Frankfurt Quasar Monitoring

3C 66A

Object data
  Cross-Identifications   B3 0219+428A, PKS 0219+428, MG4 J022237+4301
  MW 0219+42, 87GB 021932.0+424811, 0219+428
  1ES 0219+428, 2EG J0220+4228, GRO J0222+242
  2E 0219.5+4248, 3EG J0222+4253, NRAO 102
  QSO B0219+428, GB6 B0219+4248, LHE 055
  Equat. coordinates   RA  02 22 39.6     DE  +43 02 08     (J2000)
  Constellation   Andromeda
  Type   BL Lac
  Distance (2) (3)   1646 Mpc
  Total mag range (mv) (4)    12.81 - 16.56
  Catalog Magnitude (1)   15.21
  Absolute Magnitude (1)   -26.5 MB
  Light Travel-Time (2)   4.472 × 109 yrs
(1) Véron-Cetty & Véron 2006, A&A 455, 776
(2) NASA/IPAC Extragalactic Database
(3) Co-Moving Radial Distance
(4) Literature

Finding chart


Comparison stars

star  B V Rc Ic
A --- 12.791 12.701 12.591
B --- 13.601 13.381 13.061
C --- 14.181 13.621 13.101
D 15.0883 14.3323 13.9073 13.5013
F --- 14.771 14.281 13.731
G 15.8333 15.0763 14.6503 14.2263
H 16.2773 15.3093 14.7493 14.2673
K 16.282 15.752 15.312 ---
L 16.772 16.102 15.712 ---
M 17.782 16.902 16.102 ---
N 17.9803 17.2003 16.7783 16.3773
P 18.0283 17.2463 16.7893 16.3693
(1) comparison stars from Fiorucci et al. 1996, A&AS, 116, 403
(2) comparison stars from Craine et al. 1975, PASP, 87, 123
(3) comparison stars from
Gonzàlez-Pérez et al. 2001, AJ, 122, 2055

Colour chart
Credit: DSS2  /  Size 14´× 14´ /  Chart by S. Karge

Light curve


3C 66A is a well-known BL Lac object in the eastern part of Andromeda, only 40´ north of edge-on galaxy NGC 891. The designation 3C 66A refers to the 3rd Cambridge Radio Catalog (3C), where this object was discovered as a radio source in 1959. In 1966, the radio source 3C 66 was found to consist of two different sources: 3C 66A, a stellar object (later identified with the BL Lac object), and 3C 66.0B, the active radio galaxy UGC 1841 (z=0.0215), some 6´SW of 3C 66A (see finding chart).
In 1974, the radio source 3C 66A was identified with a 15-mag stellar object. Despite its (nearly) featureless spectrum a redshift of z=0.444 was determined. This corresponds to a cosmological distance of about 4.5×109 light-years. Since 1974, 3C 66A has been classified as a BL Lacertae-type object. Besides the optical and radio, blazar 3C 66A has been detected also as a source of both X-rays and gamma rays.

As for most BL Lac objects, also 3C 66A shows fast and violent flux variations, ranging between 13 mag and 16 mag in the optical. On average, the brightness ranges between 14 mag and 15 mag (see light curve above). CCD observers, as well as visual observers, shall use the comparison stars given above. Other sequences were published by Smith et al. (1998) and the AAVSO. For visual observers, 3C 66A is one of the most interesting blazars in the night sky. A telescope of 8- to 10-inch of aperture and larger will show this blazar as a stellar object. At maximum brightness, even a 6-inch telescope will make 3C 66A visible in the eyepiece.

Right next to 3C 66A there are 3 UGC galaxies, adorning this section in the sky: UGC:1832 (NW), UGC:1837 (SE) and UGC:1841 (SE). This galaxy trio is part of galaxy cluster Abell 347, located in the cosmological foreground of 3C 66A. A few arcseconds SE of UGC 1841, the finding chart above also shows the 15-mag compact elliptical galaxy V Zw 230 = LEDA 212964. Finally, do not forget about showpiece galaxy NGC 891 (40´S) and the adjacent galaxy cluster Abell 347, centered on NGC:910, SE of 3C:66A.

Another bright source of very old quasi-stellar photons, quasar RXS J00066+4342
, is a bright 14-mag object at a distance of about 2×109 light-years, located 24.5° west of 3C 66A.

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Landessternwarte Heidelberg (1)

Landessternwarte Heidelberg (2)

Hamburg Quasar Monitoring


Gary Poyner (light curve)

© Stefan Karge (FQM)  /  last obs. 2024-06-21