PSR B1620-26 PSR B1620-26 PSR B1620-26 is a binary star system located at a distance of 3,800 parsecs (12,400 light-years) in the globular cluster of Messier 4 (M4, NGC 6121) in the constellation of Scorpius. The system is composed of a pulsar (PSR B1620-26 A) and a white dwarf star (WD B1620-26 or PSR B1620-26 B). As of 2000, the system is also confirmed to have an extrasolar planet orbiting the two stars. The double system ("triple" including the substellar companion) is just outside the core of the globular cluster. The age of the cluster has been estimated to be about 12.2
Gal (unit) of tens to hundreds of milligals (mGal). The gravity gradient (variation with height) above Earth's surface is about 3.1 µGal per centimeter of height (), resulting in a maximal difference of about 2 Gal (0.02 m/s) from the top of Mount Everest to sea level. Unless it is being used at the beginning of a sentence or in paragraph or section titles, the unit name gal is properly spelled with a lowercase g. As with the torr and its symbol, the unit name (gal) and its symbol (Gal) are spelled identically except that the latter is capitalized. Gal (unit) The