera--and note the time. Two minutes later, we reposition the telescope, get an "okay"from the summit, and expose again. Every so often, the telescope gets re-aligned with a guide star of known position, and observations resume. Research continues like this for the next eight hours. Once we get two exposures of the same object, we can do our own makeshift "blinky-blinky" to get a first look at the data as it arrives.
Luckily for me, finals week means I leave the ROF early after only half a night of observing. Mike Brown2 and the rest of his team stay up until dawn, searching the clear Hawai'ian skies for distant worlds.
1 Kuiper Belt Objects are icy bodies that orbit near Neptune and beyond. When you think about Kuiper Belt Objects, think about Pluto-like objects.
2 Mike Brown also does some neat research on Europa.
