Maxim DL did not work very well with the Audine as a guide scope - when I would click back to full frame, the driver would crash. Further, Maxim does not seem to use real time thread because while it downloads the image via USB of any camera I have, Maxim freezes! So I revived code I had for my home brewed CCD image processing, added Audine code off the web, nursed it a bit, and voila 3 days later an automatic Audine guide handler linked in with my own dome controller software. When ASCOM slews or pulses the scope, or when the Audine cooling temperature changes sufficiently, it automatically reacquires a target and a dark frame. Fire and forget, all night long! The Audine is a terrific and sensitive camera, I couldn't replace it with an expensive guider.
Came time to purchase a 0.5 meter class, I settled for the 0.35 m (14") Celestron OTA. 2 month after purchase, Celestron released the edgeHD, with 3 times wider flatter focal plane. No matter, I'll mostly be imaging with fastar/hyperstar with replaces the front mirror with a lens assembly for F/2 ultra fast imaging.
Most of the previous equipment was re-used, described here. I designed & machined the extended head German mount (obviates flipping scopes crossing meridian). The 400 lbs mount is rock steady, even while touching the scopes. I reused the lower section of the previous mount as it was adequate. My work horse 8" newtonian serves as guide scope. The entire observatory is remotely controlled: see Movie.
Mount specifications:
- Polar shaft: 3" steel, 0.5" wall, 12" RA gear (1" ACME screw).
- Declination shaft: 2" solid stainless, Byers 9.7" dec gear.
- Thru polar shaft cabling, all equipment on mount.
- Design weight/balance, cost analysis & drawings here
A fish eye view into the dome below (hyperstar + QSI583ws CCD on C14 corrector):
Astronomy: equipment
Updated:Jul 2010
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The Hyperstar comes into its own with the QSI 583ws CCD camera with internal colour filter wheel installed in early 2010. At F/1.9, this system is fast! The Orion nebula saturates in 10 seconds.
Phidgets are extensively used to facilitate control of the dome, mount and scopes. All components are USB (C14 ASCOM focus motor and equipment bay shown in photos):
- Aperture panel actuators (qty 2 on C14, 1 on guide scope)
- RA + Dec intelligent direct drive motors
- RA + Dec 17 bit absolute encoders (FPGA)
- Vacuum pump for CCD (no frost, controlled to 0.1 psi)
- Cooling fluid pump (CCD cameras)
- Audine CCD control
- Audine thermo-electric (controlled to 0.1 deg)
- QSI 583ws CCD camera
- Orion Starshoot CCD
- Dome absolute position (bar code)
- Dome relative position/velocity (encoder)
- C14 Focus motor encoder (80 pulses/turn)
- C14 & guide scope focus motors (PWM speed control)
- In dome IR pan/tilt web cam
- In dome IR lamp
- Dome and slit actuation
- Misc control (Dome cooling fans, flood lighting (CCD flats), etc)
- Misc I/Os: Dome temperature, vacuum pressure, spares
Work (of note) carried out:
- The C14 corrector was heated to 300 F (164 C) in an oven for 30 minutes to liberate the loctite on the baffle tube so the Hyperstar conversion kit could be installed.
- Tested Quatech's USBN-500W USB wireless & Icron Ranger 2104 PnP routers. The Quatech failed on the cameras, but the Icron worked wonderfully. The observatory now runs with the PC in the house; no PC in the dome, no more issues with winter temperatures and summer humidity. The Icron is via a buried CAT6 cable.
Issues and way forward:
- RA worm has 60 arc-sec PE, brought down to 10 with sine + high order PEC: see here - note small dents in worm caused spikes. Problem due to low quality end bearings & collars. Replaced with German bearings and machined threaded locking collars (result here). Will fabricate new worm mount and support using bushings and tighter tolerances in summer '10.
- Design and construction of fiber optic coupled spectrometer
A recent addition to the weather station: the sky quality meter SQM-LE (ethernet), which monitors the quality of the sky background. I've installed it inside a weather, heat and light proof enclosure, complete with power supplies and coax ethernet, to remove any influence from electrical storms since the device is on year around. The readings are in magnitude per arc sec squared, higher indicating a darker sky more conducive to seeing fainter stars. Logged readings are here. The perl script also extract data from the excellent clear sky clock and merges it with the SQM data, which will lead to interesting analysis at a later date.
Work on 1.5 meter wide twin dome shutters began late winter 2010. They're required for the large C14 and N8 German mounted pair.
At left: the shutter structure was most elastic and weak until the cross braces were added, when it became astoundingly stiff - the shutters can support over 300 pounds each despite their 20 pound weight and this before aluminum skinning. It must be so because of snow accumulation over their combined 6 foot span.
At right, the shutters are shown mounted on the framework and rails before painting and aluminum skinning in their fully open position. The entire assembly takes the better part of a two car garage!
I've taken a passion to observing the sun: with a Lunt 60 mm imaging hydrogen alpha (missing backorderd double stacking) and the iOptron Mak90 with a visible light Orion glass solar filter, the pair on an iOptron GOTO mount. Splendid way to laze away on a weekend afternoon. The Mak & GOTO used to be on the previous fork mount as steerable guide scope but was no longer needed with the extended head German mount.
Below, the tractor was used to lift the shutters, a task that proved daunting because of the observatory height. It would have been quite impossible without the tractor. Sadly, the right shutter lower aluminum panel was wrinkled during the lift. The job completed below!
My own dome controller began in 1996, so it's keyboard input only, but does the job. It's linked via ASCOM for the mount, C14 focuser and dome. One day I might put a GUI layer.
