- Selenium is a chemical element; it has the symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elemental state or as pure ore compounds in Earth’s crust. Selenium (from Ancient Greek σελήνη (selḗnē) ‘moon’) was discovered in 1817 by Jöns Jacob Berzelius, who noted the similarity of the new element to the previously discovered tellurium (named for the Earth).
- TCrB Charts and Photometry Tables (aavso.org)
Finding charts with comparison stars and related multicolor photometry tables for different scales of T CrB have been created for your convenience. The comparison star magnitudes reflect the revision of 02 July 2024 AND the July 16 re-introduction of the 102 comparison star on the B and D charts.