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

Same as → altazimuth mounting.

→ altitude; → azimuth; → mounting.

A method used to determine the size of certain types of pulsating stars, including Cepheids, from their magnitude variations (photometry) and the corresponding radial velocities (spectroscopy).

Baade, from Walter (Wilhelm Heinrich) Baade (1893-1960), German/American astronomer, who made important contributions to the research on variable stars; Wesselink, from Adriaan J. Wesselink (1909-1995), Dutch/American astronomer, the originator of the method. → method.

A prefix occurring in loanwords from L. to indicate:
1) Opposition, reversal: decentralize, decode, deactivate, de-emphasis.
2) Removal from: dethrone.
3) Reduction, degradation: declass, devalue.
4) reversal: detract, detect.
5) Derivation from: derive, deverbative.

M.E., from O.Fr. de-, des-, partly from L. de- "from, down, away," and partly from L. → dis-.

Prefix vâ- denoting "reversal, opposition; separation; repetition; open; off; away," variant of bâz-, from Mid.Pers. abâz-, apâc-; O.Pers. apa- [pref.] "away, from;" Av. apa- [pref.] "away, from," apaš [adv.] "toward the back;" cf. Skt. ápāñc "situated behind."
Foru- "down, downward; below; beneath," Mid.Pers. frôt "down, downward," O.Pers. fravata "forward, downward," Skt. pravát- "a sloping path, the slope of a mountain."

Transition from an excited energy state to a lower energy level, as in spectral line formation or particle emission from an atomic nucleus.

From → de- + → excitation.

To cause a spacecraft to leave its operational orbit to enter a descent phase or to change course.

From → de- + → orbit.

Of a spacecraft, the act or process of departing from an operational orbit. → de-orbit.

Noun form of → de-orbit.

A method for estimating the real orientation of a field and/or related velocities/separations from two-dimensional images.

→ de-; → projection.

To correct the intensity or flux of a spectral line by eliminating the → reddening effect of → interstellar dust.

De-redden, from → de- + redden verb of → red.

Vâsorxidan, from vâ-, → de-, + sorxidan verb of sorx, → red.

A magnitude which has been corrected for the interstellar reddening.

De-reddened, p.p. of → de-redden; → magnitude.

Borz, → magnitude; vâsorxidé p.p. of vâsorxidan, → de-redden.

The process that de-reddens. The state of being de-reddened.

Verbal noun of → de-redden.

A survey in which the observed objects are bighter than a given → apparent magnitude.

→ magnitude; → limited; → volume.

A → NASA infrared astronomical → space telescope launched in December 2009 to carry out an → all-sky survey from 3 to 22 → microns. With its 40-cm → telescope telescope and → infrared cameras, WISE aimed at a wide variety of studies ranging from the evolution of → protoplanetary disks to the history of → star formation in normal galaxies. In early October 2010, after completing its prime science mission, the spacecraft ran out of → coolant that keeps its instrumentation cold. However, two of its four infrared cameras remained operational. Hence, NASA extended the NEOWISE portion of the WISE mission by four months, with the primary purpose of hunting for more → asteroids and → comets, and to finish one complete scan of the main → asteroid belt. In August 2013, the WISE telescope's mission was extended for more three years to search for asteroids that could collide with Earth.

→ wide field; → infrared; → survey; → explorer.