The Camera Oscillation Monitor:
Because of the short integration time (< 70 ns) for taking a picture
of an air shower, we have the possibility to correct for oscillations
of the PMT-Camera. Oscillations down to the range of the width of half
a PMT (1.5 cm) are relevant.
With the Camera Oscillation Monitor
we want to find out, wether the PMT-Camera is moving regarding
to the reflection of the sky.
How does CaOs work?
For the Camera Oscillation Monitor 6 leds are fixed in a circle at the PMT-Camera
(all with the same distance to the camera center). A standard video camera
is mounted on the dish of the telescope to monitor the movement of the leds
and such the movement of the PMT-Camera.
With the CaOs-software the movement of the center of the PMT-Camera is
calculated from the pictures of the video camera:
There are several algorithms: one filters all bright spots in the picture,
the next filters the leds from other bright spots (reflection, stars, etc.)
by position or distance between the leds. The next algorithm calculates circles
out of the positions of the leds: As a circle is determined by 3 points,
we get 20 circles taking all combinations of 3 leds out of 6, which
gives us good statistics. Averaging all pictures of a dataset, in which
the telescope is not moving, we get the resolution of the radius, the
coordinates of the ringcenter and the rotation angle. Displaying the
coordinates and the rotation angle versus time gives us the movement of
Some useful information, when you want to run the Camera Oscillation
Instructions & Current Status
some preliminary tests with former, temporary
any questions or remarks?
mailto: Daniela Dorner