Grasslands Observatory - Essays - A Photographic Messier Marathon

A Photographic Messier Marathon:

March 19-20, 1988

By Tim Hunter and Dan Knauss

Messier Marathons have become popular in the last 10-15 years. Near the time of the spring equinox it is possible for an experienced observer to view all the Messier objects in one night. We wondered for some time how many Messier objects could be photographed in one evening with one telescope. Accordingly, we set out to do a photographic Messier Marathon. Our rules were simple. To count as a genuine photograph of a Messier object, images on standard 3.5 x 5-inch prints or on contact prints of the negative sheet had to be easily recognizable as being the Messier object claimed when compared to the photographs in the Messier Album by Mallas and Kreimer.

In early March 1988, two weeks before attempting the photographic marathon, we initiated a thorough review of the objects and their locations, studying star charts, pictures, and written descriptions of them. A field notebook was prepared containing a list of all the Messier objects, their size, type, and estimated magnitude, as well as their coordinates (2000). The list was arranged in object viewing order using a sequence originally suggested by Wally Brown of Phoenix. A list of 20 bright stars (Sirius, Riegel, et cetera) and their coordinates was also drawn up to be used for periodic calibration of our telescope's setting circles throughout the night. This effort took place in 1988 prior to computerized star atlases and digital setting circles.

EQUIPMENT & TECHNIQUES

The 24-inch f/5 Newtonian reflector at the Grasslands Observatory in Southeastern Arizona was used for the marathon. The observatory is located at a superb 5000 foot altitude dark-sky site. The pictures were taken through an Olympus OM1 camera at the telescope’s Newtonian focus. Because the telescope is well aligned and has an excellent drive, no guiding was done. The camera’s horizontal axis was generally aligned in the east-west direction, and the camera was critically focused with a magnifier each time we changed a roll of film. For all the exposures, we used hypersensitized Konica SR-V 3200 film. The objects were initially found either by visual sighting through the telescope’s five-inch f/5 refractor finder, or by using the telescope’s large setting circles. The setting circles were especially needed for speed and accuracy when acquiring objects in the Virgo and Coma Berenices regions. Mallas and Kreimer’s book proved invaluable and was frequently consulted during the night’s efforts. The exposure times ran from one minute for bright open clusters to two minutes for globular clusters and 3 minutes for galaxies, nebulae, and planetaries.