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Observation Date (UT) Observation Lat

Canonical Name:Markarian 421
TeVCat Name:TeV J1104+382
Other Names:PG 1101+385
B3 1101+384
RBS 0939
RGB J1104+382
1ES 1101+384
1H 1104+382
H 1105+38
3FGL J1104.4+3812
2HWC J1104+381
Source Type:HBL
R.A.:11 04 19 (hh mm ss)
Dec.:+38 11 41 (dd mm ss)
Gal Long: 179.88 (deg)
Gal Lat: 65.01 (deg)
Distance: z=0.031
Flux:0.3 (Crab Units)
Energy Threshold:500 GeV
Spectral Index:2.2
Discovery Date:1992-08
Discovered By: Whipple
TeVCat SubCat:Default Catalog

Source Notes:

Source position and its uncertainty:
From Albert et al. (2007):
- R.A. (J2000): 11 04 19
- Dec. (J2000): +38 11 41
- syst. uncertainty: 2'
- this is consistent with the source position provided by NED

The flux from Markarian 421 is highly variable.
From Ahnen et al. (2016):
Commenting on observations taken with MAGIC between March 2007 and
June 2009:
- "The flux above 400 GeV spans from the minimum nightly value of
1.3 +/- 0.4 10e-11 cm-2 s-1 to the maximum flux, that is about 24
times higher, at 3.1 +/- 0.1 10e-10 cm-2 s-1"

Spectral Index:
The spectral index has been found to vary.
From Albert et al. (2007):
- 2.20 +/- 0.08
- the spectrum shows evidence for an exponential cutoff (independent of EBL absorption)

Information on the jet:
From Lister et al. (2019):
- "All three innermost jet features of this nearby BL Lac object show
inward motion."

Seen by: Whipple, HEGRA, CAT, H.E.S.S., MAGIC, Milagro, Telescope Array, CANGAROO, TACTIC, ARGO-YBJ, HAGAR, FACT, VERITAS, HAWC
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