Jordanus

Jordanis Constellation Position on a modern map (CC BY Ultima Thulean)

Jordanus in Jakob Bartsch's Planisphaerium Stellatum 1661

An obsolete Early Modern constellation made from eight unnamed Ptolemaic stars: Alpha and Beta CVn, Alpha, 31 and 38 Lyncis (according to Toomer), and three fainter stars of uncertain identity.

Etymology and History

The extinct constellation "Jordanus Fluvius" or "Jordanis" – the river Jordan – was invented by Petrus Plancius on his 1612 celestial globe. The constellation first appeared in print in the book Usus Astronomicus Planisphaerii Stellati by Jacob Bartsch (1624), as his 26th constellation – "Iordanis" or "Iordanus". In the illustration of "Iordanis" on Bartsch's celestial globe Planisphaerium Stellatum... (1661), the star Alpha Lyncis appears as one of the prominent stars in the middle of the constellation. The extinct constellation also appeared as "Iordan" on Isaac Habrecht's (1628) Planiglobium coeleste et terrestre, "Fluvius Jordanis" in Carel Allard's (1706) Hemisphaerium meridionale et septentrionale planisphaerii coelestis and "Ior-Dan" in Corbinianus Thomas' (1730) Mercurii philosophici firmamentum firmianum. John Barentine (2016) notes that most of the area of Jordanis (and its aliases) was carved up in Hevelius's Lynx, Leo Minor, and Canes Venatici, which were subsequently adopted as constellations by the IAU in the 1920s.

Occurrence in historical maps

• Bartsch, Jacob, 1624, Usus Astronomicus Planisphaerii Stellati, p. 57.
• Habrecht, Isaac, 1628, Planiglobium coeleste et terrestre, Figura I.
• Cellarius, Andreas, 1660, Harmonia Macrocosmica, Plates 24, 25 & 26.
• Royer, Augustin, 1679, Cartes du ciel reduites en quatre tables.
• Coronelli, Vincenzo, 1693 & 1696, celestial globes.
• Allard, Carel, 1708, Planisphaerii Coelestis Hemisphaerium Septentrionale.
• Thomas, Corbinianus, 1730, Mercurii philosophici firmamentum firmianum, Frankfurt/Leipzig.

IAU Working Group Star Names

The name was discussed and approved by the IAU WGSN in 2023. Alpha and Beta CVn are already named (Cor Caroli and Chara), the brightest of the others is Alpha Lyncis, mag. 3.1, but WGSN named in Stellio due to the historical constellation name. As this star is already named ..., the WGSN chose ... (not to apply/ to apply the name to a neighbouring star/ to ...) in the IAU-CSN.