Sextans · Star Almanack

{% capture constellation_story %} South of Leo lies a faint constellation named for an instrument that once filled part of an observatory. Sextans, the Sextant, recalls the large apparatus used by Johannes Hevelius to measure the heavens. It is easy to imagine the later handheld sextant of a navigator at sea. Hevelius’ instrument belonged to a different setting. The historical illustration shows a substantial structure used by observers working together, with a graduated arc for measuring angular separations. A sextant takes its name from an arc equal to one sixth of a circle. The celestial figure honors the astronomical tool, an instrument whose scale and construction supported careful positional work. The stars did not need to resemble it perfectly for the dedication to make sense. The name also carries the memory of a loss. In 1679 a fire devastated Hevelius’ observatory in Danzig, destroying instruments and much of the material supporting his work. The sextant became one of the things remembered in the constellation he subsequently introduced. His wife Elisabeth belongs in this history. She participated in the observations, and the famous image of the pair at the instrument makes that collaboration visible. Remembering only the male astronomer would leave out someone whose labor helped create the measurements. Sextans appeared in the celestial catalog and atlas tradition completed after Johannes’ death. Its quiet stars preserve the apparatus in a form that a fire could not consume. The observatory instrument was gone; its name and image continued on the map. There is a distant object in the modern constellation that rewards a different kind of measurement. NGC 3115, or Caldwell 53, is a lenticular galaxy. It has a disk and central bulge but lacks the conspicuous arms of a spiral galaxy. Its elongated appearance has earned it the nickname Spindle Galaxy. Through a telescope it is a subdued patch, while observatory images and analysis reveal the structure of a vast stellar system. Like the sextant, modern instruments help turn a visual impression into information that can be compared and tested. Sextans therefore remembers more than an object in a room. It recalls repeated observations, a partnership, a catastrophic interruption and the decision to keep working. A faint region beneath the Lion carries the trace of a very human effort to make reliable records of the sky. ## Sources - [Sextans - All Skies Encyclopaedia](https://ase.exopla.net/index.php/Sextans) - [IAU: Sextans – exopla.net](https://exopla.net/sextans) - [The secret of Sextans | Astronomy.com](https://www.astronomy.com/astronomy-for-beginners/the-secret-of-sextans/) - [Biographical Encyclopedia of Astronomers](https://mathshistory.st-andrews.ac.uk/BEA/hevelius_johann_bea.pdf) - [Caldwell 53 - NASA Science](https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-caldwell-catalog/caldwell-53/) {% endcapture %}{{ constellation_story | markdownify }}