| 1. |
- Dhar, V. K., et al.
(författare)
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ANN based energy estimation procedure and energy spectrum of the Crab Nebula as measured by the TACTIC gamma-ray telescope
- 2005
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Ingår i: 29th International Cosmic Ray Conference Pune (2005). ; , s. 179-182
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Konferensbidrag (refereegranskat)abstract
- A novel energy reconstruction procedure based on the utilization of Articial Neural Network has been developedfor the TACTIC atmospheric Cerenkov imaging telescope to estimate the energy of the primary gammaraysin the TeV energy range. The procedure uses a 3:20:1 conguration of the ANN with resilient backpropagationtraining algorithm to estimate the energy of a-ray like event on the basis of its image SIZE,DISTANCE and zenith angle. The results obtained by using the CORSIKA code simulated data suggest theenergy resolution of the telescope is40for retaining90of the-ray events in a particular energybin which is comparable to the energy resolution of other single element imaging telescopes. Details of theenergy estimation procedure along with results obtained by determining the Crab Nebula energy spectrum inthe energy range 1-16 TeV as measured by the TACTIC telescope are presented in the paper.
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| 2. |
- Godambe, S. V., et al.
(författare)
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Very High Energy Gamma-ray and Near Infrared observations of 1ES2344+514 with TACTIC and MIRO Telescopes
- 2005
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Ingår i: 29th International Cosmic Ray Conference Pune (2005).
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Konferensbidrag (refereegranskat)abstract
- 1ES2344+514 (z = 0.04) is one of the rst BL Lac objects to be reported as an extreme synchrotron blazar withsynchotron peak energy reaching up to 100keV and was discovered as a source of Very High Energy (VHE)gamma- rays by the Whipple group in 1995. Subsequently, it was observed by the HEGRA group in 1997/98and 2002. We have recently (Oct.- Dec. 2004) observed the 1ES2344+514 using the imaging element of theTACTIC array and have collected data for 53 hours in on/off mode. The source was also observed in nearinfrared bands J, H and K, for some nights using NICMOS-3 array mounted on 1.2m MIRO infrared telescope.Such a study is expected to provide clues to the dominance or otherwise of the Compton component. Afterdetailed analysis of the TACTIC data we have placed an upper limit of photons cmsata 3condence level on the gamma-ray ux from the source. In the near infrared band the source shows lowlevel variations without any aring activity.
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| 3. |
- 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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| 4. |
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