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First Light for Oscir

by Pamela Mydock
UF astronomer Scott Fisher gave AAC members an intimate view of the University of Florida's new, state-of-the-art infrared (IR) camera at September's club meeting. Fisher also detailed his trip to Mauna Kea Observatory where the IR camera (nicknamed Oscir) successfully saw first light. With twice the sensitivity of its nearest competitor, Oscir will make UF a dominant player in IR astronomy

Oscir (pronounced like Oscar) spent his summer vacation in Hawaii, on the big island, on top of Mauna Kea, a dormant volcano. Some of Oscir's Florida friends bought him a round-trip ticket from Gainesville to Hilo. He even had a window seat on the plane. His friends packed wool socks and long underwear because, even in July and August, it is cold at 14,000 feet.

Oscir actually likes it a bit colder than that, about 5 degrees Kelvin. To give you an idea of just how cold that is, consider that water freezes at 273 degrees Kelvin. The only way to get Oscir that cold is with liquid Helium. It takes about ten gallons of the icy cold liquid and about eighteen hours, but Oscir's friends were glad to do it.

Oscir's friends are University of Florida astronomers and Oscir is a brand new kind of infrared (IR) astronomical camera. Oscir looks a bit like R2-D2, the squeaky urn-shaped droid from the movie Star Wars. In fact, the association with Stars Wars is not too far-fetched. Oscir's "brain" is a computer chip that was originally designed as part of the Strategic Defense Initiative ("Star Wars") program. The chip cost over fifty thousand dollars and, according to UF astronomy doctoral student, Scott Fisher, the chip was only "de-classified" six months ago.

"Basically, Oscir looks like a large double thermos," said Fisher. "The outer canister is filled with liquid Nitrogen and the inner canister is filled with liquid Helium." Inside the two foot high cylinder is an electronics array, ten mirrors and a special potassium bromide glass window. Attached to the cylinder is a box of amplification hardware, and on the side of the box is a huge UF Gator sticker, a familiar Gainesville sight.

At a meeting of the Alachua Astronomy Club on Tuesday night, Fisher explained the reason why the new astro-camera must be so cold to operate correctly. The computer chip that is Oscir's brain is "extremely sensitive to radiation wavelengths at ten microns and everything on the planet emits radiation at that wavelength C everything, including you, the telescope, mirrors, dome, dirt, everything." This is because everything on Earth is approximately 300 degrees Kelvin in temperature and therefore radiates energy at infrared wavelengths. The cold reduces radiation "noise."

The ability to see objects that are about the same temperature of the Earth is becoming more important in astronomy. Fisher and his colleagues will use this new technology to study objects such as planets, asteroids, dust shells around stars, Brown Dwarf stars and other extra-galactic objects that are best observed at infrared wavelengths.

Fisher explained the primary reason for pursuing IR research in astronomy is mainly due to dust. The limiting factor for optical observing is absorption of radiant energy at visual wavelengths by intergalactic dust. "Dust is totally transparent in the infrared," said Fisher. Further comparing visual seeing with infrared seeing, he said that "there are only two magnitudes of absorption at the galactic center versus about forty magnitudes with the visual. What we do with IR is equivalent to trying to see a 15th magnitude (very dim) star during the daytime""

The amateur astronomers at the meeting were treated to some rare glimpses of a remote part of our own planet. Fisher showed slides of his journey with Oscir and the other team members, including Dr. Charlie Telesco of UF's infrared laboratory, UF astronomy post-doctoral students Dr. Dave Osip and Dr. Robert Pina. The purpose of the visit to the desolate highlands of Hawaii was for Oscir's first adventure, his initiation on a telescope. Astronomers call this procedure "first light," because it is the first time that light passes though the instrument and actually gets processed by the high-tech electronics.

Oscir got his baptism with light for nine nights, bolted to the infrared telescope on top of Hawaii's sacred mountain. Mauna Kea has been dormant for about one hundred and fifty years, and the new focus of volcanic activity has moved fifty miles away on Mauna Loa. The site on Mauna Kea is excellent for observing, with or without a telescope, mainly because it is above most of the water vapor in the Earth's atmosphere. "There's no trees, no grass, no bushes, just lava rock for miles and miles," Fisher said. "It is so dry there that the stars do not twinkle, and, believe me, you will never, ever see the Milky Way like this anywhere else on Earth. It's quite impressive."

There were some problems on the initial observing run and Oscir now has patches on his hardware and new programs in his EPROMS. Mauna Kea's altitude can take a severe toll on humans; exhaustion and giddiness are common maladies for newcomers. But by the end of their scheduled time, the team had overcome personal and engineering obstacles.

Back in Gainesville, they have perfected the design and are waiting for another time slot on the infrared telescope to test their modifications. Oscir and his friends will return to Hawaii in December. Fisher predicts that ""we are going to put UF on the map with infrared photography. Oscir is twice as sensitive as the nearest competition."

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