Located on top of Mauna Loa in Hawaii the Prominence Monitor began operating February 4, 1980 as an analog instrument recording images on 35mm film. Keeping up with technology, the instrument was modified to record images digitally using a Kodak Megaplus Model 1.6 CCD camera and began taking digital images on February 20, 1994. The camera uses an array of 1534x1030 (9 micrometer square) pixels producing 16 bit digital data which is transferred to 8mm tape and shipped to the High Altitude Observatory (HAO) in Boulder, CO. for analysis.
Several different images are taken with the DPMON, limb and disk images and several calibration images. Disk and limb images are taken in the line of Hydrogen alpha, 656.3nm. The limb images are taken by placing an occulting disk in the telescope to block out the disk of the sun. Disk images are taken by removing the occulting disk and placing a narrow band filter (0.7 Angstrom) in the telescope path. Limb and disk images are taken about every 3 minutes resulting in an effective tool for the analysis of prominence and filament activity.
A hourly disk images of raw data are transmitted each day, beginning at 17:05 UT. The quality of the raw images varies with the weather at the Observatory.
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Last revised: 2 November 1999 - A. Stanger