within line-of-sight distance
1Line-of-sight propagation — refers to electro magnetic radiation including light emissions traveling in a straight line. The rays or waves are diffracted, refracted, reflected, or absorbed by atmosphere and obstructions with material and generally cannot travel over the… …
2Line of battle — In naval warfare, the line of battle [If the fleet is in front of the flagship it is a line ahead , if behind a line astern .] is a tactic in which the ships of the fleet form a line, end to end. Its origins are traditionally ascribed to the navy …
3Cosmic distance ladder — * Light green boxes: Technique applicable to star forming galaxies. * Light blue boxes: Technique applicable to Population II galaxies. * Light Purple boxes: Geometric distance technique. * Light Red box: The planetary nebula luminosity function… …
4Spectral line — Continuous spectrum Emission line …
5Hydrogen line — For hydrogen lines in general, see Hydrogen spectral series. The hydrogen line, 21 centimeter line or HI line refers to the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This… …
6Mason-Dixon Line — The Mason–Dixon Line (or Mason and Dixon s Line ) is a demarcation line between four U.S. states, forming part of the borders of Pennsylvania, Maryland, Delaware, and West Virginia (then part of Virginia). It was surveyed between 1763 and 1767 by …
7Telescopic sight — Scope redirects here. For other uses, see Scope (disambiguation). View through a 4x rifle scope. A telescopic sight, commonly called a scope, is a sighting device that is based on an optical refracting telescope. They are equipped with some form… …
8Course Setting Bomb Sight — The CSBS Mk. IX mounted in a Fairey Battle. The bomb aimer is sighting through the white ring shaped backsights to the pin shaped foresights (just visible against the armoured cable) and holding the bomb release switch in his right hand. The… …
9Semaphore line — This article is about the communication system using towers with pivoting shutters. For other uses, see Semaphore (disambiguation). For the now closed railway in Adelaide, Australia, see Semaphore railway line, Adelaide. A Chappe telegraph at… …
10Lunar distance (navigation) — For the history of the lunar distance method, see History of longitude. Finding Greenwich time while at sea using a lunar distance. The Lunar Distance is the angle between the Moon and a star (or the Sun). The altitudes of the two bodies are used …
