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- Rannot, R. C., et al.
(författare)
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TeV gamma-ray Observations of the Blazar Markarian 421 from January to April 2004 with TACTIC Imaging Element
- 2005
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Ingår i: 29th International Cosmic Ray Conference Pune (2005). ; , s. 355-358
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Konferensbidrag (refereegranskat)abstract
- We have observed the blazar Markarian 421 (z=0.031 ) with the TACTIC gamma- ray telescope having thresholdenergy of 1.5TeV at Mt. Abu Rajasthan India from January to April 2004. Observations were made intracking mode for a total of 84(on) /16 (off-source) hours with its imaging element equipped with a 349- pixelPMTs camera. During this period, we nd an evidence of a TeV gamma-ray signal with a statistical signi-cance of 6.8. The differential energy spectrum derived in the energy range 2 - 9 TeV is well represented bya simple power law, with a differential spectral index of 2.800.20.
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- Sapru, M. L., et al.
(författare)
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Threshold energy estimate of the proposed MACE gamma-ray telescope at Hanle
- 2005
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Ingår i: 29th International Cosmic Ray Conference Pune (2005). ; , s. 263-266
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Konferensbidrag (refereegranskat)abstract
- The fact that EGRET detected over 250 objects above 100 MeV while only a handful of sources have beendetected above 100 GeV indicates that there is a good chance of detecting a signicant number of these sources(particularly those which do not show a signature of steepening or cut off up to a few GeV), if the thresholdenergy of ground based telescopes is lowered to20 GeV. In the present study, we report the threshold energyestimate of the MACE (Major Atmospheric Cerenkov Experiment) imaging telescope, proposed to be installedin the campus of Indian Astronomical Observatory at Hanle (32.8N, 78.9E, 4200m asl). The results ofthe Monte Carlo simulations carried out with CORSIKA code, suggest that using a pixel threshold of4peand a nearest neighbour quadruplet trigger,-ray energy threshold of15GeV is achievable by the MACEtelescope. Details of the simulation work for estimating the threshold energy along with results obtained arepresented in this paper.
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- Tickoo, A. K., et al.
(författare)
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A generalized ray-tracing procedure for an atmospheric Cherenkov imaging telescope and optical characteristics of the TACTIC light collector
- 2005
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 539:1-2, s. 177-190
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Tidskriftsartikel (refereegranskat)abstract
- A generalized ray-tracing procedure has been developed, which facilitates the design of a multimirror-based light collector used in atmospheric Cherenkov telescopes. This procedure has been employed to study the optical characteristics of the 3.5 m diameter light collector of the TACTIC Imaging telescope. Comparison of the measured point-spread function of the light collector with the simulated performance of ideal Davies–Cotton and paraboloid designs has been made to determine an optimum arrangement of the 34 spherical mirror facets used in the telescope to obtain the best possible point-spread function. A description of the ray-tracing subroutine used for processing CORSIKA-generated Cherenkov data, required for carrying out Monte-Carlo simulation studies, is also discussed in the paper.
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