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HARDWARE SOFTWARE





THE DOME
The observatory dome was manufactured by Exploradome. It is composed of a UV stabilized polyethylene and is maintenance-free and virtually indestructible. All the surfaces and doors have about a 1/2” thickness. Polyethylene is extremely durable. It has a higher impact resistance than fiberglass, aluminum and even steel. It’s coefficient of friction is lower than nylon and comparable to Teflon, making it slippery enough for easy cleanup…..and snow slides right off. The dome sits on an aluminum ring that is supported by wheels which ensures a smooth rotation. The shutter slides up and over the top presenting a good view up to and past the zenith.
The dome drive controls are built off the Foster Systems platform. There is a motorized cog to drive the dome azimuth rotation and a separate motorized cable spool to open and close the upper shutter. The lower shutter is driven by two linear actuators. Both motors and actuators are commanded from the PC.

 

SCOPE/MOUNT

 

The heart of the observatory is a Celestron EdgeHD 1400 OTA. EdgeHD is an aplanatic, flat field Schmidt-Cassegrain telescope that produces aberration-free images across a wide visual and photographic field of view. The optical system was designed to reduce more than just off-axis star coma; it also provides an astrograph-quality flat focal plane all the way to the edge of the field of view. Some other specs:

 

  1. Aperture (mm) 355.6 mm (14 in)
  2. Focal Length 3910 mm (154 in)
  3. Focal Ratio 11
  4. Highest Useful Magnification 840x
  5. Lowest Useful Magnification 51x
  6. Limiting Stellar Magnitude 15.3
  7. Resolution (Rayleigh) 0.39 arc seconds
  8. Resolution (Dawes) 0.33 arc seconds

 

The scope is driven by an Orion HDX-110 EQ-G GoTo Equatorial Mount (aka Skywatcher EQ8). To connect the mount to the PC, an EQDIR cable was manufactured. The cable utilizes the TTL-232 R-3V3 (serial to USB) drivers to connect via the USB interface. The driver converts the mounts serial signals to USB and vice-versa on the return.

  1. Weight rating 110 lbs.
  2. Motor speeds Max slew speed 3.3°/sec
  3. Motor type Microstep driven stepper motors
  4. Periodic Error Correction +/-3 arc seconds (native and w/o PEC)
  5. Right Ascension (RA) and Declination (Dec) worm wheels 8.6″ (219.5mm) with 435 gear teeth
  6. RA and Dec shaft diameter 55mm
  7. Dual encoders and belt drive

 

AP IMAGE TRAIN
There are a few different image train configurations we use depending on the project. The most common setups are

  1. Deep Sky & Photometry
    – QSI640 CCD camera with a Kodak KAI-04022 Mono chip at prime focus
    – Baader LRGB filters driven by an auto filter wheel
    – Sometimes guiding is necessary and a separate tube with a Lodestar CCD is employed
  2. Planetary
    – ZWO 174MM CMOS camera at prime focus
    – Various filters via EFWmini filterwheel
  3. Wide Angle
    – 460EX CCD camera with a Sony IMX174 Mono chip with a Hyperstar lens
    – Astrodon LRGB filters & Narrowband
  4. Spectroscopy
    – Sheylak Lhires Spectrograph
  5. Solar
    – In development

 

COMPUTING ARCHITECTURE
This is a high level network/computing architecture diagram showing the main components and the interconnectivity. There are 2 core hubs. One sits in the observatory itself and from there a harness runs down to a basement where the datacenter lives. There is about 1500′ of cable across 2 servers and 4 switches to make all this work. There is also a dedicated T1 to eliminate any bandwidth bottlenecks. We expose user connections to the observatory using terminal services which provide direct access to virtual machines. Our full software stack is extended off the application server and made available the users. Some of the observatory control systems will be locked to one user at a time (for obvious reasons) while other applications can be run in parallel.

 

OBSERVATORY SERVER
The heavy lifting is performed by a HP Proliant DL380P GEN8 server. This sits atop a 10TB HP NAS file/storage server. The storage will soon be migrated to a hyperconverged solution given the heavy data and processing requirements. We have a couple firewalls in service managed by 4 different gigabit switches. There is a heavy USB/Serial feed due to the end device port requirements making the cabling very unique. We are also roughing-out an iOT framework and hope to migrate all the devices to it in 2018. There is already a cross-device (hardware in-specific) driver platform that everything rides on (ASCOM) so the software requirements of the conversion requires far less than normal.

 

FOCUSING
Event Horizon Crayford on the rear cell (locked primary)
Microfocus & Feathertouch for the post (unlocked primary)
* All focusing is PC controlled

 

ADAPTIVE OPTICS
We have started to design an adaptive optics system but are early in the process as the technologies are very new