This turned out
to be quite a project. The pine trees in Payson near out house
have grown so much in the past several decades that we can no
longer see this cluster from ground level in the back yard observatory.
To remedy this and get a new shot of this stunning object, I
set up our new Bresser mount on the balcony, which is 14 feet
above the ground on the back of the house. The mount tracks superbly
and a series of 1 minute unguided exposures were taken. Seven
of them out of 30 did not have tree limbs, wood stove vent stacks
or other obstructions - but ALL of them had perfectly round stars.
Here I stacked 7 of the unobscured shots to produce this portrait.
Color balance at
this low elevation is a huge problem, but easy to fix. The cluster
came out deep brown/orange from the low altitude haze. To correct
the lack of blues and greens at this elevation, I first split
the RGB data out as separate channels. Then in Maxim DL, remixed
them at different mix ratios other than the 1:1:1 that is the
current condition. By setting the mix ratios to 1:1.3:2 the blues
and greens were completely restored, and the proper globular
colors became visible.
The six inch with
the coma corrector produces sharp stars across the field, and
no other sharpening or deconvolution is normally required. A
nice history on this instrument - which is quite a collectors
item now - can be found on our web site here.