324 Bamberga

324 Bamberga is the 16th biggest asteroid in the Main asteroid belt. It was found by Johann Palisa on February 25, 1892 in Vienna, making it one of the last big (diameter over 200 km) asteroids found. Apart from the near-earth asteroid Eros, it was the last asteroid which is ever easily visible with binoculars to be found.

Although its very high orbital eccentricity means its opposition magnitude varies a lot, at a rare opposition near perihelion Bamberga can reach a magnitude of +8.0, which is as bright as Saturn's moon Titan. Such near-perihelion oppositions happen on a regular cycle every twenty-two years, with the last happening in 1991 and the next in 2013. Its brightness at these rare near-perihelion oppositions makes Bamberga the brightest C-type asteroid, about one magnitude brighter than 10 Hygiea's maximum brightness of around +9.1. At such an opposition Bamberga can in fact be closer to Earth than any main belt asteroid with magnitude above +9.5, getting as close as 0.78 AU. For comparison, 7 Iris never comes closer than 0.85 AU and 4 Vesta never closer than 1.13 AU when it becomes visible to the naked eye in a pollution-free sky.

Overall Bamberga is the tenth brightest main belt asteroid after, in order, Vesta, Pallas, Ceres, Iris, Hebe, Juno, Melpomene, Eunomia and Flora. Its high eccentricity (for comparison 36% higher than that of Pluto), though, means that at most oppositions other asteroids reach higher magnitudes.

It has an unusually long rotation period among the big asteroids. Its spectral class is between the C-type and P-type asteroids.

An occultation of Bamberga was seen on 8 December, 1987, and gave a diameter of about 228 km, in agreement with IRAS results.

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Category:Asteroids