Noun
a 60th part of a minute of arc
Source: WordNetthe treasure is 2 minutes and 45 seconds south of here Source: Internet
If a full moon is present, the sky brightness increases to about 18 magnitude/sq. arcsecond depending on local atmospheric transparency, 40 times brighter than the darkest sky. Source: Internet
The amount of airglow and zodiacal light is quite variable (depending, amongst other things on sunspot activity and the Solar cycle ) but given optimal conditions the darkest possible sky has a brightness of about 22 magnitude/square arcsecond. Source: Internet
The angle SDE is one arcsecond ( 1 3600 of a degree) so by definition D is a point in space at a distance of one parsec from the Sun. Source: Internet
These small angles may also be written in milliarcseconds (mas), or thousandths of an arcsecond. Source: Internet
A second of arc, arcsecond (arcsec), or arc second is of an arcminute, of a degree, of a turn, and (about ) of a radian. Source: Internet