J/A+A/406/L9 TeV Gamma-Rays from 1ES1959+650 (Aharonian+, 2003)
Detection of TeV Gamma-Rays from the BL Lac 1ES1959+650
in its low states and during a major outburst in 2002.
Aharonian F., Akhperjanian A., Beilicke M., Bernloehr K., Boerst H.-G.,
Bojahr H., Bolz O., Coarasa T., Contreras J.L., Cortina J.,
Denninghoff S., , Fonseca M.V., Girma M., Goetting N., Heinzelmann G.,
Hermann G., Heusler A., Hofmann W., Horns D., Jung I., Kankanyan R.,
Kestel M., Kohnle A., Konopelko A., Kornmeyer H., Kranich D., Lampeitl H.,
Lopez M., Lorenz E., Lucarelli F., Mang O., Meyer H., Mirzoyan R.,
Moralejo A., Ona-Wilhelmi E., Panter M., Plyasheshnikov A., Puehlhofer G.,
delosReyes R., Rhode W., Ripken J., Robrade J., Rowell G., Sahakian V.,
Samorski M., Schilling M., Siems M., Sobzynska D., Stamm W., Tluczykont M.,
Vitale V., Voelk H.J., Wiedner C.A., Wittek W.
<Astron. Astrophys. 406, L9 (2003)>
=2003A&A...406L...9A 2003A&A...406L...9A
ADC_Keywords: Gamma rays ; BL Lac objects
Keywords: gamma rays: observations -
BL Lacertae objects: individual: 1ES1959+650
Abstract:
TeV gamma-rays from the BL Lac object 1ES1959+650 have been measured
during the years 2000 and 2001 with a significance of 5.2σ at a
value of 5.3% of the Crab flux and in May 2002 during strong outbursts
with >23σ at a flux level of up to 2.2Crab, making 1ES1959+650
the TeV Blazar with the third best event statistics. The deep
observation of 197.4h has been performed with the HEGRA stereoscopic
system of 5 imaging atmospheric Cherenkov telescopes (IACT system).
1ES1959+650 is located at a redshift of z=0.047, providing an
intermediate distance between the nearby Blazars Mkn 421 and Mkn 501,
and the much more distant object H1426+428. This makes 1ES1959+650 an
important candidate of the class of TeV Blazars in view of the
absorption of TeV photons by the diffuse extragalactic background
radiation (DEBRA). The differential energy spectrum of 1ES1959+650
during the flares can be well described by a power law with an
exponential cut-off at (4.2(+0.8-0.6)stat±0.9sys) TeV and a
spectral index of 1.83±0.15stat±0.08sys, while the low state
spectrum can be fitted by a pure power law with a spectral index of
3.18±0.17stat±0.08sys.
Description:
The diurnal integral flux values of 1ES1959+650 above 2TeV as
observed in the years 2000, 2001 and 2002 with the HEGRA stereoscopic
system of 5 imaging atmospheric Cherenkov telescopes is provided in
Table 4. For each night, the mean MJD value of the HEGRA observations
is given, together with the duration of the HEGRA measurements (in
hours), the integral flux value (in 10-12phot/cm2/s), the error
of the integral flux (in 10-12phot/cm2/s), and the start and
ending times of the HEGRA observations (given as MJD). In case of no
positive excess detected during a night, an upper limit on the
integral flux above 2TeV is given (at 99% confidence level) marked as
a negative flux value and error equal 0.
Objects:
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RA (2000) DE Designation(s)
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19 59 59.85 +65 08 54.6 1ES 1959+65.0 = JVAS B1959+650
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 57 127 Diurnal integral flux values of 1ES1959+650 above
2TeV from 2000 to 2002 as measured with the HEGRA
stereoscopic system of 5 imaging atmospheric
Cherenkov telescopes.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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3- 12 F10.4 d MJD Mean MJD value (JD-2400000.5)
of HEGRA observation
14- 18 F5.2 h Duration Duration of HEGRA observation
21- 25 F5.2 10-12/cm2/s Flux Integral flux above 2 TeV (1)
28- 31 F4.2 10-12/cm2/s e_Flux Error on integral flux above 2 TeV (1)
35- 44 F10.4 d MJD1 Start MJD value of HEGRA observation
48- 57 F10.4 d MJD2 End MJD value of HEGRA observation
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Note (1):
A negative Flux value indicates an upper limit of the flux;
its error e_Flux is then set to 0.0
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(End) Niels Goetting [Inst.f.Exp.Physics, Univ. Hamburg, Germany] 14-Aug-2003