Ellen I have been visiting the Hat Creek Radio Observatory since the mid-1980s, after I read about the observatory in an amateur radio astronomy news letter. In the1980s and early 90s I was very interested in amateur radio astronomy, and I traded some equipment with one of the observatory staff. But, that is another story.
The Observatory was founded in the late 1950s by the Radio Astronomy Laboratory of the University of California, Berkeley. An 85-foot antenna was installed in 1962 and operated until 1993, when it collapsed during a wind storm.
The earliest experiments in millimeter-wave astronomy were performed at this site starting in the 1970s when a 2-element interferometer was constructed. From 1980-1985 a 3-element interferometer was constructed, with another four antennas added between 1990-1992.
It was thrilling to standing among the array when the antennas moved in unison as they shift to a new observation point.
After the 85-foot dish was lost, another three antennas were added to the millimeter array for a total of ten elements. This expansion was in collaboration with the Universities of California, Illinois, and Maryland and the observatory was re-named the BIMA telescope.
The BIMA telescope array was moved to Cedar Flat near the Owens Valley Observatory in the spring of 2005 to be combined with other millimeter antennas as part of the Combined Array for Research in Millimeter-wave Astronomy project and to make way for the Allen Telescope Array (ATA).
We had tried to visit the ATA several times, but the site is not open on the weekends when we were camping at the Hereford Ranch. Visitors are welcome during the week from 9:00 to 4:00 daily, except for holidays. Tuesday of last week Ellen and I finally manages to visit and tour the ATA facility.
Our tour guide was Carol, a recent Berkeley graduate in Planetary Science. She did an excellent job in explaining how the ATA is used for both SETI, the Search for Extraterrestrial Intelligence and standard radio astronomy. The complex antenna feed and processing system can do both interferometer and beam shaping. This allows dual use of this facility.
You can read more about SETI and the ATA here.
Visiting the ATA is a great field trip for a son, daughter, or grandson or granddaughter, who are interested in science, especially astronomy or SETI. It is about a 3:45 drive from Nevada City one way, but there are some great camp ground in the area and motels in Burney. We can highly recommend the Hereford Ranch RV Park just a few miles from Burney, CA and right next door to the ATA.
Following our visit, our grandson and granddaughter visited the ATA several days latter with their parents. The children had a lot of questions for Carol, and came away energized about studying science.