Observations in each region of the electromagnetic spectrum give astronomers a changing view of the universe. At far-infrared wavelengths, you can 'see' warm dust grains in interstellar space heated by young stars. In the microwave region, you can tune in to the radiation produced by various kinds of molecules such as carbon monoxide, ammonia, or formaldehyde, to name a few, which are found in dense, cold clouds. At still longer wavelengths, in the radio region of the spectrum, one can explore very hot ionized gas and electrons moving near the speed of light, trapped in magnetic fields. Each electromagnetic 'window' has its own dominant physical process giving rise to the radiation, and its own collection of objects in the universe. With the balloon and the C-141 observatories, I was mainly studying where young star- forming regions are located in the Milky Way and what they look like. With the 12-meter at Kitt Peak , I had studied the dense, cold clouds in other galaxies within which new stars may be forming. Now, my attention turned to a particular molecular cloud in our galaxy that is located near a supernova remnant called IC- 443. An infrared survey that I conducted showed that there was a young star being born in this cloud, and I wanted to see if there were other, fainter young stars also embedded here. To do this, I submitted an observing proposal to use the Very Large Array radio telescope in New Mexico to map the cloud's radio emission. If any young stars were present that were bright enough, I might be able to detect the radio radiation coming from them.
I arrived in Albuquerque, New Mexico picked up my car, and was soon driving along the west bank of the Rio Grande in the gathering twilight. The scenery along Highway 85 rushed by as the car gobbled up the 70 miles between Albuquerque and Socorro . Stopping at McDonald's in Socorro, I had a quick bite to eat and then continued west on Highway 60 through the 7000 foot high Planes of Augustine into the dark parking lot of the VLA installation.
It was a chilly winter night; I sprinted the short distance to the main office, a three story brown brick building of recent vintage. The front yard was landscaped with stones instead of grass, punctuated here and there by stout-looking bushes. I called the Telescope Operator from an outside phone, and within a few minutes was inside the warm foyer collecting my key to the Visiting Scientist's Quarters. On the bulletin board were announcements of the various colloquia being given this week, but none appealed to me. Several radio photographs of quasars, galaxies and supernova remnants were also hung there for public consumption - the proud trophies of recent observing programs by various lucky astronomers.
With my key in hand, I returned to the car, got my bags and walked to the room I had been assigned. It was just an ordinary room, the kind you might find in most motels, but I would discover the next morning that it had a view unlike anywhere else. Directly beyond the picture window was the southwest arm of the VLA with 9 giant radio telescopes extending nearly to the horizon in either direction. Tomorrow night I would use this fabulous instrument for a precious 4 hours. I could hardly contain my enthusiasm. After unpacking, I returned to the second floor of the main building to check out the Control Room. Within a few hundred square feet were computer terminals and display screens silently announcing the status of each telescope in the array, and showing the progress being made on the current observing program.
Luis Rodriguez from the University of Mexico was studying compact radio sources associated with molecular outflow sources. We knew each other as graduate students at Harvard and we talked briefly about what we had been doing since the last time we saw each other. I asked the Operator a few questions about the observing set-up and then disappeared into the Terminal Room next door. Using the DEC-10 computer, I spent the next hour putting together my schedule for the next night's run. At midnight, I walked over to the Dining Hall, grabbed a sandwich and watched a nameless nature show about Caribou migratory patterns.
Most of the employees working here arrive on the same bus at 8:30 AM, and often stop by the Dining Hall for breakfast or wake-up coffee. I joined the mob and ran into a few people I hadn't seen in years. One of the astronomers turned out to be a high school aquaintance of mine, John Bally, who had also pursued his interest in astronomy to the professional level. I had often wondered what became of him after he had co-discovered Comet 1968d. He had finished his observing run a few days ago, studying magnetic fields in molecular clouds, and was in the middle of calibrating his data. The remainder of the day was open for me to do as I pleased since I had put together and filed my observing plan with the Facility the night before. I did some sightseeing, walking to the nearest radio telescope, gawking at it like a tourist. There were actually some tourists roaming about the VLA complex that afternoon. I stood back and thought my smug thoughts about how I would soon be using this facility tonight to peer into the depths of our galaxy, while they watched their TV programs and ate dinner.
A half hour before my run began, I returned to the control room and let the Operator know the name of my observing file and on what computer it was stored. There were no significant problems with the array that I wasn't already aware of. Antenna 11 on the southwest arm was out of commission for routine servicing and Number 4 on the same arm was experiencing intermittent pointing problems. I would have to keep an eye out for bad data from Number 4 during my observing run. To asuage my curiosity, I selected two antennae to monitor during the course of the program, to check whether the array was seeing anything. Of course if it wasn't, there was little I could do about it anyway. The observing program I had put together was fully automated and it was best not to tinker with it while it was in progress.
