The Official Publication of the Bucks-Mont Astronomical Association, Inc ________________________________________________________________________________________________________________________________________

VOL XV, NO 4                                                               APRIL 2000                                                               Scott Petersen, Editor
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DAVID FAIR, Outreach Coordinator at Goddard Spaceflight Center will speak at 2:00p.

He was a very popular speaker last year with his talk about the daily lives of an astronaut on a space mission.

And this year he should prove to be equally as interesting.

There will be a mirror grinding demonstration, telescope clinic and solar observing during the day,

followed by a public StarWatch at 8:00p.

Lots of club participation is needed, so please contact Linda van der Spek to help.

We will also enter into the Sky & Tel/Astronomical League Astronomy Day Contest with photos and descriptions of our festivities, in hopes of winning the competition.

See you there!

The CONSTELLATION is the official publication of the Bucks-Mont Astronomical Association, Inc, a 501(c)3 non-profit organization incorporated in the Commonwealth of Pennsylvania and exists for the exchange of ideas, news, information and publicity among the BMAA membership, as well as the amateur astronomy community at large. The views expressed are not necessarily those of BMAA, but of the contributors and are edited to fit within the format and confines of the publication. Unsolicited articles relevant to astronomy are welcomed and may be submitted to the Editor.

Submission deadline for articles is the 15th of the month prior to publication.

SCOTT PETERSEN
CONSTELLATION EDITOR
WYCOMBE PA 18980-0333
TEL: 215/598-8447
FAX: 215/598-8446

BMAA WEB SITE: www.freeyellow.com/members2/bmaa/

2000 Calendar Of Events

Stressful situations will sometimes cement friendships, but attaining good telescope optical alignment will more likely destroy a friendship. It is frustratingly difficult for the observer at the focuser to get the guy tweaking the nuts at the other end to do the right thing at the right time. Use of a video camera, coupled with a light emitting diode (LED) to replace the center dot makes the job faster (even with set-up time of the camera), much less frustrating and often improves results. Moreover, the technique allows one person to do the job - particularly if you have lost all your friends to attaining optical alignment in the past!

The technique requires a video camera at the sight tube or Cheshire eyepiece and perhaps a monitor at the mirror cell. If alignment is done by watching the screen, there is immediate feedback to the turning of the adjustment nuts. This allows for natural hand-eye coordination so necessary to the task of alignment. Also, consider removing the center dot painted on the center of the mirror and carefully scratch away the mirror coating exactly in the center. A 1/8in or smaller area is enough. Now place the LED (I use the same battery-operated light used to illuminate setting circles) behind the mirror. The bright light makes a great target when collimating the scope, with or without the video camera.

In addition to allowing for good hand-eye coordination, the video camera allows for increased scale during the adjustment. The center dot is now plenty big, and so motion is that much easier to judge. Also, the variable light level of the LED permits good collimation in a variety of lighting conditions.

How well does it work? Most of the time I find that when I drop an autocollimator eyepiece in place to complete the job I find it to be close enough that the play in the position of the eyepiece will indicate good alignment without further adjustment. Autocollimation can be achieved by watching the multiple images of the LED and adjusting until they meet in the center! If this is done, a check with the autocollimator in the usual fashion (with a penlight held inside the open end of the tube) reveals proper alignment.

The technique is accurate, fast and much less frustrating. It may even save friendships!

 

 

 

 

 

 

 

 

 

 

 

 

 

Img 1: Viewed with the video camera at the eyepiece. Img 2: Keep in mind that any track established by turning an adjustment nut will be 120deg to any other