ATM RE: atm-digest V1 #3693

["Adam Strachan-Stephens" <adamATstrachan-stephens.com>]

You could consider an artificial star test as per Suiter's star testing
book.  For a 10" f/7 this means providing a source of less than  about
0.15 mm diameter and placing it no less than about 50m away.  The short
range will probably minimise the seeing problems.  The small point
source can be provided by shining a light source onto a Christmas
bauble, amongst a number of different ways.

Adam

> Date: Wed, 21 Jan 2004 22:07:32 -0800
> From: "Art" <mock47@accessbee.com>
> Subject: ATM Star test
> 
> Hi,
> I attempted to star test my freshly polished first mirror 10", F/7.  I
> think
> there was too much air turbulence as the stars I looked at seemed to
> scatter
> their light with no evidence of rings.  I could, however, focus in and
> bring
> the light to a fairly sharp point.  Racking in and out merely created
a
> lot
> of flaring and jumping around. I chose another bright light and found
> myself
> looking at Saturn.  With a 9mm eyepiece Saturn was sharp and quite
round
> and
> I could clearly see the space between the rings and the sides of the
> planet.
> I was surprised to get this clear view with an uncoated mirror. Does
this
> hold promise of a good figure or is it common?
> 
> Art