An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A region in the sky lying roughly between the → pointer stars of the → Big Dipper that is almost free from → neutral hydrogen gas in the → Galaxy. It is centered at R.A. 10h 45m, Dec. +57° 20', has an area of 15 square degrees, and a → column density of N_{H I} ≤ 5 x 10¹⁸ cm^-2. The Lockman hole is one of the favorite directions for obtaining a clear and unobstructed view of objects in deep space, far beyond our own Galaxy.

Named after Felix J. Lockman et al., 1986, ApJ 302, 432; → hole.

The aggregate of all possible positions of a moving or generating element, e.g. the locus of points equidistant from a given point is a circle whose center is the given point.

From L. locus "place," from Old L. stlocus, literally "where something is placed," from PIE base *st(h)el- "to cause to stand, to place."

Mahalgân, from mahal "place, locality" + -gân relation and multiplicity suffix.

A rare type of → achondrite→ meteorite.

Named after Lodhran (Punjab), Pakistan, where the type specimen fell on 1 October 1868.

A low frequency radio telescope network concentrated in the Netherlands with extensions into other European countries. It consists of a core and an extended → array in the Netherlands as well as in surrounding European countries with maximum → baselines of 2 km, 100 km, and 1,000 km respectively. LOFAR will be the largest radio telescope ever built, using a new concept based on a vast array of simple omni-directional antennas. The array will operate at the lowest frequencies that can be observed from Earth, at 30-250 MHz. About 75% of the construction is finished and LOFAR has already started its → commissioning period. When entirely finished, it will consist of 45,000 small antennas, distributed within 48 stations in the north east of the Netherlands, nearby parts of Germany, the UK, France, Sweden, and perhaps later Poland and Spain. The extensions in the United Kingdom, Germany, and France are completed. The French extension, located in the Nançay station of Paris Observatory (190 km south of Paris), is fully operational since December 2010. Moreover, a project to extend the low-frequency component of the Nançay station is under study. LOFAR is a forerunner of the future → Square Kilometer Array (SKA) project. See also the LOFAR homepage.

LOFAR, short for → LOw; → Frequency; → ARray.

1) Any of various records, made in rough or finished form, concerning a trip made by a ship or aircraft and dealing with particulars of navigation, weather, engine performance, discipline, and other pertinent details; → logbook.
2) To enter in a log; compile; amass; keep a record of (Dictionary.com).

M.E. logge, variant of lugge "pole, limb of tree; piece of wood," of unknown origin, back formation from logbook, a book used by sailors to record the speed measurements made by means of a chip of a tree log on the end of a reeled log line.

1) Log, loan from E., as above.
2) Logidan, infinitive from log.

Computers: To enter identifying data, as a user name or password, into a database, mobile device, or computer, especially a multi-user computer or a remote or networked system, so as to to access and use it (Dictionary.com).

→ log; → in.

Computers: To terminate a session.

→ log; → out.

The → exponent of the → power to which it is necessary to raise a fixed number to produce the given number. The fixed number is called the → base. The logarithm of x to the base a, denoted log_a(x), is the unique → real number  y such that a^y = x. In the familiar system of → common logarithms, the base is 10. In the system of → natural logarithms, the base is e = 2.7182818 ... (→ number e). For example, the logarithm of 100 (base 10) is 2 because 10² = 100.

Mod.L. logarithmus, coined by Scottish mathematician John Napier (1550-1617), literally "ratio-number," from Gk. logos "proportion, ratio, word," → logic + arithmos "number," → arithmetic.

Of or pertaining to a → logarithm.

→ logarithm; → -ic.

Same as → reddening coefficient.

→ logarithmic; → extinction.

A scale of measurement in which an increase of one unit represents a tenfold increase in the quantity measured (for common logarithms)

→ logarithmic; → scale.

A book in which details of a trip made by a ship or aircraft are recorded; log (Dictionary.com).

→ log; → book.

1) The science that investigates the principles governing correct or reliable inference.
2) The system or principles of reasoning applicable to any branch of knowledge or study.
3) A particular method of reasoning or argumentation.

M.E. logik; O.Fr. logique, from L. (ars) logica, from Gk. logike (techne) "reasoning (art)," from feminine of logikos "pertaining to speaking or reasoning," from logos "reason, idea, word."

Guyik, from guy- present stem of goftan "to say, speak, relate, tell; to compose a poem," from Mid.Pers. guftan "to say, tell, utter;" O.Pers. gaub- "to say" + -ik, → -ic.
Cemguyik, from Mid.Pers. cimgôwâgih "logic," from cim "cause, reason, meaning" (Proto-Iranian *cahmāt "what for;" cf. Skt. kasmāt "why, where from," kim "what") + gôwâgih Mod.Pers. guyi, as above.

A diagram that uses special symbols called logic symbols to represent the detailed functioning of electronic logic circuits. The symbols do not represent the type of electronics used, but only their functions.

→ logic; → diagram.

1) According to or agreeing with the principles of logic.
2) Reasoning in accordance with the principles of logic, as a person or the mind.
3) Of or pertaining to logic (Dictionary.com).

→ logic; → -al.

A symbol that can be combined with one or more → sentences in order to form a new sentence. For example "and" (∧), "or" (∨) "not" (¬), "if-then" (→), and "iff" (⇔).

→ logical; → connective.

Describing two → compound propositions → if and only if they have the same → truth table.

→ logical; → equivalent.

1) The act of logging in to a database, mobile device, or computer, especially a multi-user computer or a remote or networked computer system.
2) A user name and password that allows a person to log in to a computer system, network, mobile device, or user account (Dictionary.com).

→ log; → in.

A → probability distribution in which the natural logarithm (logX) of the → random variable (X) has a → Gaussian distribution.

→ logarithm; → normal distribution.

The process by which a computer user logs out.

→ log; → out.