2006 marked the Grand Re-Opening of the Joel N. Bloom Observatory located on the Rooftop of The Franklin Institute (originally installed in 1931).  We at the Rittenhouse Astronomical Society celebrate it's re-opening  as it continues the mission of education and inspiration for the next generation of scientists.

Many of us in the Philadelphia area may share a common memory from our youth with our first experience looking through a telescope.  For me, it was on the Rooftop of the Franklin Institute about 30 years ago.  We were observing sunspots with the Institute's giant reflector.  Well time has passed by and the reflector Telescope has been relocated and is now the central attraction of Space Command. The 10" Zeiss refracting telescope has now been refurbished, or should I say rebuilt!

Zeiss 10" Refractor

It turns out that the mechanical complexity of the scope is probably closer to  that of a car than to an ordinary telescope.  This scope has several elements that are unique only to a few scopes in the world.  A system of concentric tubes attached to long shafts with shifting weights that automatically offset the flex of the tube when the scope is in different orientations.  None of this is visible from outside the scope.  It is built into the main optical tube, and is a purely mechanical system.  There are no controls, motors or adjustments necessary.

Another unique element of the scope is that the weight of the entire scope is directed through different supports and casings onto a single large shaft that is counterbalanced by weights hung hidden under the floor.  The mechanical wizardry of its design is breathtaking!

Chris Ray (Antique Telescope Society) and Dr. Fred Orthlieb (Swarthmore College - Mechanical Engineering) teamed up with Derrick Pitts (Franklin Institute Chief Astronomer) in an amazing overhaul of the telescope.  The entire scope was disassembled and transported to Swarthmore College.  Refurbishment involved extensive testing, and covered stripping paint to repacking bearings, to experimenting with new and improved lubricants.  It was an impressive achievement of mechanical ingenuity, creativity, experimentation along with much elbow grease.   We greatly appreciate the expertise of Mr. Ray and Dr. Orthlieb and thank them for their dedication to this task.

   
The Rebuilding                                                                                                                                         Chris Ray, Dr. Fred Ortleib

The results include a completely refurbished mechanical system, now perfect balance (1 finger will move it), a computer guidance system for go-to capability, a new corrosion-resistant paint job, clean optics, and all-new gearing with high precision drive motors.  Operators never really need to physically touch the mechanics of the telescope, the computer drive system sinks in with all drive mechanisms and the giant Zeiss becomes as simple as point and click.  Well, simple if you know a little of what to look for.

On a recent evening we were easily able to find Uranus by using the computer guidance system.  This task was previously impossible since the finder scope on the Zeiss could not collect enough light to see the contrast of Uranus against the light polluted skies over Philadelphia.  Not only could we find Uranus on an average night of seeing, we could also see the faint glowing of the great Orion Nebula.  Unobservable in the finder scope, and almost impossible to find amid city light, now you can zero in on these faint objects using the computer, and the lens of the Zeiss being 10" with its superb optics can collect enough light to see these objects from center city.  I was amazed.

Come and take in the view!  We can also appreciate an entire makeover of the observatory itself!  From the newly installed roof, updated decking and lighting, internet connectivity and CCD imaging, plus the addition of four 8" Meade SCTelescopes. to compliment the view.  All have computer assisted go-to capability and have GPS guidance to aid in alignment for operation.  One is handicap accessible, so all can enjoy the view and thrill of having photons that have traveled in some instances for thousands of years to stimulate the observers retina.

After returning many times through the years, I can now assure you that your next visit will be to what is basically a brand new observatory. The equipment now surpasses the original specifications and mission of the observatory.  In it's prominent position atop the Franklin Institute, the Zeiss telescope can now continue its duties with accuracy, precision and dignity. It can properly serve as a centerpiece piece of Philadelphia's rich history.

Observatory Liaison:

Dr. Carol Ludolph: Rittenhouse Member at Large

Dave Walker:
Ritttenhouse Member at
Large