OCA's Astroimagers Tour Palomar Observatory

I was excited! Several weeks ago Dave Kodama announced that he and James Thorp had arranged a special tour of the telescopes on Palomar Mountain. Scott Kardel, Public Relations Coordinator for Palomar Observatory, had given a presentation at the August OCA club meeting about the current research at Palomar. Dave and James spoke with him afterwards and were able to arrange a special tour for the Astroimage SIG with an emphasis toward the imaging done there. The 200" Hale telescope had fascinated me ever since I had read "The Perfect Machine", a wonderful book about the making of this great instrument. Now, we were fortunate enough to get a special tour of it.

At 10 AM on Saturday, September 6th, Scott met about thirty of us in the parking lot on Palomar Mountain in San Diego County.

We caravanned in several cars up to the parking lot at the back of the 200" Hale telescope observatory. There, he pointed out a large concrete disk lying in the dirt at the edge of the parking lot.

Scott Kardel from the Palomar Observatory begins our tour outside the dome of the Hale 200" telescope.

The disk was originally installed in the telescope before the mirror had been finished and was used to simulate the weight of the mirror for the initial balancing of the telescope. After the mirror was delivered, the concrete disk was discarded outside where it sets to this day.

We entered the huge observatory through a small service door and found ourselves in a large storeroom. It reminded me of someone's gigantic basement with lots of very cool stuff lying around. Scott pointed out two large gears hung on the wall that were spare RA and Dec gears that were made were made at the same time as the installed ones.

There was also a large vacuum chamber that was used to aluminize all the mirrors on the mountain except the 200" mirror. A huge structure of steel beams stretched from floor to ceiling some twenty feet up. These provided the support for the massive weight of the 200" telescope on the floor above. They connected to a concrete base that went down twenty feet to bedrock.

Scott led us through a hallway with a series of rooms on either side. Large framed prints of Russell Porter's wonderful drawings of the inner workings of the telescope lined both sides of the hallway. A old fashioned poolroom was behind one door for those cloudy nights.

Behind another, Scott told us were stored many of the original glass photographic plates. Unfortunately, we didn't get in there but he did lead us into a small storeroom that contained a treasure from the past. He had recently discovered the original wooden fixture that had been mounted at the focal plane of 200" telescope. This was used to hold the glass plates that were used by Edwin Hubble and others to take their images. It had long since been replaced by CCD cameras and set aside in this small storeroom. Eventually, Scott hopes to put it on public display.

In another room just down the hall was the adaptive optics unit. This large unit was used on many of the imaging projects to improve the image. It was quite a contrast to the old glass image holder we had just viewed in the previous room and illustrated how well the telescope has been updated with the latest equipment to keep it viable as a scientific instrument.

We climbed a staircase that followed the arc of the of the observatory wall to the main floor. The first thing we saw was the original control panel that was used when the telescope operator was on the main floor responding to commands called down from the astronomer high above in the observer's seat. Amazingly, all the controls still worked except for the clocks.

Just beyond the control panel was the 200" telescope itself. I have always been impressed with the design of the 200" telescope. To walk out across the large open floor with this giant telescope towering above me was quite a thrill.

Cassegrain instrument cage.		Elaborate counterweighting system behind the mirror.		Entryway into one of the mount's arms.

Scott told us all kinds of interesting details and stories about it over the course of at least forty-five minutes. Many of us took the opportunity to photograph it from all kinds of angles. Interestingly, there was also a technician there preparing a camera cooled with liquid nitrogen to be mounted on the scope. Scott led us up a flight of stairs to a second level that was on the same plane as the huge domed roof. From here, we were able to get a very dynamic view of the instrument. He told us to wait a minute while he went back to the first floor control panel where he turned on the motors that rotated the massive dome and the area we were standing on. When we looked up at the telescope, we got a great optical illusion that the scope was turning instead of us! Then, he opened a small doorway that led out onto the steel catwalk that went all the way around the outside of the observatory high above the ground. We got a terrific panoramic view of the mountaintop and all the observatories as the dome rotated around. And we tried to figure out where Anza was with several different opinions.

As we wove our way past shelves of old style oilcans and tools on our way out of the 200" observatory, it reminded me of how successfully this wonderful instrument that was designed and built in the first half of the twentieth century has bridged the decades into the twenty first century.

Everyone piled back into their cars and followed Scott's car out a meandering road to the newest observatory housing the 60" telescope. The observatory is perched on a point overlooking a spectacular view of two valleys. Scott is fortunate enough to have his office in this observatory with a great view out across this expanse. The instrument housed here was originally built with funds provided by the Oscar Mayer Foundation. It didn't take long for it to be known as the "wiener scope". The telescope is quite dramatic when you first see it because the entire tube is wrapped in a highly reflective foil material to keep its temperature stabilized. Interestingly, I was surprised to see it had huge eyepiece mounted on it. The telescope is being modified to be fully robotic. During that downtime, Scott has been using it for organized viewing sessions. Matt Ota had been fortunate enough to go to one several weeks earlier and said the views were very impressive.

Next stop was the 18" Schmidt camera observatory. This is the oldest instrument on the mountain. It went into operation in 1936 and was used continually until its recent retirement from active use.

Many famous astronomers used this venerable old instrument to discover comets and asteroids and map the sky. Gene Shoemaker and David Levy used it to discover the comets that eventually struck Jupiter. A bronze plaque mounted on it commemorates the discoverers for their achievements.

A final drive over to the other side of the mountaintop brought us to the observatory housing the famous 48" Schmidt camera. This telescope has been completely converted from film to CCD instruments. And it is fully remotely controlled from a university back East. Scott warned us to be careful, as it could start moving to a position without warning. I was really struck with how big it is. I have seen many photos of it but they didn't convey the size of it. When I mentioned this to Dave Kodama later he thought the wide- angle lenses used to capture the whole instrument tended to make it look shorter. Makes sense to me.

It too was dramatically coated in the reflective foil to keep it cooler. And with the nitrogen vapor ominously venting out from its cameras inside, it gave the most dynamic sense of being active and ready to image.

After everyone had made their way back outside, we lined up in front of the observatory for a group shot. At this point Scott wrapped up the tour. I think all of us were surprised to hear that this was the first time Scott had put on this kind of specialized tour. Several of the club members who had been on previous Palomar tours said this one was the most extensive and best one they had experienced.

Scott Kardel and the OCA Astroimagers pose for a group shot in front of the historic 48" Schmidt (Oschin) telescope dome. This instrument was used to produce the famous Palomar Sky Survey of the 1950's and 60's.

Back at the parking lot, many of us lingered around to get in a few more photographs, shop at the gift shop, visit the museum and personally thank Scott for the extraordinary tour that had lasted more than three hours!

We're very fortunate to belong to great club in an area with these kinds of treasures nearby. Many thanks to CalTech and Scott for the extraordinary opportunity and to Dave and James for arranging it. What a treat!