Facts about Mrk 501

1. 07

   Optical observations spanning decades reveal that Mrk 501 undergoes brightness variations of up to a factor of 10 on timescales as short as a single day in visible light.

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2. 06

   TeV observations with the MAGIC telescope in 2012 revealed that Mrk 501 produced the highest-energy gamma rays ever detected from an extragalactic source at that time, with photons exceeding 10 teraelectronvolts.

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3. 05

   Mrk 501 was first catalogued by Soviet astronomer Benjamin Markarian in 1974 as an unusual emission-line object before its true nature as a blazar became established.

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4. 04

   Mrk 501's blazar jet points nearly along our line of sight, an alignment that amplifies its observed brightness by a factor of up to 100 through relativistic beaming effects.

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5. 03

   Supermassive black holes power Mrk 501's relativistic jets, which accelerate particles to nearly the speed of light and produce radiation observable across the electromagnetic spectrum from radio to gamma-ray wavelengths.

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6. 02

   Located approximately 465 million light-years away, Mrk 501 is a blazar in the constellation Hercules that varies dramatically in brightness across multiple wavelengths within timescales of hours.

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7. 01

   Gamma-ray observations detected Mrk 501 exhibiting a flare in February 1997 that made it the brightest extragalactic gamma-ray source known at that time.

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