ISSN:
1572-9508
Keywords:
altitude-azimuth mounting
;
gamma-ray astronomy
;
TACTIC drive-control system
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract A PC-based drive-control system has been developed for the altitude-azimuth mounted TACTIC γ-ray telescope to control the speed and direction of motion of its 2-axes. Details of various hardware components chosen for the telescope, including hybrid-stepper motor, 16-bit absolute encoder and CAMAC-based programmable stepper motor controller, are discussed in this paper. The telescope-control strategy, based on the position-loop with a proportional type control for the source-seek mode and the on/off type control for the tracking mode, is explained in detail. Some important performance features of the telescope, including its blind-spot size, drive-system backlash and encoder-error compensation, are also presented. The drive system has been extensively field-tested and has been operating satisfactorily during observation campaigns carried out since March 1997 with the TACTIC Imaging Element. A tracking accuracy of ±3 arc-minutes has been achieved. A test report of its performance, with regard to its tracking accuracy on the basis of successful detection of TeV γ-rays from the active galaxy Markarian 501 in April–May 1997, is also presented.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1008090931239
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