Technical Information


Optical Astronomy at Purdue University

Cumberland Observatory

Cumberland Elementary School first used Cumberland Observatory when it was built around the year 1970. The Wabash Valley Astronomical Society (WVAS), which was formed in the early 1970s, has used the observatory as a base of operations ever since. After a few years of initial operation, Purdue University became interested in the use of the observatory.

At first Purdue made use of the observatory through the Earth and Atmospheric Science Department. The Purdue Physics Department started using the facility when the ASTR 263-264 class was created. In 1987 the original fourteen-inch Newtonian reflector was replaced by a sleek new Celestron C-14. In the following years, the Physics Department used the observatory to conduct minor research and for class labs. In 1994 they used the Celestron to observe the jovian impact of comet Shoemaker-Levy 9. A senior research team also used the telescope for the photometric analysis of globular clusters.

The Cumberland Obervatory dome was refurbished in 1994. This lead to replacing the Celestron C-14 with a new telescope. In August of 1995, the Physics Department installed a new sixteen-inch Meade LX-200. By September 1995 a CCD was added. The Ring Nebula was an impressive sight!

During the summer of 2002, the Meade telescope was upgraded with a new Apogee Instruments INC CCD and a True Technology Ltd filter wheel. A flip mirror is used to allow use of both the CCD and the eye piece.

Currently, HEAp, ASTR 263-264 and the WVAS all use Cumberland Observatory and the Meade LX-200 and its CCD and filter wheel. Hopefully in the near future, the Department will decide to commission the construction of a new observatory further from the city limits, since current light pollution on Cumberland Avenue limits observability.

Optics at Cumberland Observatory

Statistics on the 16-Inch Meade LX-200 Telescope

Optical Design			Schmidt-Cassegrain 
Clear Aperture			.406 m
Primary Mirror Diameter		.4159 m
Focal Length			4.064 m
Focal Ratio			f/10
Resolution			.28 seconds of arc
Limiting Mv  			15.5
Limiting Photographic M		18.0
Maximum Practical Visual Power	800X
Near Focus			30 m    
Optical Tube Size		.45 m diameter x .83 m long
RA Motor Drive System		4 speed, microprocessor
				controlled 18 V servo 
				motor.  11" worm gear with
				Smart Drive.
Dec Control System    		4 speed, DC servo controlled
				11" worm gear with dec drift
				software and Smart Drive.
Manual Slow-Motion Controls	Dec and RA         
Hand Controller			Motorola 68HC05 
				microcontroller, 2 line x 16
				alphanumeric character
				display, 19 button keypad,
				red LED backlit
Main Controller			16 MHz 68301 microprocessor
				1 M program memory, 64 K
				ram, 4096 byte non-volatile
				memory (EEROM).
Maximum Slew Speed		4 deg/s 
35mm Film Coverage		.49 deg x .34 deg
Net Telescope Weight		215 lbs

Hardware Used with the Telescope

In addition to the Meade LX-200 16-inch Schmidt Cassegrain telescope, the High Energy Astrophysics Group uses a charged-coupled device (CCD) made by Apogee Instruments INC and a True Technology color wheel. They use a Purdue laptop to collect and analyze the images. The laptop is an easy way to transfer the data between the Cumberland Observatory and the High Energy Astrophysics lab on the Purdue University campus.

Statistics on the Apogee CCD

Model                              AP47P
Make                               Apogee 
                                   Instruments INC
Bits                               16
Size                               1024X1024X13u
Computer Port Setup                Parallel Port
Cooling                            HV (motorized fans)
Minimum Temperature                -35 degrees C below ambient
Shutter Time Range                 0.02 seconds to
                                   10,400 seconds
CAM s/n                            A1831
Bias Level Setting                 1778
Maximized Digitized Well Capacity  89k
Gain                               1.4 e-/ADU

Statistics on the True Technology Color Wheel

Make                               True Technology LTD
Number of Filters                  6
Filter diameter                    1.25 inches
Thickness                          2 inches
Current Wheel Configuration        1 - Clear
                                   2 - Red
                                   3 - Green
                                   4 - Blue 
                                   5 - Clear
                                   6 - Open   

Software Used

To collect our images from the CCD and put them into FITS (Flexible Image Transport System) data, we use the MaxIm DL program installed on the Observatory laptop. Back at the Purdue lab, for image processing we use either MaxIm DL or IRAF (Image Reduction and Analysis Facility) on UNIX machines.

This page last updated on Monday, July 29, 2002.