U Scorpii

U Scorpii

Location of U Scorpii (circled in red)
Observation data Epoch J2000      Equinox J2000
Constellation	Scorpius
Right ascension	16h 22m 30.78s[1]
Declination	−17° 52′ 42.8″[1]
Apparent magnitude (V)	7.5 Max. 17.6 Min.[2]
Characteristics
Spectral type	? / White Dwarf
Variable type	Recurrent nova[2]
Astrometry
Radial velocity (Rv)	65[3] km/s
Proper motion (μ)	RA: −0.380±0.202[4] mas/yr Dec.: −7.591±0.144[4] mas/yr
Parallax (π)	−0.0945[4] ± 0.1334[4] mas[4]
Distance	19600+21000 −5300[2] pc
Other designations
AAVSO 1616-17, Nova Sco 1863, BD−17 4554, Gaia DR2 6246188565119443072, 2MASS J16223079-1752431[3]
Database references
SIMBAD	data

U Scorpii (U Sco) is a recurrent nova system, one of 10 known recurring novae in the Milky Way galaxy.^[5] Located near the northern edge of the constellation Scorpius it normally has a magnitude of 18, but reaches a magnitude of about 8 during outbursts. Outbursts have been observed in 1863, 1906, 1936, 1979, 1987, 1999,^[6] 2010,^[7] and 2022.

The 2010 outburst was predicted to occur April 2009 ± 1.0 year, based on observations during quiescence following the 1999 outburst.^[8] The U Sco 2010 eruption faded by 1 magnitude in 1 day, and by 4 magnitudes in 6 days. By February 6 it was dimmer than magnitude 13. Between February 10–19, it was flickering around magnitude 14. The eruption ended on day 64, which is the fastest observed decline to quiescence of a recurring nova.^[9] This eruption of U Sco became the best-observed nova event to its day, with 22,000 magnitudes accumulated.^[9] Astronomers then predicted that another eruption of U Sco would occur in 2020±2. This prediction was correct: it brightened to +7.8 magnitude on 6 June 2022.^{[citation needed]}

Originally identified as a nova in 1863 by English astronomer N.R. Pogson, U Scorpii was the third nova to be identified as recurrent, by American astronomer and historian of science Helen L. Thomas, in the years preceding World War II.^[10][11]

• http://www.phys.lsu.edu/dept/people/schaefer.html Archived 2009-03-13 at the Wayback Machine
• U Scorpii in Outburst
• Long-term monitoring of the recurrent nova U Scorpii (AAVSO 2010 April 9)
• AAVSO: Quick Look View of AAVSO Observations (get recent magnitude estimates for U Sco)