Re: TOM1 Flats

[Tom Droege <tdroege2@earthlink.net>]

When I first got the lenses and knew that I was going to have to take them 
apart, I bought special gloves, special lint free wipes, a respirator, and 
was looking for USP chemicals.

Now I just bang the lens out with a two by four, clamp it in the vice, and 
go at it with a Dremmel tool.  Sigh!  Eventually you adopt a practical set 
of operating conditions.  I remind myself of what I saw at Apache Point 
where moths squish themselves all over the mirror.  Then there is the 
mirror somewhere that was shot with a machine gun.  So you lose 5% of the 
light from dirt, and it cuts down on the contrast.  I think there are a lot 
of other places where you lose more and where much less attention will 
bring an improvement.

The stars are rounder because I am slowly getting everything lined up.  Not 
the lenses, but the mount.  Also the improved Declination drive helps.  It 
does not wiggle around anymore.  One big help was Michael Richmond's 
make_list.out table.  This lets me figure out how to rotate the telescope 
to get it pointed north.

The big thing that the flocked paper has done is to cut down on moon 
problems.  I previously got tremendous artifacts from light from the moon 
reflecting off the inside of the lens barrel.  Now this is very much 
reduced.  The difference between taking data when the moon is 15 degrees 
away and 90 degrees away or some such.  Looks like it will work much better 
at this time of the month - about two days from the full moon.

At first glance, the sky brightness is down by a factor of two, and I am 
measuring a half to three quarters of a magnitude fainter.  So the flocked 
paper looks like it will measure more stars.

Tom Droege


At 07:48 PM 4/13/03 +0100, Andrew Bennett wrote:
>On Sat, 12 Apr 2003 16:56:49 +0000, you wrote:
>
> >I just finished taking the flats for TOM1 after the flocked paper.  They
> >look much different.  Tonight will tell if there is a difference.
> >
> >Tom Droege
> >
>Great! I'll bet that the images are better! Hope
>you are looking forward to getting all the rest
>of the lenses apart and together again ...
>
>Are the stars rounder because you have loosened the
>fit of the lens elements so they are not as
>distorted anymore or are the stars more asymmetrical
>because you have ground off bits of lenses and
>mounts and lenses are now more off-centre?
>
>Jeepers - I can just see myself, greasy and gritty
>from putting new bearings in the grape picker,
>sticking a lens in the vice and taking a bit off
>the edge with my trusty hand grinder!
>
>Andrew Bennett, Avondale Vineyard