Blazar PKS 1424-414 (z=1.522) brightening

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Terry Bohlsen
Posts: 191
Joined: Thu Sep 29, 2011 7:40 am

Blazar PKS 1424-414 (z=1.522) brightening

Post by Terry Bohlsen »

Hi All
There was a recent ATel #15525 reporting a brightening of this very distant object up to a mag of R=13.4
I tried to take a spectrum of it using my LISA. It is pretty dim but I could certainly obtained a spectrum. It seems pretty flat but because of the high redshift it is difficult for me to determine even vague lines.
Certainly a z=1.522, this is the furthest out object I have been able to take a spectrum of.

Terry
pks1424-418_20220725_452_TBohlsen.png
PKS1424 418pointing_small.png
PKS1424 418pointing_small.png (545.46 KiB) Viewed 2242 times
PKS1424 418guider.jpg

Posted: Within the last 24 hours
==============================================================================
ATEL #15525 ATEL #15525

Title: Bright optical/GeV-ray flares in Blazars PKS 1424-418 and PKS
1406-076
Author: F. Jankowsky, S. J. Wagner, F. Ait-Benkhali (LSW Heidelberg)
Queries: swagner@lsw.uni-heidelberg.de
Posted: 23 Jul 2022; 23:10 UT
Subjects:Optical, Gamma Ray, >GeV, AGN, Blazar, Quasar

Optical observations of the PKS 1424-418 (z=1.522, White et al., ApJ, 327,
561 (1988)) with the Automatic Telescope for Optical Monitoring (ATOM)
in Namibia reveal this Blazar in a bright optical state. Preliminary analysis
of measurements performed on July 23 2022 (MJD 59783.8) show a peak R
magnitude of 13.4 with 0.1 mag variations within one hour. This is 4.6
magnitudes brighter than the
lowest flux measured during the last 15 years. PKS 1424-418 underwent a
steady increase in brightness by 1.2 magnitudes since July 15, 2022 (MJD
59775.2). The optical flare is 0.9 mag brighter than an earlier outburst
observed in May 2010, with a coincident GeV Gamma-ray flare (ATEL #2613,
Buson et al., AA 569, A40 (2014)).

The flare observed in the optical band coincides with an increase of gamma-ray
flux recorded in the 100 MeV - 500 GeV band with the Fermi-LAT instrument
reaching a level of 3.5 10<sup>-6</sup> cm<sup>-2 </sup> s<sup>-1</sup>
on July 22 2022, exceeding the flux of the 2013 flare which has been
the brightest flare in the LAT band so far.

Optical observations of the Blazar PKS 1406-076 (z=1.494, Wilkes et al.,
PASA, 5, 2 (1983)) with ATOM show this Blazar in a bright optical state.
Preliminary analysis of measurements performed on July 23 2022 (MJD 59783.8)
show a peak R magnitude of 16.2. This is 3 magnitudes brighter than the
lowest flux measured during the last 15 years. PKS 1406-076 underwent a
steady increase in brightness by 1.7 magnitudes since May 24, 2022 (MJD
59723.8). This is the brightest flare recorded with ATOM during the past
15 years.

Further multi-frequency observations of these outbursts are encouraged.

ATOM is a 75cm optical telescope located at the H.E.S.S. site in Namibia.

Fermi-LAT fluxes are available also on the public LAT light curve page.
Terry Bohlsen
Armidale NSW
Australia
Hamish Barker
Posts: 226
Joined: Thu Jun 20, 2019 12:11 am

Re: Blazar PKS 1424-414 (z=1.522) brightening

Post by Hamish Barker »

Nice work Terry.

It is certainly a bit mind boggling to be able to measure something so far away, and to do it with amateur equipment is even more incredible.

If 2SPot is able to take a spectrum with a slightly wider wavelength range by a few hundred angstrom each way, there are two possible absorbtion lines just off both the blue and red ends which were previously used to obtain the indicated redshift measurement.
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