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DFM Engineering

 
 
 
1.3m DFM Telescope Installed
at the
Indian Institute of Astrophysics
 
 

DFM Engineering recently installed a 1.3m F/8 Double Horseshoe telescope at the Vainu Bappu Observatory (VBO) at the historical Indian Institute of Astrophysics (IIA) at Tamil Nadu near Bangalore, India. The DFM installation team consisted of Mark Kelley, Ian Huss and Greg Stevens. Photography credit held by: Dr. Pati Ashok, Chair, 1.3m Steering Committee, Indian Institute of Astrophysics.

Vainu Bappu ObservatoryFor a brief description of the installation challenges created by the location of the VBO, the climate of the region, and the observatory structure, click here. Also, see the image of the Comet ISON obtained by the new 1.3m F/8 DFM telescope.

The installation called for the large telescope parts to be maneuvered through a smaller than usual slit in the dome of a 60 ft. tall, 40 ft. diameter observatory. The other critical elements; the primary mirror, mirror cell and Instrument Interface Unit (IIU) were lifted through a hatch in the observatory floor.

The installation started with an inspection of the observatory and a polar alignment check of the pier. The crane arrived and unpacking of the two containers began. The sole plates were then attached to the concrete pier. The pier has a built-in hatch with a diameter large enough to allow lifting the primary mirror cell from the ground floor to the observatory floor level. Cables were pulled and the hydraulic pump for the telescope bearings was installed. The base frame was unpacked, lifted into place, and attached to the sole plates.

The primary mirror crate was moved into the observatory and the control room was set up.

The horseshoes and the D beams were lifted into the observatory and bolted together using temporary assembly sawhorses (shown in black). The H beam was then installed on the north end of the frame.

The double horseshoe mount tool was lifted from the sawhorses and set onto the radial oil pad bearing on the H beam and frame base. The oil pad bearings had been prepared and were in position. These hydraulic bearing assemblies are located on all four corners of the mount.

The center section was lifted into the observatory. The narrow slit in the dome allowed for only minimal clearance and required careful maneuvering. Once inside the dome, the center section was placed on the primary mirror cell handling hydraulic lift table.

The center section was turned and lifted into position for attachment to the declination axles. Then the motorized counterweights were installed along with the trusses, truss ring and mirror doors.

A dry-run test lift was done with the mirror cell. It was lifted through the hatch. The housing was lifted above the frame. The lift table was moved along the tracks on the frame under the mirror cell. The mirror cell lift table was used to install and remove the mirror cell from the center section.
The dry-run test lift was a success! Then the empty mirror cell was returned to the ground floor to install the mirror.

Next, the primary mirror was unpacked and the blue safety mask removed. The mirror was mounted in the cell, then lifted through the hatch and attached to the center section of the telescope.

The secondary mirror was installed on the focus housing, attached to the spyder ring and prepared for lifting. The focus housing was lifted and attached to the truss ring on the telescope.

The Instrument Interface Unit (IIU) was lifted through the hatch and raised for attachment to the primary mirror cell. The controller was mounted on the center section. A CCD camera and an eyepiece adapter were installed on the IIU for testing.

Dr. Ashok Pati and his staff were on hand during the telescope installation. There were many opportunities for teaching operations and maintenance of the telescope as the telescope was assembled. Dr. Pati was very pleased with the custom 1.3m DFM telescope, the IIU and the professionalism of the DFM engineers and technicians.

The innovative design and impeccable quality of the 1.3m F/8 Double Horseshoe DFM telescope enhances the reputation of the Indian Institute of Astrophysics as a world leader in scientific research.


Vainu Bappu Observatory

History: The IIA is a premier government financed research institution and sponsors a wide variety of programs. The observatory is named for Dr. Vainu Bappu, IIA founder, who dedicated his life toward establishing the world-class research center. The IIA is rich in history and abounding in achievements. The IIA includes multiple observatories, an instrumentation and optics workshop, a variety of telescopes, spectrographs and sophisticated electronics.

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Observatory Structure: The 1.3m telescope and its observatory building is one of several observatories on the IIA campus. The observatory is 60 ft. tall and has a smaller than usual dome slit. The unusual height is needed due to the surrounding vegetation. A very large crane was needed to lift the large telescope parts and maneuver them through the dome slit. Fortunately, the primary mirror and cell are raised and lowered through the hatch in the pier using the dome crane. The mirror handling equipment and procedures were designed by DFM Engineering so no outside crane is needed for routine servicing of the optics or insruments.

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Location: The Vainu Bappu Observatory (VBO) is located in the picturesque neighborhood of the village of Kavalur in the Javadi Hills, in the state of Tamil Nadu south of Bangalore. This area is informally called "Telescope City". The nearest railway station is in Vaniambadi approximately 18 miles away. Arial map: http://www.virtualglobetrotting.com/map/vainu-bappu-observatory

Delivery to the VBO observatory location required extensive planning and special packing and shipping to reach the site.

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Vainu Bappu Observatory

Climate: India is divided into seven different climatic regions. The weather in India varies dramatically based on temperature and rainfall. While the southern tip of India is being lashed by tropical monsoon rain, the north will be blanketed in thick snow. The IIA is located in the Deccan Plateau Region, in south-central India. The Deccan Plateau Region has a tropical climate, so the delivery had to be scheduled to avoid the monsoon season. Because of the weather, the installation was scheduled for early in the year.

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Comet ISON: The comet ISON was first spotted 585 million miles away in September 2012. This is its very first trip around the sun, which means it is still made of pristine matter from the earliest days of the solar system’s formation, its top layers never having been lost by a trip near the sun.

A comet's journey through the solar system is perilous and violent. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether.

Comet ISON recorded at IIA:
8 November, 2013
UT 23:22 (Universal Time)
900 seconds exposure
R filter
1.3m F/8 R-C with field corrector DFM Engineering telescope
Dr. Ashok Pati, Indian Institute of Astrophysics
Vainu Bappu Observatory

Click on the image for the larger version.

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