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

Gk., from autos "self, one's own," of unknown origin.

Xod-, from xod "self," Av. hva- "self, own."

1) In radio astronomy, a process performed by an → autocorrelator.
2) In statistics, a linear relation between values of a random variable over time.
3) In electronics, a technique used to detect cyclic activity in a complex signal.

Autocorrelation, from → auto- "self" + → correlation.

Xod-hambâzâneš, from xod- "self" + hambâzâneš, → correlation.

A mathematical function that describes the correlation between two values of the same variable at different points in time.

→ autocorrelation; → function.

In radio astronomy, a spectrograph which correlates the signal with itself with various time delays, and extracts the frequency spectrum of the signal. → correlator.

Autocorrelator, agent n. from → autocorrelate + → -or.

Xod-hambâzângar, agent n. from xod-, → auto-, + hambâzângar, → correlator.

The → covariance of a → time series overt time.

→ auto-; → covariance.

The autocovariance function (ACF) is defined as the sequence of covariances of a stationary process.
A mathematical function that expresses the autocovariance of a series in terms of the interval of separation.

→ autocovariance; → function.

An electronic equipment used to automatically guide a telescope during long exposures.

Autoguider from → auto- "self" + guider, from O.Fr. guider "to guide, lead, conduct," from Germanic origin; akin to O.E. wltan "to look after" witan "to know," akin to O.H.G. wizzan "to know," L. videre "to see," Gk. eidenai "to know," idein "to see," Av. vaêd- "to know," Skt. veda "knowledge; finding."

Xodrâhbar from xod-, → auto + râhbar "guide," from râh "way" + bar, from bordan "to lead."

The act or process of guiding a telescope automatically.

→ autoguider.

Having a self-acting or self-regulating mechanism.

From Gk. automatos "self-acting," from → auto- + matos "willing," from PIE *men- "to think;" compare with Av./O.Pers. man- "to think."

Xodkâr from xod-, → auto-, + kâr "acting, actor," from kardan "to do, act."

A telescope developed to perform photometric observations automatically.

→ automatic; → photometric; → telescope.

An → isomorphism between an → object and itself.

→ auto-; → morphism.

1) Self-governing; independent; subject to its own laws only; having autonomy.
2) Pertaining to an autonomy, or a self-governing community.
3) Biology: Existing and functioning as an independent organism. Growing naturally or spontaneously, without cultivation (Dictionary.com).

Adjective from → autonomy.

1) Independence or freedom, as of the will or one's actions.
2) The condition of being autonomous; self-government or the right of self-government (Dictionary.com).

→ auto-; → -nomy.

An instrument used to test lenses by utilizing the → optical transfer function. It consists of a HeNe laser, a beamsplitter and two mirrors.

→ optical; → autocorrelator.

1) Needless repetition of an idea, especially in words other than those of the immediate context, without imparting additional force or clearness, as in "lifeless dead."
2) A → proposition that is → always  → true. On a → truth table a tautology is a → sentence that is true for every possible → truth value of its constituent parts.

L.L. tautologia "representation of the same thing in other words," from Gk. tautologia, from tautologos "repeating what has been said," from tauto "the same" (contraction of to auto "the same," from to "the" + → auto + -logos "saying," related to legein "to say," → -logy.

Hamân "same" (Mid.Pers. ham "same; also; together," → com-) + ân "that."