Photo by John Stone

The Astro-Research 24 inch carbon fiber OTA on a SB Paramount ME

Our quest was to place the largest telescope possible on the current Software Bisque Paramount ME that was located in Astronomical Research Observatory I.  The design, is a 24 inch ( 0.61m ) astrograph that is similar to the 32 inch (0.81m) telescope we designed and built previously.  Mike Lockwood owner of Lockwood Custom Optics also made the 24" mirror for this telescope and the final results speak volumes literally.  In the past year over 200 observations were published in the MPECs with this telescope to unfiltered magnitude 22.2.  As an astrograph, the camera operates at the prime focus, so no secondary mirror is used.  This eliminates an additional optical surface which may introduce errors and eliminates light loss due to absorption by an additional optical component.  The difference on this project compared to the 32 inch telescope is the use of light weight carbon fiber technology to create an optical tube assembly that weighs less than 150 lbs.   With extensive use of carbon fiber and aluminum tubing, this allowed the production of a telescope weighing only 143 pounds (65 kilograms).  This is 7 lbs less than the design weight limitation of the SB Paramount ME.  Truss tubes, mirror cell, and camera mount were all made using carbon fiber to reduce weight.  Our secondary goal was to eliminate nearly all the expansion and contraction problems associated with focusing using metallic truss tubes.  No data has been obtained yet for variations in focus based on the expansion coefficient of the carbon fiber truss tubes.  Analysis of the structural properties of carbon fiber truss tubes were quite surprising with less than 12 arc/sec of  total flexure from horizon to horizon.  The primary mirror is a solid Pyrex blank 24 inches ( 0.61m ) in diameter, 1.6 inches thick, figured to better than 1/16 wave with a weight of just 59 pounds (26.82 kg) to keep the overall optical tube assembly light weight.  

The Astronomical Research Observatory (ARO) was constructed for the purpose of operating follow-up observations to the large sky surveys in Near Earth Object Observations, asteroid, supernova and AGN research that could be used in Astronomical Research Institute education and public outreach programs.  On July 1, 2008 this telescope made the discovery of  C/2008 N1 (Holmes) while conducting routine near earth object observations.  The CCD camera is a Santa Barbara Instruments Group STL 1001E with 24 micron pixels and a 1024x1024 array.  The telescope and CCD camera are controlled using Software Bisque software including The Sky Professional, CCD-Soft, Orchestrate, and T-Point.  


24 inch telescope image of M87

First light image 24 inch telescope M87 - May 8th 2007

 These images were taken during 8-12 mph winds, a testament to the rigidity of the Paramount ME working at full capacity.  Light cirrus clouds no moon.  Exposure time - 180 seconds.  See magnitude measures.


24 inch telescope image of M51

24 inch telescope image of M51 - 180 seconds


24 inch astrograph image of M13

24 inch telescope image -  M 13 - 300 second image. 

Note at the lower left is galaxy IC 4617 at magnitude 16.0 Blue


We work on research images at ARI so none of the images were taken with filters to produce color.  Note that there is slight elongation of the star images due to wind.   Exposure time - 180 Seconds

Image scale for the Astro-Research 24 inch is 1.59 arc/sec per pixel with a field of view that is 27.20 x 27.20 arc minutes.  Focal length is 122.2 inches ( 3105mm ) at f/5.17 using a Televue STL-ParaCorr.   Limiting magnitude with this telescope is expected to be unfiltered magnitude 20.4 with a 60 second exposure.  

The retractable roof design suited our current needs better than a dome for full access to the sky without dome rotation problems.  In addition, it was more economical allowing us to place our funds into telescopes and CCD imaging devices rather than buildings to house our equipment.    The current Paramount -  Astro-Research 24 inch telescope will operate in the observatory conducting NEO observations.


Carbon Fiber 24 inch telescope (0.61m) Components

carbon fiber truss tubes, mirror cell triangle, camera mount baffle tube


24 inch Instrumentation Design

Design Analysis For the Astro-Research (0.61 meter) 24" f/5.32 Telescope

Length of OTA w/camera installed
117.75 inch       (299.1 cm)
Outside Diameter of OTA
31.10 inch         (79 cm)
Primary Mirror Diameter
24 inch               (0.61 meter)
Focal Length with Televue ParaCorr
125.78 inches         (3195mm)
Central Obstruction 6.55" Prime Focus CCD Camera
143 lbs
Carbon Fiber - Aluminum Construction  


                                 Mirror Specifications

Focal Ratio
Waves Of Correction Primary Mirror
Mirror Sagitta
Airy Disk Size (Microns)
Aperture Size In Square Inches
452 sq. inches
Coatings - Spectrum  Coatings
96% reflective

                        Telescope Specifications 

Light Gathering X Human Eye
5 min exp. Approx  CCD Limiting Magnitude 90% Probability
21.24 unfiltered
5 min exp. Approx  CCD Limiting Magnitude 10% Probability
21.54 unfiltered
Theoretical Resolution
Field Of View With a SBIG STL1001E
26.40' x 26.40'
CCD Resolution  of the                   SBIG STL 1001E  (24 micron pixels)
1.55 arc sec/pixel
Tube Design
Open Truss
Optical Baffling
Primary, Camera
Coma Correction
Televue ParaCorr STL Series

                                 Mount Specifications

Mount Type - GEM
Software Bisque Paramount ME


Other first night images and data.

24 inch telescope image of M100

24 inch telescope M 100 Exposure - 180 Seconds

0.61m astrograph

M87 first light image - Limiting magnitude 21.1 in a 180 second exposure.  Reference above is a 20.6 magnitude star based on 290 photometric reference stars and image has been flipped for astrometry and photometry.  Above image has been enlarged 200% to show detail.  Additional data below.

carbon fiber telescope


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