On Saturday, 21 November, 1998, Lick Observatory held "appreciation night" for local amateur astronomers who helped with the visitor program last summer. Clouds threatened earlier in the day, and a previous date for this event had been rained out, but at 1300 PST the decision was "go for it", so I went. After errands, I drove up twisty, lovely Mount Hamilton Road, and arrived just before 1600, to find that a mere dozen volunteers had been optimistic enough about the weather to show up.
Nevertheless, the decision was to make the best of things: With cloud and storm ever more likely in winter, and with the 36-inch refractor also used for other things, the probability of scheduling a good night before spring was small. And Lick does have plenty to see. Dr. Elinor Gates, a professional astronomer on the Lick staff, was our escort for the afternoon and evening, and though the dome of the Shane 120-inch telescope seemed big enough for meteorological activity, conditions inside did not impede the tour she conducted.
With her opening remarks, Gates reminded us that the gap between professional and amateur astronomers is not wide. Her words were very familiar to long-term members of the star-party circuit: "You should have come last night!" she said with gleeful enthusiasm. "I had diffraction-limited seeing, and a view of Saturn like I have never had before." She had in fact seen the gap formerly known as Encke's, in the A ring, which is not unreasonable, since the 36-inch refractor with which she had been observing was one of the instruments that participated in its discovery.
I had been in the Shane visitor area before -- it is open to the public during reasonable hours, and affords a nice view of the telescope and of the accessories, parts, and paraphernalia parked around it -- but even so, it was a thrill to walk through doors marked "No Admittance" and "Staff Only", into the open space of the dome. The interior is laid out like a colosseum -- a broad raised gallery circles part of the perimeter, and a narrower, higher one, at the base of the rotating part of the dome, goes all the way around. The truss tube of the telescope stands vertically in the middle, stowed centered between mammoth fork arms, and parked around it are various interchangeable upper ends and several major instruments.
The Shane was oddly familiar: The unsymmetrical Seurrier-trusses that are much favored in large telescope design have made their way in miniature into many Dobson-mounted Newtonians. Half close your eyes, and one might forget that the truss tubes of this unit have diameters greater than the apertures of most of our telescopes. Feeling like mice scurrying at the bases of Obsessions, we wandered around the raised gallery and looked at familiar components of unfamiliar size.
One of the first things I noticed was more people in the visitor's area, waving at us. I waved back, then realized that they were late-arriving volunteers and started making disparaging faces at them. Gates said to let them in anyway.
The Shane can be reconfigured to any of four basic optical and mechanical arrangements, by changing the upper tube section and perhaps inserting an extra flat mirror. Two upper tube sections carry equipment for the prime focus of the ten-foot paraboloid. One has an observer's cage, for instruments or cameras that require a human attendant. This unit is no longer much used -- Gates was the most recent human to occupy it, when the telescope was collimated in July, and she said it might never be used again. Just as well, she indicated, for a session there can be long, cold and hungry -- food and drink are not allowed, for fear of spilling them on the primary -- and you cannot wiggle or rub your hands to warm yourself, for fear of jiggling the instrument. What's more, there are no toilet facilities aloft. Gates commented that after tanking up on coffee and spending a long night in the cage, the many-minutes-to-rise sloth of the access elevator could indeed seem interminable. Why so slow? We weren't sure, but the speculation was that it was an economy measure, using slot-car motors.
A second upper end, configured for remotely operated prime-focus instrumentation, is more often used. The third upper end carries a Cassegrain secondary. Several instruments, large and small, can be attached behind the primary mirror cell, at the conventional Cassegrain focus.
The final upper end carries another hyperboloidal secondary, but with a longer focal ratio and a much larger distance to the secondary focal point. The beam from this one is used with an auxiliary flat mirror, that rotates in declination half as fast as the telescope itself, and reflects the beam down the hollow polar axis to the Coude room, underground and south of the dome, where a massive and precise spectrograph receives the light. This latter instrument is perhaps the most precise of its kind on Earth; Gates said that it had been used to discover more extrasolar planets than at all other sites combined. It can measure radial velocities that differ by as little as a few meters per second -- the difference between walking and running.
