|Frankfurt Quasar Monitoring|
|Cross-Identifications|| 1ES 1219+755, MS 1219.6+7535, QSO B1219+7535
1H 1211+762, RX J1221.7+7518, XSS J12206+7509
SWIFT J1222.0+7518, PGC 39975, Markarian 205
IRAS F12195+7535, 1E 1219.6+7535, 1219+755
1RXS J122144.4+751848, 1AXG J122135+7518
|Equat. coordinates||RA 12 21 44.1 DE +75 18 38 (J2000)|
| Distance (2) (3)
|Total mag range (mv) (4)||14.5 - 15.5|
|Catalog Magnitude (1)||15.24|
|Absolute Magnitude (1)||-22.5 MB|
|Light Travel-Time (2)||0.905 × 109 yrs|
205 for short)
is an AGN in the most eastern part of Draco, close to the constellation Camelopardalis. MRK
205 (z=0.07) is located in the far cosmological background of spiral
galaxy NGC 4319 (z=0.006). As a star-like object, MRK 205 is shining
southern spiral arm of NGC 4319. The host galaxy of MRK 205 was classified as a
spiral galaxy of type SBab. Initially,
MRK 205 was recognized as a quasar
Today, it is classified as an AGN. With an absolute magnitude of -22.5 MB
it does not meet the
quasar classification limit.
205 was discovered by the UV-Continuum-Survey run by B.E. Markarian et
al. (MRK), searching for blue galaxies with excessive UV-emission. It
identified as a quasi-stellar object with Seyfert 1-spectrum by
spectral analysis. An accurate redshift was determined in 1970. Besides
the optical, MRK 205 has also been known as a strong X-ray emitter
(1ES, RXJ, 1H, MS, XSS). |
In the days, when the true nature of quasars was still puzzling, MRK 205 became a well known object by the publications of Holton Arp. His idea was that quasars are luminous objects, escaping from ordinary galaxies at high speeds, explaining the high redshifts when moving away from the observer. A mysterious lightbridge between MRK 205 and NGC 4319 was argued to prove the galaxy-quasar connection. But his ideas were later disproved. In fact, MRK 205 is about 900 million light-years away from earth, a lot more than NGC 4319, which is some 10 times closer. This close alignment of a bright foreground spiral and a bright background AGN, observable through amateur telescopes, is unique in the heavens.
MRK 205 is a low amplitude variable object ranging between mag 14.5 and mag 15.5. Visual observers need at least a 10-inch telescope to glimpse this faint stellar object, close to the bright diffuse nucleus of NGC 4319. The spiral arms of NGC 4319 are only visible through very large aperture telescopes under pristine skies (see sketch above). Together with the neighbouring galaxies NGC 4291 (6´NW) and NGC 4386 (16´NE), MRK 205 is a well rewarding target for both visual observers and CCD observers. Observers shall use the comparison stars given above.
Another bright extragalactic variable - at a distance of about 600 million light-years - is MRK 180, which can be found about 6° SE of MRK 205.
|Arp, H. 1971, ApL, 9, 1; A Connection Between the Spiral Galaxy NGC 4319 and the Quasi-Stellar Object Markarian 205.|
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Hamburg Quasar Monitoring
Image from Hubble Space Telescope
Drawing by B. Laville