Increased optical and gamma-ray emission of the quasar PMN J2345-1555
ATel #3734; J.-P. Lenain, G. Cologna, S. Kaufmann, S. Schwemmer, S. Wagner (Landessternwarte Heidelberg) on behalf of the ATOM team
on 4 Nov 2011; 12:50 UT
Credential Certification: Jean-Philippe Lenain (jean-philippe.lenain@lsw.uni-heidelberg.de)
Subjects: Optical, Gamma Ray, >GeV, AGN, Quasar, Transient
We report an increased optical activity of the flat spectrum radio quasar PMN J2345-1555 (z=0.621). This source has been monitored at optical wavelengths for the past 3 years with the ATOM telescope. The source was monitored almost every night with ATOM for the last 5 months.
Since October 25, 2011, the source exhibited a gradual increase from m_R= 16.2 to m_R=14.4 on November 3, 2011, which is 4 magnitudes brighter than the faintest measurement ever obtained on this source with ATOM.
Motivated by the increased activity of PMN J2345-1555 in optical data, a preliminary analysis of Fermi/LAT public data indicates that the source reached a gamma-ray (E>100 MeV) flux of (1.5 +/- 0.6) x 10^-7 ph cm^-2 s^-1 (statistical uncertainty only) for data integrated from October 25 to November 1, 2011, which is a factor ~2.3 higher than the averaged flux reported in the Fermi/LAT second source catalogue (Abdo et al., 2011).
A further analysis of Fermi/LAT data from November 2, 2011, 00:00 to November 4, 2011, 01:35 reveals that the source has a flux of (8.8 +/- 1.6) x 10^-7 ph cm^-2 s^-1, and a photon index of Gamma=2.10 +/- 0.12.
Multiwavelength observations during the ongoing activity of this source are strongly encouraged.
