From the President...

ASN’s 24” Scope sees First Light

The ASN’s 24” truss-tube dobsonian has not been used since approximately 2010.  In January through June 2015, the scope was restored and rebuilt by current ASN members. First light was in Palomino Valley on July 11, 2015!

Our 24" scope was built by ASN members in 1991 and rebuilt in 2002 using the mirror and support frame from the original scope. Thus the scope is a legacy from former ASN members and was updated with modern tools.

Here is a list of the upgrades to the scope:

-Optical encoders and a dedicated computer were installed. The scope is a “push to” rather than a “go to” type, in which the computer serves as a guide to find objects in the sky.

-Variable-speed fans were added to cool the primary mirror. There are two fans above the mirror and two below, operated on independent control circuits. Operation of the fans is indicated by LEDs on each circuit.

-The optical design was modified by extending the optical tube length, enabling the use of a smaller secondary mirror. The smaller secondary will improve image contrast. (The scope’s secondary had to be replaced anyway due to damage to the “2002” secondary.)

-The damaged secondary mirror was replaced with a high-quality 1/20 wave mirror.

-The scope’s optical specifications were checked with bench tests and a ray-tracing computer program, which was not available when the scope was originally built.

-A custom-made fabric shroud was added to cover the truss tube assembly, blocking stray light from reaching the eyepiece.

-An 8x40 finder scope was added to complement the existing Telerad finder.

-The scope’s fine balance was maintained and optimized through all these modifications by using the 12-volt wet-cell battery as a counterweight.

-The scope’s wheely bars were sanded and repainted and a handlebar was added.

- About 20% of the parts cost and all of the labor involved in the restoration were donated by ASN members.

-The club established a committee to manage and maintain this scope, and one for our 20” Obsession scope.



Category: President