Astron. Astrophys. 353, 847-852 (2000)

7. 1ES 2344+51.4

The spectral energy distribution of 1ES 2344+51.4 is shown in Fig. 6. This source was observed by the Whipple group during the winter months of 1995/96 and 1996/97 (Catanese et al. 1998). Whipple detected a flare on December 20th 1995 with a flux of 6.6 ph cm^-2 s^-1 ( 63% of the Crab); the mean flux (excluding the flare emission) during the first winter was estimated as 1.1 ph cm^-2 s^-1 (11% of the Crab). For the period 96-97 an upper limit of 8.2 ph cm^-2 s^-1 (8% of the Crab) was reported (all integral fluxes above 350 GeV).

The flux limit computed from the 1997/1998 HEGRA CT-system data is 2.9 ph cm^-2 s^-1 ( 1 TeV). The smooth curve in the 2-10 keV band (Fig. 5) indicates that the source has been in a low and stable state for 1.5 years. The source was not monitored by the ASM during the winter 1995/1996, therefore, unfortunately, the 2-10 keV activity during the state of VHE-emission could not be examined.

Fig. 5. Light curves computed from data of the ASM/RXTE detector (1.3-12.1 keV) with a binning of five weeks. Observations range from June 1997 to August 1998.

Fig. 6. Spectral energy distribution of the source 1ES 2344+51.4. Data are taken from Catanese et al. 1998 and Qin and Xie 1997: measurements of different periods before and after the 1995/96 winter period (circles), mean flux value of the high state during the 1995/1996 winter period (square) and flux during the 1 day flare observed by Whipple (triangle). The HEGRA CT-system upper limit is shown as a filled symbol while complementary data are represented by open symbols. The black dot indicates the raw limit, the grey one the limit after deconvolution by the CIB absorption (LCDM model by Primack et al. 1999).

© European Southern Observatory (ESO) 2000

Online publication: January 18, 2000
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