ASGARD Guided Mode

In addition to running an all-sky camera, the ASGARD software is also capable of detecting meteors in image-intensified imagery and controlling an optical-scanner (galvanometer + mirror tracking system) so that a second camera will follow the meteor in realtime.

Importance

Running ASGARD in guided mode on the correct hardware permits a wide range of studies, some of which are not possible with traditional video recordings:
  • Automatic measurement of the daily meteoroid flux
  • Determination of the mass and velocity distributions
  • High precision studies of fragmentation, wake, and deceleration
  • Study of atmospheric turbulence
  • Understanding and contraining instrument biases
  • direct comparisons with infrasound and back-scatter radar
  • Highly accurate orbit determinations for meteoroid stream modeling
The high precision and accuracy comes from the fact that with the right optics, a per-pixel scale of ~10 metres can be achieved.

Camera Hardware

The Canadian Automated Meteor Observatory (CAMO) is the first implementation to use the ASGARD software in guided mode. It is a project being run by Margaret Campbell-Brown and Paul Wiegert. The specifics of the hardware is summarised here:
  • two Imperx VGA-110L CameraLink CCDs
  • two ITT NiteCam 380 Gen-III intensifiers
  • EDT PCI DV FOX framegrabber
  • UEI PD2-AO-8/16 PCI DAC card
  • Fujinon 25mm f/0.85 lens
  • ZenithStar II ED APO. 80mm f/6.8 doublet telescope
  • Cambridge Technology Optical Scanner
  • Garmin GPS 18x LVC timebase


Detection Algorithm

The detection algorithm while running in guided mode is very similar to the one in all-sky mode, however the detection thresholds are dynamically computed to account for shot-noise present in the image-intensified imagery. With the above listed hardware, ASGARD is able to detect meteors down to magnitude +5.5 (and can calibrate against stars visible to magnitude ~+7.5).

Calibration

Being able to guide the narrow field camera to look at a specific area in the wide field requires calibrating the hardware positioning. This is done by scanning out narrow field images which are rotated, scaled, and combined to give a mosaic. Matching stars can be found, and a plate mapping made.