MAGIC Telescopes observation of the BL Lac objects 1ES 1215+303 and 1ES 1218+304

TL;DR

This paper reports the first detection of VHE gamma-ray emission from 1ES 1215+303 and simultaneous observations of both 1ES 1215+303 and 1ES 1218+304 with MAGIC telescopes, highlighting variability and flaring activity.

Contribution

First detection of VHE gamma-ray emission from 1ES 1215+303 and simultaneous MAGIC observations of both BL Lac objects.

Findings

1ES 1215+303 was detected above 100 GeV in January 2011.

1ES 1215+303 showed flaring activity in VHE gamma-rays.

X-ray flux of 1ES 1215+303 nearly doubled compared to previous observations.

Abstract

The two BL Lac objects, 1ES 1215+303 and 1ES 1218+304, separated by 0.8 degree, were observed with the MAGIC Cherenkov telescopes in 2010-2011. The January 2011 observations resulted in the first detection above 100 GeV of 1ES 1215+303 (known also as ON-325) which has been flagged as a promising Very High Energy (VHE, E > 100 GeV) gamma-ray source candidate by the Fermi-LAT Collaboration in October 2010. The January 2011 observations were triggered by the high optical state of the source, as reported by the Tuorla blazar monitoring program. A comparison with the 2010 data suggests that 1ES 1215+303 was also flaring in VHE gamma-rays. In addition, the Swift Target of Opportunity (ToO) observations in X-rays showed that the flux was almost doubled with respect to previous observations (December 2009). Instead, 1ES 1218+304 is a well known VHE gamma-ray emitter located in the same field of view, which was then simultaneously observed with MAGIC. In this contribution we present preliminary results of the MAGIC observations of these two VHE gamma-ray emitting AGNs.