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

An image which is dim, indistinct, or vague in appearance, for instance when the optics is not well-focused or when the seeing is poor. The same as → unsharp image, contrary to → sharp image.

Blurred, p.p. of → blur; → image.

An image made up of several individual images of relatively short exposure times which are added together in order to produce a final image of higher quality.

Co-added, from → co- "together" + added p.p. of → add; → image.

Tasvir, → image; hamafzudé from ham- "together", → com-, + afzudé p.p. of afzudan, → add.

An image obtained using a deep exposure to reveal the weak features of the object.

→ deep; → image.

A device that is commonly used to measure the → seeing at optical astronomical sites. The DIMM delivers an estimate of the → Fried parameter based on measuring the variance of the differential image motion in two small apertures, usually cut out in a single larger telescope pupil by a mask. The DIMM concept was introduced by Stock & Keller (1960, in Stars and Stellar Systems, Vol. 1, ed. G. P. Kuiper & B. M. Middlehurst, p. 138), whereas its modern implementation was first described by Sarazin & Roddier (1990, A&A 227, 294).

→ differential; → image; → motion; → monitor.

Same as → blurred image.

→ fuzzy; → image.

1) In an optical system, the point to which light rays are converged (real image) or from which they appear to diverge (virtual image) after reflection or refraction.
Math.: A number, point, or unique element of a space that corresponds to some other number, point, or unit element.
2) To make an image of; to picture or represent in the mind.

From O.Fr. image, from L. imaginem (nom. imago) "copy, picture, likeness " from stem of imitari "to copy, imitate," from im-, stem of imitare "to copy, imitate" + -ago noun suffix.

1) Vine, from (Sorani) Kurd. vina or vena "image, picture; similar," from vin/ven, variant of bin, present stem of dîtin, Pers. didan "to see, to look;" cf. Taleshi vinde "to see," Tati vindiyan "to see," Persian bin-, didan "→ see." The relation between "image" and "see" is probably from the fact that the image of a subject can be seen without its presence.
Tasvir, loan from Ar.
2) Infinitive with gereftan "take," → take, and dâštan "to have, to hold," → property.

The process of adding several usually low-exposure images to create an image having a significantly higher signal/noise ratio.

→ image; → co-; → add.

A technique using a mathematical model of the blurring process to recover the original, sharp image. See also → blurred image.

→ image; → deburring.

The meeting of light rays emanating from an object after crossing an optical system.

→ image; → formation.

Device that produces an observable image that is brighter at output than the image at input.

→ image; → intensifier.

The plane in which is formed an image produced by an → optical system.

→ image; → plane.

One of the points constituting an extended image formed in an → optical system.

→ image; → point.

The use of techniques to produce, extract, identify, and display images for evaluation, interpretation, and further interaction with the data.

→ image; → processing.

1) The degree of visibility of relevant → information in an image.
2) The → full-width at half-maximum of a long exposure stellar image obtained by an instrument mounted on a telescope observing in the presence of → seeing.

→ image; → quality.

The separation between two detached but adjacent points in an image.

→ image; → resolution.

The process by virtue of which the original image can be created by removing the blurring and the noise that occur during image formation.

→ image; → restoration.

The quantity that relates the length on the image to the angular or physical separations on the sky.

→ image; → scale.

In an → optical system, the space defined by the totality of → image points. The corresponding points in image space and → object space are called → conjugate points.

→ image; → space.

A device for amplifying faint images by electronic means. Electrons, released when the incident radiation forms a pattern on a photocathode, are accelerated by a magnetic field so that they form a second, brighter image when they strike a phosphor screen.

→ image; → tube.

An electronic device which records images.

→ image; → -er.