Markarian 421

Also known as Mrk 421

Markarian 421 is a BL Lac in the constellation Ursa Major, about 414.77 million light-years from Earth.

Nearby blazar, a bright source of very high-energy gamma rays

Open it on the live sky map Plan Night Exploration

Markarian 421: a sky-survey photograph of its field — Sky survey view (DSS2 colour, or a backup survey)

Facts

Type	BL Lac
Constellation	Ursa Major
Position (J2000)	11h 04m 27s, +38° 12′
Distance	414.77 million light-years (its light set off about 414.77 million years ago)
Brightness	magnitude 12.9 (smaller is brighter; the faintest stars the eye sees are about 6)
Size on the sky	0.6′ × 0.5′ (the full Moon is about 31′)
Redshift	z = 0.03
Studied in	2,874 scientific papers (SIMBAD)

When and how to see it

Markarian 421 is highest in the sky at midnight in March. From India (about 20° N) it climbs to about 72° above the horizon; from 50° N, to about 78°. To see it you need a large telescope or long-exposure photos.

Heights are worked out for India and for 50° N. Set your location in Settings to see them for where you are.

For tonight's best time from your own town, the darkness and the Moon, open it on the map and see its "Tonight from your location" card.

More in Ursa Major

Everything in Ursa Major · All 88 constellations · All sky objects

Data: SIMBAD (CDS, Strasbourg; the site's weekly copy) · Data sources & credits