The Shane also carries another interesting auxiliary instrument, a 200-Watt sodium laser -- yes, I said 200 Watts, not 200 milliWatts -- whose beam is directed upward to reflect off sodium of meteoric origin high in the atmosphere, as a reference source for an adaptive optics package that removes the effect of seeing and allows the telescope to operate diffraction-limited in the near infrared. Lick's northerly latitude and dry air lets it compete in the infrared with the much higher telescopes on the big island of Hawaii. I asked if there were any plans to extend the adaptive optics into the visual, but there were not -- the feeling was that the sky glow and light pollution of Mount Hamilton would limit that use too much.
In any case, the laser is a threat to eyes in aircraft passing by. The Federal Aviation Administration sets limits on the hours of use of the laser, and requires plane-spotters to warn of intruders near the beam, and there is a radar system that shuts it down automatically, if necessary. That system only works for metallic objects, but apparently the numerous bats that soar over the mountain at night have not been bothered by the laser; at least, none have been reported going down in flames. Bats in the dome continue to provide surprise nocturnal entertainment, and their droppings are among the principal components of debris on the primary during its periodic cleanings.
Raccoons also are occasional nocturnal visitors. Sharing the common lore of procyonids everywhere, that human activity means food, they enter staff areas, undertake search-and-devour missions to all garbage and waste cans, then sneakily hide out in remote corners of the dome, where they must carefully be located and from which they must cautiously be evicted. I told you the gap between professional and amateur astronomers was not as large as it seemed.
All the instruments and instrumentation were wonderful and fascinating. The astronomical optics used to obtain the data for my own doctoral thesis comprised a simple collimator, with approximately as much sophistication as a toilet paper tube with colored cellophane taped across the ends. I'm not going to give my degree back, but it is nice to see fancier devices now and then.
Most of this equipment was much more modern than the telescope. When it was built at mid-century, the Shane was the second largest optical telescope in the world. Now, it is twentieth. Gates commented that the slit in the dome was wide enough to accommodate the beam from a 6.6 meter telescope, and there was some prospect of funding to replace the Shane. Several of us remarked that if that came to pass, then probably the Shane itself would never be used again, which would be a sad fate for an instrument that ranks with the Starship Enterprise at seeking out new worlds. Then again, it would make an interesting ad on AstroMart. While discussing prospects of financing a new instrument, Gates mentioned that she was extremely distantly related to Bill Gates of Microsoft, but the consensus was that the number of people who would have to disappear for her to get a crack at the money was too great for practicality. On the other hand, we all agreed that Bill Gates would make a fine latter-day James Lick, the more so because so many people would like to see him entombed under something large and massive, like the pier of a big telescope.
We descended from the raised gallery and wandered Lilliputian-like around the base of the instrument. Here was the original control panel, looking very 1950s. I was particularly intrigued to see whether a modification that one of my one-time fellow graduate students had allegedly performed, was still in effect. About twenty years ago, I had given him a sticker from the box that one of my eyepieces came in, that said "Passed Japan Telescope Maker's Institute Inspector #____", and he claimed faithfully that he had epoxied it on, next to one of the switches, during one of his runs on the Shane. Alas, it was nowhere to be seen, and I had not thought to bring a replacement. Maybe next time. The controls and readouts were sensible and straightforward, but some of the switches were a bit obscure. No one could figure out what the one labeled "phantom" meant, but there was a notice not to turn it off, and as far as we could tell, no one ever had.
A more modern control room lay nearby -- no sticker there, either -- but here at least there were computers of the digital variety. We regrouped and descended further into the depths of the building.
The primary mirror was ground, polished, and figured beneath the operating floor, using a long testing tunnel that extends for several tens of meters underground. The giant polishing machine still bore streaks of rouge from the final operations, and there was still a small lap -- probably not much over sixteen inches in diameter -- sitting around from local retouching. The mirror blank had been left over from the 200-inch project, unused -- I think I recall that there had at one time been a plan to make it into a flat for autocollimation. In any case, the front surface of the honeycomb blank was not very thick, hence not much glass could be removed in roughing out, hence the rather long focal ratio of the Shane -- over f/5. The mirror is reportedly very good; it was not unrealistic to ask about extending the adaptive optics experiment to obtain diffraction-limited performance in the visual.
Here there was also an aluminizing chamber for the optics. It takes only a few grams of aluminum to coat the surface, and the process is repeated every three years. The mammoth vertical chamber was painted bright red. This fan of colorful telescope apparatus was delighted.
We did not get to see the spectrograph. The coude room is kept much cleaner than the rest of the dome area, not quite to clean-room standards, but it does require bunny suits and use of a fancy shoe-cleaning machine.
