261 Prymno is a somewhat large Main belt asteroid. It is classified as a B-type asteroid and probably has a primitive composition not unlike common C-type carbonaceous asteroids.

It was discovered by C. H. F. Peters on October 31, 1886, in Clinton, New York and was named after the Greek Oceanid Prymno.

• The Asteroid Orbital Elements Database
• Minor Planet Discovery Circumstances
• Asteroid Lightcurve Data File

• Lightcurve plot of 261 Prymno, Palmer Divide Observatory, B. D. Warner (2009)
• Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• 261 Prymno at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 261 Prymno at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters