Equipment
Originally, all of the images on this site were taken with one of
three telescopes and one (or two) of three cameras. By coincidence, they
were also taken at one of three locations. The telescopes were a homebuilt
10-inch Newtonian on a fork mount, a Celestron CG9 1/4 on a G-9 German
equatorial mount, and a Meade 2045D which is piggybacked on the 10-inch.
The cameras were a Cookbook 245 which I constructed in 1995, a StarlightXpress
MX716 purchased in 2003, and a StarlightXpress MX916 borrowed from my friend
Dennis Webb for a couple of months while my MX716 was in for repair. The
locations were my observatory at West Point, Texas, Prude Ranch at Fort Davis,
Texas (where the Texas Star Party is held), and the Fort McKavett state
historical site (where my astronomy club has regular star parties).
Beginning is 2008, essentially all of the replacement images are being taken
with an SBIG ST2000XM camera.
The
picture at the left shows the observatory with the telescope stored. A very large majority (305) of the
original images were taken
here, and most of those with the 10-inch. All of the TSP and Fort McKavett images were taken with the CG9 1/4. The year after I retired
(1999), we purchased 10 acres of land several miles outside of West Point and
started building a log cabin and the observatory. The observatory consists
of an 8 x 12 prefabricated building, a 12 x 20 deck, and a rolling cover to
house the telescope. The poles at the corners hold tarps to serve as
windscreens when needed. The building has almost all the comforts of home,
including a double bunk, power, water, telephone, TV, heat, A/C, computer, and portapotty. The telescope can be operated either from the deck (in good
weather) or from the building (when it's too hot or cold). The picture
below on the right shows the setup for nice weather. I like to stay
outside as much as possible to enjoy the sky while the images are collecting.
The black box is a cover for the laptop, which protects it and shields the
screen -- essential at star parties and very desirable even if I'm the only one
around. My JMI Accutrac V and Motofocus control just rest on the deck beside my
chair.
The 10-inch telescope was constructed in the late 70's
while I was living in Chicago. The mirror is a full-thickness Coulter
f/5.5 with
a excellent figure. 
It's in a 12 1/2-inch Parks tube with a Novak mirror
cell, spider, and diagonal holder. About half the images were taken while
I was using a 2-inch Meade rack-and-pinion focuser but then I upgraded to a JMI
NGF with Motofocus. That one change made a great improvement in my
productivity and image quality. I built the fork mount in the local high
school shop. The head is 1/2-inch steel plate, with 2-inch
pillow blocks and shaft, and the fork is 2 x 4 x 1/4 steel box with 1-inch
self-aligning bearings. The head is mounted on a 8 inch, 22 1/2 degree
pipe elbow which, in turn, is on a 7 foot by 20 inch diameter concrete pier.
The 11 1/2-inch drive gear was purchased from Aeroquest about 2001 and the
rotating rings were a second-hand purchase at TSP a year or so later. A
Telrad, Orion 9x50 erect-image finder, and a piggy-backed Meade 2045D complete
the setup. I do have setting circles but rarely use them. However, I
purchased an Argo Navis at the 2007 TSP and am using it regularly now to locate
targets. Even though I've been pretty lax about refining my coefficients,
it always puts the object of interest somewhere in the field of my SBIG
ST2000XM.
This
picture is a more detailed view of the equatorial head and drive gear. The
worm and drive motor assembly are pivoted and spring loaded. The two large
bolts at the top of the plate provide the altitude adjustment for polar
alignment. I have a removable push-pull tool for the azimuth adjustment
but have only had to make one touch-up of the alignment in six years.
A
close-up of the declination drive is shown at the right. Since I have a
lathe and milling machine, I feel slightly embarrassed that I haven't made
anything more sophisticated but it works very well and I've never gotten
around to it. It's constructed of hardwood and 1/8-inch aluminum plate.
A 1 rpm Edmunds DC motor drives an 8-32 bolt running in Teflon bearings.
The bolt moves a piece of aluminum plate in a track, and a pin perpendicular to
the plate rides in an adjustable slot in the tangent arm. It was all done
with hand tools before I got the lathe and milling machine.
I
call this device my Flipper. It allows me to flip the Cookbook or SX MX716
cameras into position
for taking images, or flip to the eyepiece position for centering the target
and or taking darks. There is a spring-loaded eccentric on the back side
of the center axle which lets it move very easily but keeps it firmly held in
either position. The eyepiece holder has lateral adjustments for precise
alignment with the camera, and the little brass buttons at the bottom are
adjustable stops. There is a 2-inch brass tube on the back side which fits
the JMI focuser. It can be removed and replaced with a SC visual back when
I'm using it with either of my SC's. With my ST2000XM, the Flipper is no
longer being used. The camera is mounted directly into the focuser and I
find objects either with the finder scope or, more often, my Argo Navis.
Here is the Meade 2045D on its piggyback mount. I
mounted one of the fork arms (the one with declination adjustment) on a spring-loaded
tilt plate. That provides smooth and convenient X-Y centering. It's
shown the way it's used for ST-4 guiding. When used as my short focal
length imaging system, the diagonal and parfocal adapter are removed and
replaced with a focal reducer and the camera. Since I got the Star2000
system for my MX716, I've seldom used the ST-4. It worked well and I
acquired many good images that way, but S2000 guiding was so easy, quick, and
precise that I always used it, even at the cost of doubling my imaging time.
Now I use the ST2000XM and its separate guide chip. The 2045D is no longer
needed as a guidescope and, so far, I have not used it as an imaging scope with
the new camera.
There is not a whole lot to say about my star party
telescope, the Celestron CG9 1/4. I always use it with a 0.63 focal
reducer so the focal length is very close to that of the 10-inch Newtonian. It has been a workhorse and performed
flawlessly for 10 years. I did finally have to send the G-9 equatorial head
back to Losmandy for reconditioning in 2006 when I was no longer able to
adjust it to remove the gear slop. They replaced essentially all the
moving parts quickly and at a reasonable cost. It doesn't have either the
tracking accuracy or the optical quality of my Newtonian, but the differences
are small. The biggest differences in the image quality are that I almost never
get the polar alignment precision in the field that I have achieved with the
permanent pier, and it doesn't have Motofocus.
I built my Cookbook 245 in 1995 and added the Low Dark
Current upgrade in 1997. The camera had very few problems but the power
supply did require regular repair. However, I don't think I lost more than
a night or two of imaging over the eight years it was in use. Most
problems could be fixed fairly quickly. I can still remember the thrill of
seeing the first images pop up on my monitor. My first target was the
Double Cluster. I was imaging through a 60mm finder and was limited to 8
sec. exposures by my tracking -- the finder was on my 10-inch Dob which was on a
homebuilt tracking platform. But there were still a lot more stars than I
could see through the eyepiece.
I purchased a StarlightXpress MX716 camera late in 2003,
several months after I started this project, and most of the images were
acquired with it. The one time it failed, I borrowed Dennis Webb's MX916
while it was being repaired. I've been very happy with it. While it
is certainly not a top-of-the-line camera, it has a great balance of price and
performance. The very small pixels allow me to achieve good resolution
with a modest focal length scope.
In late 2007, I purchased a used SBIG ST2000XM,
with a color filter wheel and AO-7. I've been using it exclusively since
early 2008 but, I'm ashamed to admit, have yet to attach either the filter wheel
or AO-7. That will come someday and you should start to see a few color
images on this site.
With very few special exceptions (like Arp 152,
the Jet in M87), all of my individual exposures ranged from 30 seconds to 4
minutes. Longer exposures show slightly less electronic noise and, for the
same total image time, take up less hard drive space but both of these factors
are becoming insignificant as technology improves. Shorter exposures are
less affected by cosmic ray, meteor, and satellite contamination, guiding error,
wind, blooming or bloating (depending on the type of camera), and operator
error. I've gradually moved from 4 minutes to 1 minute, as a standard.
I occasionally go back to 2 minutes for very faint objects just so I can see the
quality of the individual exposures better on the screen. And when the
wind is so bad that guiding is impossible, I use 30 second unguided exposures
and keep those few that escape the gusts.
Although not really equipment, I should mention my
acquisition software, which is Astroart 3.0 -- a delight to use -- and my starhopping package. I
start with Bright Star Atlas 2000 and the Telrad, then switch to Uranometria and
the 9x50 finder and/or the flipper eyepiece, and end with (normally) 32.5' x 45'
charts printed with Megastar, first using the eyepiece and then 10 second camera images for final positioning.
This process has now been largely eliminated with the use of my Argo Navis and
the ST2000XM, but I still use the Megastar charts to plan my field.