by John Church

Our historic 6¼-inch Hastings-Byrne refractor, with its objective lens dating from 1879, was ready for the morning of May 9^th and the transit of Mercury. We comfortably followed and photographed the transit with a 55-mm Plossl eyepiece and a solar filter specially made by observatory co-chair Dave Skitt.

Members and guests came throughout the day to enjoy this fairly rare spectacle, averaging only 13 times per century. Most of those transits that could be seen here seem to get clouded out. This time, the clouds stayed away until not long before third and fourth contacts, so we didn’t get to see the end of it, although some members did observe second contact.

The first Mercury transit at which it was used was in 1881 by its original owner, Charles Rockwell, in Honolulu (Sky & Telescope for March 1979, p. 294-300). Several AAAP members made the much shorter trek to this writer’s home in Princeton Junction for the Nov. 10^th, 1973 transit. The scope was being stored there while our observatory was still in the planning stage.

This scope has also been used to time two consecutive transits of Venus, which are far rarer than transits of Mercury. These were in 1882 (again by Rockwell) and 2004, at our Simpson Observatory in Washington Crossing State Park. The 2012 transit was too low in the western sky to be seen at the observatory even if the weather had allowed it, but some members did glimpse it briefly from a garage rooftop in Princeton. The next one won’t be visible here until 2125. We can hardly wait.