PSR B1919+21

Provenance-Backed Scientific Measurements

Every measurement below preserves its unit, uncertainty interval, observational method, reference epoch, quality status, and primary catalog source. See Uncertainty & Provenance for how competing measurements are handled.

J2000 Equatorial Sky Chart & Culmination Altitude

The chart below plots PSR B1919+21 (CP 1919) — First Known Pulsar at RA 19h 21m 44.81s, Dec +21° 53′ 02.2″ within Vulpecula, alongside peak meridian transit altitudes for 40°N and 30°S observers. Use the RA/Dec Coordinate Converter to compute exact culmination altitude for your latitude.

Astrophysical Context & Structure

In late 1967, graduate student Jocelyn Bell (now Jocelyn Bell Burnell) was analyzing miles of paper chart-recorder rolls from the 81.5-megahertz Interplanetary Scintillation Array near Cambridge, England, when she noticed a quarter-inch patch of 'scruff' that reappeared every sidereal day at right ascension 19h 19m in Vulpecula. High-speed recordings on November 28, 1967, resolved the signal into a train of sharp radio pulses repeating with clockwork precision every 1.33730 seconds. Jokingly dubbed 'LGM-1' (Little Green Men-1) before three more pulsars were found across the sky, the source was cataloged as CP 1919 (Cambridge Pulsar 1919) and proved the existence of rapidly rotating magnetized neutron stars.

PSR B1919+21 is a middle-aged canonical radio pulsar with a characteristic spin-down age near 15.7 million years and a surface dipole magnetic field of roughly 1.4 trillion gauss. Located about 2,300 light-years away, its radio emission displays classic 'drifting subpulses'—individual sub-components within the 40-millisecond pulse window that march systematically in phase from pulse to pulse as plasma carousels circulate above the neutron star's magnetic polar cap.

Beyond transforming relativistic astrophysics, the stacked radio pulse profile of CP 1919 published in the 1970 Cambridge Encyclopedia of Astronomy became one of the most recognizable graphics in popular culture when graphic designer Peter Saville featured it on the cover of Joy Division's 1979 debut album Unknown Pleasures.

Practical Visual Observing Guide

• Emits exclusively in radio waves and weak X-rays; no optical counterpart is visible in amateur or mid-sized professional telescopes.
• Its 1.337-second pulse period and 40 ms pulse width are steepest at low radio frequencies (80–400 MHz).
• Located in western Vulpecula, roughly 3.5 degrees northwest of the Coathanger asterism (Collinder 399).

Catalog Cross-Identifications & Aliases

Common Aliases: CP 1919 · PSR J1921+2153 · LGM-1

Related Objects, Comparisons & Guides

Scientific Sources & Dataset Provenance

• SIMBAD Astronomical Database (CDS) (2026-10 release): Wenger, M., et al. 2000, A&AS, 143, 9 (The SIMBAD astronomical database) — Centre de Données astronomiques de Strasbourg