You are waiting for a plane connection in Denver and happen to strike up a conversation with a modestly dressed person carrying a book bag and a small suitcase, "Where are you headed?" you ask politely. "Oh, to Tucson", he replies. "Visiting family there?" "No, actually I'm going observing at Kitt Peak ". "Oh, that's really interesting. What are you going to observe?", you ask the stranger expecting to hear perhaps about observing cars or something having to do with birds or animals. Instead, the stranger's answer takes you by surprise, "Seyfert galaxies. I'm going to observe Seyfert galaxies. You see, I'm an astronomer from XYZ University."
There are several thousand of us who want to 'go observing'. But you don't just drive up a mountain, knock on the observatory door and say, "Give me the telescope tonight". There's an organized, formal way of assigning telescope time. A would-be observer starts the ball rolling by determining exactly what kinds of observations are needed for studying a particular celestial object, which facilities can support these observations, what time of the year the objects of study will be visible. The observer then writes a formal proposal to specific observatories explaining why these observations are scientifically important and how they will be performed. Sometimes it seems like you practically have to guarantee the committee in charge of scheduling telescope time that you will indeed discover what you had the foresight to look for before you even knew it was there!
The observing proposal is reviewed by the telescope's proposal committee. If they like your idea and think that you have a chance of getting the data you need from their instrument, they'll grant you a block of observing time; if they don't like your idea, you'll get a letter in the mail giving the committee's reasons for rejecting the proposal, and a politely worded invitation to resubmit. A successful proposal is like a blood transfusion to a hemopheliac. Without periodic transfusions of fresh new data, an astronomer's research program may quickly wither away and die. Astronomers with a theoretical leaning are shielded from this process since they use already published observations as the fuel for their research.
Three weeks ago, your observing proposal was accepted. With a spring to your step, you walk to the lab pummeled by billions of photons of light coming from distant objects in the sky. Although the majority come from the bright sky above, you imagine that a small number might be travelers from one of the objects you will soon be studying. They strike your body everywhere and are absorbed by your clothing and your skin, but you don't flinch a muscle in this electromagnetic rain. Once inside, you make your way to your office, pick up your notebooks, calculator, reference articles and airline ticket. In a few hours you're headed to the VLA, Kitt Peak, or perhaps Mauna Kea to start your observing run. In each case, the idea is the same. An object in the sky you are studying emits a stream of radiation in your direction; armed with 20th century technology and a three pound brain, you will try to understand what the object is and what it is doing. Between the light years-distant source and your brain, you place a device that gathers the incipient photons together, selects the ones you want to study, and forms an image of them on a TV screen or a sheet of paper, an image your mind can more easily interpret.
Observing trips take on a variety of forms depending on what your particular program of study entails. If your research requires the optical spectrum of a distant, faint quasar, you will probably wind up at Mt. Palomar, California or Kitt Peak, Arizona to use one of the large optical telescopes there. If you are studying the distribution of plasma in the lobes of an extragalactic radio source, you will probably want to use the radio telescopes at the Very Large Array just outside of Soccoro, New Mexico. And then there are other less well trodden ways to acquire data.
The infrared window of the electromagnetic spectrum is one of the last to be explored by astronomers. Ever since the door to this region was pried open 20 years ago, a dramatically new world of infrared stars and super- luminous galaxies and quasars has been discovered by looking through it. We can now pinpoint and study nearly all of the regions in our galaxy where new generations of stars are being born. Many distant galaxies and quasars are also very bright at wavelengths between 30 and 150 micrometers, revealing that thousands of luminous stars have been born in their interiors. In order to see the universe as clearly as possible through this window, astronomers have to place their instruments as high above the obscuring clutter of the earth's atmosphere as possible. Prior to the launch of the Infrared Astronomical Satellite in 1983, there were only two ways to do this: either using high-altitude balloons, or by using specially equipped jet planes like the Lear Jet or the C-141.