Fermi and Swift Observations of High Activity in the FSRQ PKS 0502+049
ATel #6425; R. Ojha (NASA/GSFC/UMBC/CRESST), B. Carpenter (CUA/NASA/GSFC), J. Becerra (NASA/GSFC/UMCP/CRESST), F. Krauss (Remeis Observatory & ECAP, FAU Erlangen/Univ. Wuerzburg), D. Gasparini (ASDC/INAF) on behalf of the Fermi LAT Collaboration.
on 28 Aug 2014; 13:22 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)
Subjects: Optical, Ultra-Violet, X-ray, Gamma Ray, >GeV, AGN, Black Hole, Blazar, Quasar
Referred to by ATel #: 6457
The Large Area Telescope (LAT), one of the two instruments on the
Fermi Gamma-ray Space Telescope, has observed increased gamma-ray flux
from a source positionally consistent with the flat spectrum radio
quasar PKS 0502+049. Preliminary analysis indicates that on August
22, 23, and 25 the daily averaged flux (E>100MeV) was (0.9+/-0.2),
(0.7+/-0.2), and (1.0+/-0.3) x 10^-6 ph cm^-2 s^-1 (statistical
uncertainty only) which is up to 34 times its average daily flux from
the 2FGL catalog (Nolan et al. 2012 ApJS, 199, 31). This source last flared in 2013 March (ATel#4858).
Two follow-up target of opportunity Swift observations were made on
August 23 and August 24 for 2.8 and 2.9 ks, respectively. XRT data
were taken in Photon Counting mode. The X-ray spectrum (0.5-10 keV)
can be fit by an absorbed power law model with an HI column density
set to the Galactic value of 8.76x10^20 cm^-2 (Kalberla et al. 2005,
A&A, 440, 775) using the abundances of Wilms et al. (2000, ApJ, 542,
914) and the cross sections of Verner et al. (1996, ApJ, 465,
487). The unabsorbed fluxes were (4.7+-0.8)x10^-12 and
(4.8+-0.8)x10^-12 erg cm^-2 s^-1; while the photon indexes were
1.5+-0.2 and 1.5+-0.2, respectively. These fluxes are about 2.5 times
that observed during the last high state (2013 March; ATel#4858) and about 7
times that observed during a quiescent state (ATel#4905).
Simultaneous Swift/UVOT observations are shown below. Across all
filters the source has brightened between the two epochs with both
epochs being much brighter (1 to 1.5 magnitudes) than a U-band
observation during the last LAT flare and during a quiescent state
(ATel#4905).
Filter   2014-Aug-23   2014-Aug-24
V       16.47+/-0.18   16.20+/-0.06
B       17.00+/-0.11   16.58+/-0.06
U       16.40+/-0.10   15.94+/-0.06
W1     16.62+/-0.11   16.10+/-0.07
M2     16.76+/-0.19   16.40+/-0.07
W2     16.89+/-0.10   16.59+/-0.07
Because Fermi operates in an all-sky scanning mode, regular gamma-ray
monitoring of this source will continue. This source is being added to
the "LAT Monitored Sources" and consequently a preliminary estimation
of the daily gamma-ray flux observed by Fermi LAT will be publicly
available
(link:http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/). We
encourage further multifrequency observations of this source. For this
source the Fermi LAT contact person is Roopesh Ojha
(Roopesh.Ojha@gmail.com).
We would like to thank the Swift Team for making these observations
possible, in particular C. J. Mountford as the Swift Observatory Duty
Scientist.
The Fermi LAT is a pair conversion telescope designed to cover the
energy band from 20 MeV to greater than 300 GeV. It is the product of
an international collaboration between NASA and DOE in the U.S. and
many scientific institutions across France, Italy, Japan and Sweden.