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Observation Date (UT) Observation Lat

Canonical Name:OJ 287
TeVCat Name:TeV J0854+201
Other Names:RGB J0854+201,
PKS 0851+202,
3FGL J0854.8+2006
Source Type:BL Lac (class unclear)
R.A.:08 54 49.1 (hh mm ss)
Dec.:+20 05 58.89 (dd mm ss)
Gal Long: 206.82 (deg)
Gal Lat: 35.82 (deg)
Distance: z=0.3056
Flux:0.013 (Crab Units)
Energy Threshold:150 GeV
Spectral Index:3.49
Discovery Date:2017-02
Discovered By: VERITAS
TeVCat SubCat:Newly Announced

Source Notes:

This detection was announced in an ATel by VERITAS on 170205:
"We report the detection of VHE emission (>100 GeV) from OJ 287 with
VERITAS. The source was observed by VERITAS between 1 February and 4
February 2017 (UTC), for a total exposure of 13.0 hours. OJ 287 is an
optically bright quasar, known to display quasi-periodicity with
roughly 12-year optical cycles (Shi et al. 2007), and is believed to
host a binary supermassive black hole (Valtonen et al. 2006). The
VERITAS observations were carried out in response to a rising X-ray
flux, noted in the X-ray light curve measured by Swift-XRT
(Stroh & Falcone 2013);"

Source Position:
The NED position was replaced with that from O'Brien et al. on 170904.
R.A. (J2000): 08h 54m 49.1s +/- 2.2s (stat)
Dec. (J2000): +20deg 05' 58.89" +/- 31.96"(stat)
Systematic uncertainty: < 25"

From O'Brien et al.:
- the flux above 150 GeV corresponds to 1.3 +/- 0.2% that of the Crab
From Mukherjee et al. (2017):
- the flux above 100 GeV corresponds to approx. 3% of that from the
Crab Nebula

Spectral Information:
From O'Brien et al.:
- spectral index: 3.49 +/- 0.28
From Nilsson et al. (2010):
- "The average redshift derived from the 6583 [NII] line is 0.3056 +/-
0.0001, consistent with the earlier redshift z = 0.306 (Miller et al.
1978; Sitko & Junkkarinen 1985). The error in the redshift
represents the internal precision of the measurements without
systematic effects, which are expected to be small because the
wavelength calibration was derived from sky lines exposed
simultaneously with the OJ 287 spectrum"

From O'Brien et al.:
- "OJ 287 is an optically bright quasar located at a redshift of z = 0.306.
Archival optical observations dating back to 1890 (Sillanpaa et al., 1988)
have revealed a ∼ 12 year outburst cycle during which 2 optical
outbursts are observed separated by about 1 year. To explain this
quasi-periodic behaviour and deviations from the 12 year periodicity
(see Valtonen et al., 2011), models consisting of a binary
super-massive black hole (SMBH) system at the core of the AGN have
been invoked."
From Benbow et al. (2017):
- "Its SED has shown HBL-like features (Costamante & Ghisellini, 2002)"

Seen by: VERITAS
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