The MMT AllSky Camera T. E. Pickering

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The MMT All-Sky CameraT. E. Pickering

• Low cost ? 3500
• Wide angle ? 150
• Simple ? No mechanical parts
• Frequently updated ? Every 10 sec

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Camera Hardware
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Computer Hardware
Fiber-isolated Video and RS232 ? Need optical
isolation to protect against lightning ? TeleByte
duplex RS232 fiber modems ? Luxcom OM-7 video
fiber modems ? Better video quality than long run
of coax
Framegrabber FlashBus MV PCI ? Color with lower
noise monochrome mode ? Linux driver and SDK
available
Computer Shuttle SFF PC ? 2.8 GHz Celeron w/1
GB RAM ? Nothing special, just need PCI slot and
enough RAM for movies
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Software

• FlashBus SDK from Integral Technologies used to
  build tools for grabbing and averaging frames
  into FITS images.
• Open source ImageMagick tools used to convert
  FITS images to GIF and PNG, apply markup to
  images, and to create animated GIFs. An animated
  GIF of the 100 most recent frames is created
  whenever a new image is acquired.
• No automatic gain or exposure control on camera
  so master control script must monitor image
  brightness and adjust camera parameters
  accordingly. During the day the automatic iris
  control is sufficient and works well.
• Images are archived into DivX format AVI files at
  sunrise and sunset each day. This format allows
  us to compress 4000 images (1.2 GB) into
  single 12-20 MB files while retaining good image
  fidelity.

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How does it do?
Pretty good during the day....
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Pretty darn good at night....
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Can easily see clouds in the dark....
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Handles the bright moon reasonably well....
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Catches meteors, satellites, and zodiacal
light....
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Sometimes there are surprises....
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Calibrating Image Coordinates

• In the images shown, the red cross denotes the
  pointing position of the MMT.
• First step is to find zenith point in image and
  convert (x,y) to (r,?) within image.
• Then it is easy to map azimuth onto ? (we use
  just a zeropoint offset) and zenith angle onto r
  (we fit a cubic polynomial).

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Radial Distortion in Lens
RMS about the full geometric transformation is
1.2 pixels
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In Summary...

• Our system is pretty cheap The capital cost of
  the equipment was less than 3500 and the
  software requirements are fairly simple.
• Our system is robust It has operated almost
  without hitch for the past 8 months.
• Our system is sensitive At night with a maximum
  8.53 sec exposure and a moderate gain setting the
  system can easily reach 5th mag or fainter in the
  visual.
• Rapid response comes in handy The 10 sec duty
  cycle provides nearly continuous temporal
  coverage. This is helped catch light
  precipitation that might otherwise have gone
  unnoticed.
• See http//skycam.mmto.arizona.edu/ for data and
  movies.