Erratum: “Ultrahigh-energy gamma-ray emission from the Geminga pulsar” [Pis’ma Astron. Zh. 27, 266 (2001); Astronomy Letters 27, 228 (2001)]

Abstract

On page 269, the value with a minus in the left column in line 11 from above should be with a plus.

BL Lac: A new ultrahigh-energy gamma-ray source

“…The effective detection threshold energy of gamma rays is 1.0 TeV. More detailed descriptions of the GT-48 telescope can be found, for example, in [3,8].…”

“…Two AGN were found to be sources of ultrahigh-energy gamma-rays using the 10-m ground Cherenkov detector of the Whipple Observatory in the United States: the Makarian galaxies Mrk 421 and Mrk 501 [2]. At the Crimean Astrophysical Observatory (CrAO), high-energy gamma-rays were also detected from the blazar 3C 66A [3], and classified, like Mrk 421 and Mrk 501, as a BL Lac object; BL Lac is the prototype of this relatively small group of AGN.…”

“…However, in January-February 1995, the flux rose to (4.0 ± 1.2) × 10 -7 photons cm -2 s -1 , providing evidence for variability in the gamma-ray emission from BL Lac. Studies of BL Lac at the CrAO were renewed in 1998 using the second-generation GT-48 gamma-ray telescope [3,8].…”