ATM 20": first light

[Hugues_Laroche@ses-astra.com]

Yahoo!

Yesterday evening I completed my 20", whatever it means... I am
probably particularly thick and slow: what an amount of time
the building of such a scope requires! Also, to all big-dob-builders-to-be:
be warned that an assembled scope is bigger than what you would
expect when handling the mirror alone! That does not say "dont do
it", just be prepared for a certain form of surprise.

Sooo. It is a 500mm diameter (so not exactly 20") f/4.2; it is not correctly
collimated so far, so I guess that's why M13 was a bit deceiving: the stars
hardly resolved. The effect of bad alignment was quite visible on brighter
stars. But I could see M57 much more intense than with the 10", it
was marvelous! Not speaking about the moon, which spoiled more than
half of the sky.

A nuisance: the scope is considerably bottom-heavy. OK, it is easier
to cure than the inverse. Still need to baffle the sec. cage and put
a shroud around the truss.

And, finally, the truss should still be shortened a bit: only a 30mm
eyepiece pushed to the max. towards the secondary could focus :-(
Once corrected, it will agravate my bottom-heavy problem BTW
(normal, if one take Murphy's law into account).

It is such a marvelous moment when looking for first time through an
instrument you have done with your hands (well, with some tools too ;-)!
It has been said several time, and although if I experienced it already
myself, it remains nearly magical. Sorry to take a bit of bandwidth with that.

To make it, I am in debt of help from Mel for figuring,
Richard Schwartz for an unequal loads cell computation,... and many many of
you, directly or indirectly. I have still not motorised it yet (sorry Andy!).
Thanks to all (and Mr Texereau!)... just wished I had know this list earlier (I
would
have ordered a blank of better quality, in particular)!

Still need tracking, a CCD and a web site and I hopefully can supply pictures
too
(not tomorrow, seemingly)

A bit euphoric...

Hugues