In spite of the VLA's enormity, during the time you are observing with it you are completely unaware of the presence of this leviathan machine. The control room's carpeting, plush chairs and 3 TV monitors quickly lull you into thinking that that's all there is to this multi-million dollar instrument. Each of the 27 antennae are represented by a single green line of engineering data on one of the TV screens. The giant picture window looks out onto the surrounding plain, but at night you see nothing but an inky, impenetrable blackness. The only sound you hear is the ever-present whirring of the fans working to keep the computers at the proper temperature. This is not like in the movies where computers and high-tech devices chirp, buzz and bleep. In the real world, the monotonous droning of fans keep silent electronic circuits from overheating. In the future I bet even these will be replaced by more quiet ways of cooling so that computer rooms in that age will probably resemble silent, contemplative monastaries. It amuses me to think that at the VLA, it is easier for me to tune-in to the radio signals from a quasar a billion light years away, than to receive the local broadcasts from Albuquerque just down the road a few hundred miles.
Observing at the VLA has become such a routine matter that, for certain programs, it is actually quite boring. After a decade of operation and thousands of observing programs, there's an excellent chance that your program will fit into one of the well known observing schemes. My particular project was such a program. All 27 antennae would be commanded to point to a specific part of the sky near the supernova remnant IC 443, an expanding cloud that is all that remains of a star that died 20,000 years ago. The telescope will accumulate radio photons from ths region at two wavelengths, and after 10 minutes move to a neighboring part of the sky to repeat the process. At 30- minute intervals, the VLA will observe a nearby calibration source to obtain a reference signal. Everything is recorded automatically on magnetic tape. If the status of any antenna changes during your run, the Operator makes a note of it in the observing log, which you get a copy of. So, rather than nursemaid the data as it comes in, you tell the Operator to call you on the phone if anything happens, and you go to the Dining Hall to eat dinner and watch TV. In contrast to this evening's idleness will be tomorrow's rush to calibrate the data and eventually assemble it into two maps.
Unlike its sister facility at Greenbank, West Virginia , the VLA does not have many recreational diversions. At Greenbank, the visiting astronomer is assigned a bicycle during summer trips, can enjoy a dip in the pool or a game of tennis. A cheerful lounge with a cozy fireplace and plush chairs can be used to unwind with. There is even a VCR at the astronomer's disposal, though the selection of cassettes is limited to only one entitled "A Quarter Century of Science on the Meridian - The 300 Foot Telescope" ( Aw come-on guy's, give me a break!).
By the way, for those of you not familiar with the verb 'to calibrate,' let me explain. Along with the unknown radio sources that I hoped would be 'in the data', I had also observed two radio sources whose brightness and appearance at 2 and 6 centimeters wavelength were well-known. Using these 'Standard Calibrators' as well as some fancy computer programs, I will be able to put the brightnesses of the unknown sources onto a standardized scale. What sounds like a simple operation is actually rather complicated because some of your data might be bad due to radio interference, faulty pointing or occasionally flaky receivers. This bad data has to be identified and removed before any usable maps of your radio sources can be made. What I do at this step will rapidly snowball in impact once I start to interpret the data and draw conclusions from it. Fortunately, this procedure has been done thousands of times before with the VLA computers, and there are detailed 'cookbooks' available that carefully guide the novice through the calibration maze. If the cookbooks don't work, you can always ask a Data Aid who has probably encountered your particular problem before.
Nine hours and five Cokes later I was finished. Not only was my run rather uneventful, but also the calibration of the data did not present any major problems. I was forced to drop out antennae 14, 18, and 20 since their brightness measurements on the calibrator sources had unacceptably high noise values. But, I still had 23 antennae worth of good data, more than enough to make the maps I needed. My calibrated data was transfered from magnetic disk to tape and I picked the tape up in the computer room next door.
For dinner, I joined astronomers Jean Turner and Phil Myers from Harvard at a locally famous restaurant `The Eagle Guest Ranch' in the nearby town of Datil. This restaurant, one of the few business establishments in town, has on its menu 16 and 32 oz sirloin steaks. These monstrous pieces of broiled flesh are served in skillets for that 'homey' touch, and were more than a match for any appetite that the VLA could induce. Phil and Jean were here collaborating on a study of dense dark clouds in interstellar space, hoping to see the tell-tale signs of stars about to form out of collapsing gas. Of course, the conversation had to include the quirks of the VLA data analysis. I returned to the VLA, said my good-bys and wandered over to the Dining Hall to watch 'Magnum, P.I.' before going to bed.