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

1) The act of obscuring.
2) The state of being obscured.

→ obscure; → -tion.

1a) Lacking in light or illumination; dark; dim; murky.
1b) Indistinct to the sight or any other sense.
1c) Not clear to the understanding.
2) To make dark, dim, indistinct, etc.

From O.Fr. obscur "dark, dim, not clear," from L. obscurus "covered over, dark, obscure," from ob "over" + -scurus "covered," from PIE *(s)keu- "to cover, conceal;" from which derives also the term → sky.

Tiré, from Mid.Pers. târag "dark, turbid," related to târik "dark," Mid.Pers. târig "dark," târ "darkness," Av. taθra- "darkness," taθrya- "dark," cf. Skt. támisrâ- "darkness, dark night," L. tenebrae "darkness," Hittite taš(u)uant- "blind," O.H.G. demar "twilight."
Tiré kardan compound verb with kardan "to do," → -ize.

A structure of dust and gas postulated to surround the central → black hole in an → active galactic nucleus (AGN). The presence of an obscuring torus allows the unification of the two main types of AGNs containing a → broad-line region (Type I) and a → narrow-line region (Type II), respectively. In this unified model, the two types represent the same sort of object, the appearance of which depends on the viewer's → line of sight. The best evidence for this model comes from spectropolarimetry observations of some type II AGNs in which broad → emission lines are seen in → polarized light, as would happen if the broad-line region truly were hidden, and the light were being reflected off the torus and into the viewer's line of sight.

→ obscure; → torus.

The state or quality of being obscure.

→ obscure + → -ity.

1) General: The character of something that can be observed.
2) Astro.: The possibility that an object be observable at a particular time.
3) Control theory: A measure for how well internal states of a system can be inferred by knowledge of its external outputs.

From → observable + → -ity.

1) Capable of being or liable to be observed.
2) A quantity that can be measured.
3) Quantum mechanics: A → real dynamical variable whose → eigenstates form a → complete set.

From → observe + → -able.

The extent of the Universe that we can see with the aid of the largest telescopes. Its ultimate boundary is determined by the → cosmic horizon size.

→ observable; → universe.

1) An act or instance of following a custom, rule, or law.
2) A customary practice, rite, or ceremony; a rule governing members of a religious order.
3) An act or instance of watching (Merriam-Webster.com).

→ observe; → -ance.

Nepâhdâri, on the model of negâhdâri "preservation, protection," from nepâhdâr, → observant, + -i.

1) Paying strict attention.
2) Careful in observing (Merriam-Webster.com).

→ observe + -ant, a suffix forming adjective, → -ance.

Nepâhdâr, from nepâh present stem of nepâhidan, → observe, + dâr preset stem and agent noun of dâštan, dâridan "to have, hold, maintain, possess," → protected band.

1) Act or instance of observing; → observe.
2) Careful watching of an astronomical object or event using appropriate instruments, usually for collecting data.

Verbal noun of → observe.

Pertaining to, or founded on observation, especially based on observation rather than theory.

Adj. of → observation.

That part of astrophysics that is mainly concerned with the collection of observational data, in comparison with theoretical astrophysics

→ observational; → astrophysics.

An error in observation arising from systematically favoring brighter or weaker objects or some particular object morphologies; e.g. → Malmquist bias.

→ observational; → bias.

The application of observational data to the study of the Universe as a whole.

→ observational; → cosmology.

A feature appearing in an observation, which is not intrinsic to the object observed, but is due to the inappropriate method used (e.g. limited angular resolution).

→ observational; → effect.

The difference between a measured value of quantity and its true value.

→ observational; → error.

A place or building equipped for making observations of astronomical, meteorological, or other natural phenomena, especially a place provided with a telescope for observing astronomical objects.

From Fr. observatoire, from L. observa(re), → observe, + -toire, from L. -torius, from -tor a suffix forming agent nouns + -ius adj. suffix.

Nepâhešgâh, from nepâheš, → observation, + -gâh suffix of place (O.Pers. gāθu-, Av. gātav-, gātu- "place, throne, spot" (Skt. gátu- "going, motion; free space for moving; place of abode," PIE *gwem- "to go, come").

To watch carefully or note for a scientific or special purpose, e.g. to observe a star (astronomy), to observe the behavior of a patient (medicine, psychology), an animal (ethology, zoology), social groups (sociology), etc.

From O.Fr. observer, from L. observare "watch over, look to, attend to, guard," from ob "over" + servare "to watch, keep safe," from PIE base *ser- "to protect;" cf. Av. har- "to guard, observe, pay attention to," haraiti "guards, keeps," harətar- "protector, watcher," harəθra- "guarding, protection," hāra- "watched, guarded," Mod.Pers. zinhâr "beware!, mind!," Gk. heros "protector, hero."

Note 1: Observation is the most important basis of empirical sciences. All theories rely on observation, and must finally be supported by observational evidence. Persian, in contrast to European languages, lacks a distinct term that recognizes observation as a conceptual premise of sciences. In astronomy the Ar. rasad (رصد) is currently used, while in classical astronomical texts the Pers. pâyidan (پاییدن) is used mainly by prominent figures like Biruni and Tusi. However, the term rasad is never used for cases outside astronomy. The situation for other sciences is not clear. Often one resorts to the Ar. loanword mošâhedé "to look at each other," which lacks ability to form derivatives. Therefore, here we suggest a term that can be used in all fields of knowledge.

Nepâhian, from ne- + pâhidan. The prefix ne- "down; into" (as in negâh "look, glance," negaristan "to view, look at," nešastan "to sit down," nemudan "to display") from O.Pers./Av. ni- "down, into;" cf. Skt. ni "down," nitaram "downward," Gk. neiothen "from below," cf. E. nether, O.E. niþera, neoþera "down, downward, below, beneath," from P.Gmc. *nitheraz, Du. neder, Ger. nieder; PIE *ni- "down, below."
The second component pâhidan, variants pâyidan, pâsidan "to watch, observe, look steadily;" Mid.Pers. pây- "to protect, guard;" Sogdian p'y "to observe, protect, watch over;" O.Pers. pā- "to protect," pāta- "protected;" Av. pā- "to protect," pāti "guards," nipā(y)- (with ni-) "to watch, observe, guard," nipātar- "protector, watcher," nipāθri- "protectress;" cf. Skt. pā- "to protect, keep," tanû.pā- "protecting the body," paś.pā- "shepherd;" Gk. poma "lid, cover," poimen "shepherd;" L. pascere "to put out to graze," pastor "shepherd;" Lith. piemuo "shepherd;" PIE base *pā- "to protect, feed."

Note 2: Since pây-, pâyidan is used for → conserve, we adopt the variant pâh-, pâhidan, which is extant in Lâri and Gerâši dialects; cf. Gilaki pâstan, pâssan "to guard, pay attention." In fact the interchange of phonemes h, i and s is not rare in Indo-European languages.

Note 3: Examples of pâyidan "to observe" in astronomy, from Biruni's al-Tafhim (written c. 1029 A.D.)
p. 313: و بپای ارتفاع آ فتاب را.
p. 64: و بپای تا بدایره اندر آید.

Note 4: As indicated above, nepâh- exists in Av. as nipāy- "to watch, protect."

Pertaining to a value which has been measured, in contrast to one which is computed.

Past participle of → observe.

1) Someone or something that observes.
2) Idealized person or piece of equipment, often hypothetical, that measures relevant properties of a physical system.

Agent noun, from → observe + → -or.