Question: Along with Jocelyn Bell Burnell, who else discovered the PSR B1919+21?
Context: PSR B1257+12 c, alternatively designated PSR B1257+12 B, also named Poltergeist, is an extrasolar planet approximately 2300 light-years away in the constellation of Virgo.  It was the first planet ever discovered outside the Solar System, and is one of three pulsar planets known to be orbiting the pulsar PSR B1257+12. PSR B1919+21 is a pulsar with a period of 1.3373 seconds and a pulse width of 0.04 seconds.  Discovered by Jocelyn Bell Burnell and Antony Hewish on November 28, 1967, it is the first discovered radio pulsar.  The power and regularity of the signals were briefly thought to resemble an extraterrestrial beacon, leading the source to be nicknamed LGM-1 (for "little green men"). PSR B1257+12 C, alternatively designated PSR B1257+12 d and also named Phobetor, is a super-Earth exoplanet orbiting the pulsar PSR B1257+12 approximately 2,315 light-years (710 parsecs, or nearly km) away from Earth in the constellation of Virgo.  It was one of the first planets ever discovered outside the Solar System.  It was discovered using the pulsar timing method, where the regular pulses of a pulsar are measured to determine if there is a planet causing variations in the data. The Crab Pulsar (PSR B0531+21) is a relatively young neutron star.  The star is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was widely observed on Earth in the year 1054.  Discovered in 1968, the pulsar was the first to be connected with a supernova remnant. Sir John Peebles Arbuthnott, PPRSE, FRCPSG, FMedSci, FRCPath (born 8 April 1939) is a Scottish microbiologist, and was Principal of the University of Strathclyde.  He succeeded Lord Wilson of Tillyorn as President of The Royal Society of Edinburgh in October 2011 and was succeeded by Dame Jocelyn Bell Burnell in October 2014. PSR B1937+21 is a pulsar located in the constellation Vulpecula a few degrees in the sky away from the first discovered pulsar, PSR B1919+21.  The name PSR B1937+21 is derived from the word "pulsar" and the declination and right ascension at which it is located, with the "B" indicating that the coordinates are for the 1950.0 epoch.  PSR B1937+21 was discovered in 1982 by Don Backer, Shri Kulkarni, Carl Heiles, Michael Davis, and Miller Goss. Dame Susan Jocelyn Bell Burnell, (born 15 July 1943) is a Northern Irish astrophysicist.  As a postgraduate student, she discovered the first radio pulsars while studying and advised by her thesis supervisor Antony Hewish, for which Hewish shared the Nobel Prize in Physics with astronomer Martin Ryle.  Bell Burnell was excluded, despite having been the first to observe and precisely analyse the pulsars.  Bell Burnell was President of the Royal Astronomical Society from 2002 to 2004, president of the Institute of Physics from October 2008 until October 2010, and was interim president following the death of her successor, Marshall Stoneham, in early 2011.  She was succeeded in October 2011 by Sir Peter Knight.  Bell Burnell was elected as President of the Royal Society of Edinburgh in October 2014.  In March 2013 she was elected Pro-Chancellor of the University of Dublin. PSR J1614–2230 is a neutron star in a binary system with a white dwarf.  It was discovered in 2006 with the Parkes telescope in a survey of unidentified gamma ray sources in the Energetic Gamma Ray Experiment Telescope catalog.  PSR J1614–2230 is a millisecond pulsar, a type of neutron star, that spins on its axis roughly 317 times per second, corresponding to a period of 3.15 milliseconds.  Like all pulsars, it emits radiation in a beam, similar to a lighthouse.  Emission from PSR J1614–2230 is observed as pulses at the spin period of PSR J1614–2230.  The pulsed nature of its emission allows for the arrival of individual pulses to be timed.  By measuring the arrival time of pulses, astronomers observed the delay of pulse arrivals from PSR J1614–2230 when it was passing behind its companion from the vantage point of Earth.  By measuring this delay, known as the Shapiro delay, astronomers determined the mass of PSR J1614–2230 and its companion.  The team performing the observations found that the mass of PSR J1614–2230 is M .  This mass made PSR J1614–2230 the most massive known neutron star at the time of discovery, and rules out many neutron star equations of state that include exotic matter such as hyperons and kaon condensates. PSR B1913+16 (also known as PSR J1915+1606, PSR 1913+16, and the Hulse–Taylor binary after its discoverers) is a pulsar (a radiating neutron star) which together with another neutron star is in orbit around a common center of mass, thus forming a binary star system.  PSR 1913+16 was the first binary pulsar to be discovered.  It was discovered by Russell Alan Hulse and Joseph Hooton Taylor, Jr., of the University of Massachusetts Amherst in 1974.  Their discovery of the system and analysis of it earned them the 1993 Nobel Prize in Physics "for the discovery of a new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation." PSR J1311–3430 is a pulsar with a spin period of 2.5 milliseconds.  It is the first millisecond pulsar found via gamma-ray pulsations.  The source was originally identified by the Energetic Gamma Ray Experiment Telescope as a bright gamma ray source, but was not recognized as a pulsar until observations with the Fermi Gamma-ray Space Telescope discovered pulsed gamma ray emission.  The pulsar has a helium-dominated companion much less massive than itself, and the two are in an orbit with a period of 93.8 minutes.  The system is explained by a model where mass from the low mass companion was transferred on to the pulsar, increasing the mass of the pulsar and decreasing its period.  These systems are known as Black Widow Pulsars, named after the original such system discovered, PSR B1957+20, and may eventually lead to the companion being completely vaporized.  Among systems like these, the orbital period of PSR J1311–3430 is the shortest ever found.  Spectroscopic observations of the companion suggest that the mass of the pulsar is 2.7 formula_1 (solar masses).  Though there is considerable uncertainty in this estimate, the minimum mass for the pulsar that the authors find adequately fits the data is 2.15 formula_1, which is still more massive than PSR J1614–2230, the previous record holder for most massive known pulsar.
Answer: Antony Hewish