Joel N. Bloom Observatory

Joel N Bloom Observatory

The Franklin Institute's Joel N. Bloom Observatory treats visitors to day and nighttime viewing with its 10-inch Zeiss refractor and four Celestron CPC 800 GPS Computerized Telescopes, 8" Schmidt-Cassegrain models. The instruments provide visitors and local astronomy clubs with views of most planets and bright stars, several star clusters and nebulae, and a few galaxies. It is one of a handful of observatories in the country to provide optically safe, real-time direct observation of solar activity such as flares and prominences.

The original observatory, opened in 1934, had two telescopes. The 10-inch, f/15 refractor, built by Carl Zeiss Jena, employed the latest optical and engineering techniques available in pre-World War II Germany. The 24-inch reflector telescope, manufactured by J.W. Fecker of Pittsburgh, was a convertible Newtonian/Cassegrain instrument with focal ratios of 14.4 and 7, respectively. The reflector was used for deep-sky observations, including the first recovery sighting of Comet Halley in the fall of 1985. City light pollution eventually rendered it ineffective, and the scope was moved to the Institute's Space Command exhibit.

Bloom Observatory was renovated in 2006. Nationally-recognized telescope mechanic, Christopher Ray, of Ray Museum Studios and a professor of Mechanical Engineering from Swarthmore College, completely rebuilt the Zeiss refractor, upgrading it with modern PC-controlled DC-servo drives to achieve GO-TO pointing accuracy of better than 0.2 arc-seconds on both axes. The upgrade enables visitors to see not only the only the usual, but also thousands of faint objects (down to about magnitude 13)--despite high levels of ambient light pollution.

Today, the observatory is open daily, weather permitting, to observe the Sun, Moon, Jupiter, and depending on sky conditions-Saturn and Venus. At night, the Observatory has eyepieces to provide magnifications from 35 to 468 power, for both normal-view and wide-field for open cluster observation. All of the telescopes are micro-processor controlled motor-driven with GO-TO (automatic targeting and telescope positioning) capability. Two are mounted on electrically driven, height-adjustable piers.

The observatory is operated and maintained by The Franklin's Chief Astronomer Derrick Pitts, and staffed by a cadre of knowledgeable volunteers.

Joel N. Bloom was director and president of The Franklin Institute Science Museum from 1969 until 1990. The observatory is named in his honor.

For more information, send an email message to Derrick Pitts, Chief Astronomer, The Franklin Institute.

Night Skies in the Observatory