The catacombs beneath the dome were also oddly familiar. I have worked in a lab or two with equipment that large, and at one scientific site where it was a whole lot larger. The trappings of scientific technology become civil engineering were much the same in all these locations -- dusty gray paint, streaks of rust, massive girders running this way and that, and Brobdingnagian plumbing and cable troughs. We just hoped the rats and spiders were not equally Brobdingnagian. How long since anyone had been down that testing tunnel, anyway? How long since anyone had come back?
We emerged from the bowels of the dome into murky fog. Promises of coffee, tea, and cake back at the main building did little to assuage our disappointment, but frustration with cake is a clear win over frustration on an empty stomach, so we went. We were all touched and pleased to find the cake not store-bought or catered, but baked by our escort herself. I spent a few moments debating the political correctness of telling a young woman who was a sharp up-and-coming professional astrophysicist that she was a good cook, then rashly went ahead and did it: The only previous experience I had had with confections created by persons with any claim to astrophysical expertise featured me as the chef, and I never dared eat what I had prepared, so I thought the achievement particularly deserving of praise.
The fog was thin and erratic. Occasional looks out the door revealed visibility straight up, so we hung around and chatted, hoping for better conditions. I had Refractor Red, my dayglow Vixen 55 mm fluorite, in the car, so I brought it in and demonstrated why I had been pleased with the color of the giant vacuum chamber. We swapped stories and anecdotes. Presently we found we could see the lights of San Jose, so we went into the dome of the 36-inch refractor.
Lick has strict rules about the meteorological conditions permitted for observing -- wind velocity versus slit orientation, and so on -- and one is an upper limit on relative humidity. The hygrometer attached to the tailstock of the 36-inch stood at 98 percent, which was too much, so we sat around some more, talking about the history and current role of the Great Refractor. The instrument is still used for serious astronomical research -- visual measurements of the position angles and separations of double stars, which are fundamental astronomical data, a cornerstone of our knowledge of stellar masses and therefore of all of stellar structure. It is also in fine shape, optically. The front surface of the crown element had crazed over the years, so it was repolished and necessarily refigured a few years ago. The new figure is reported noticeably better than that achieved by the Clarks.
The mechanics make one wonder a bit, though. Gates moved the telescope around a bit, demonstrating this and that, and the sounds emitted by the remotely operated clutches would warm the heart of anyone who has ever heard what passes for the transmission of a 1930s Ford pick-up. The long tube is cumbersome and can easily acquire a lot of momentum when swinging around. Our guide let it lift her slightly off the elevating floor as she swung it from place to place. That's fine if things are in balance, but one woeful observer once forgot to tie down the back end of the tube when detaching a massive component, and in trying to halt the resulting nose-dive found out the hard way that the accessory was heavier than he was. No one seemed to know whether he let go by himself, or was shaken loose by the jolt when the objective cell hit the floor. The first person to come to his aid found the victim with a broken pelvis and several other injuries, but only after checking that the objective -- which had come loose -- was intact, which it was.
As we chatted, the humidity climbed. When it reached 102 percent, I remarked that since there were no fish swimming around, obviously the gage was out of calibration, so we could ignore it. Nice try. A look outside revealed wispy fog continuing to drift up and over the peak, and increasingly thick cirrus rolling in from the northwest, so we called it a night.
On the way out, we met with other staff members to discuss future prospects and current needs of the visitor program. Lick has been pleased with the public response, and greatful for our assistance, so perhaps there will be more activities and interactions in the future. One person bewailed the need to interact with a recalcitrant database program for managing mailing lists and tickets. We discussed the prospects of typing up the list in a word processor and entering the whole thing as a file, but of course nobody knew what the format was. I remarked that that was no reason to stop, because once we knew we could fix the whole thing in ten seconds with EMacs macros. (EMacs is a text editor that is very popular among programmers.) This suggestion met with Gates's approval: "EMacs macros!" she said with a broad grin, and we slapped palms. I guess I still have a few professional credentials.
There is proably no higher praise I can give to the intrinsic interest of a great observatory than to state that I had a fascinating time there on a soggy and cloud-ridden evening. Lick's modern equipment and rich history made our visit a rare privilege, and one that I shall remember for a long time. Where else in known space can one find at one and the same time, astrometric work that Tycho Brahe or Ptolemy would have understood, and world-discovering projects whereby science boldly goes where only science fiction has gone before? Lick is surely one of California's most golden of treasures, and one of the great scientific sites in the history of the world.