In infrared astronomy, the J band refers to an atmospheric transmission window (1.1 to 1.4 Ξm) centred on 1.25 micrometres (in the near-infrared).
Betelgeuse is the brightest near-IR source in the sky with a J band magnitude of â2.99. The next brightest stars in the J band are Antares (â2.7), R Doradus (â2.6), Arcturus (â2.2), and Aldebaran (â2.1). In the J band Sirius is the 9th brightest star.