Question: Which techniques were use to originally make astronomical observations?
About the article "Gravitational wave", section "Astrophysics and gravitational waves".

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Symbols for aspects and nodes appear in medieval texts, although medieval and modern usage of the node symbols differ; ☊ formerly stood for the descending node, and ☋ for the ascending node.
In describing the Keplerian elements of an orbit, ☊ is sometimes used to denote the ecliptic longitude of the ascending node, although it is more common to use Ω (capital omega), which was originally a typographical substitute for the old symbol.
The symbols for aspects first appear in Byzantine codices.
Of the symbols for the five Ptolemaic aspects, only the three displayed here—for conjunction, opposition, and quadrature—are used in astronomy.
Symbols for a comet (☄) and a star () have been used in published astronomical observations of comets.
In tables of these observations, ☄ stood for the comet being discussed and for the star of comparison relative to which measurements of the comet's position were made. 
Paṇḍita Jagannātha Samrāṭ (1652–1744) was an Indian astronomer and mathematician who served in the court of Jai Singh II of Amber, and was also his guru.
Jagannātha, whose father's name was Gaṇeśa, and grandfather's Viṭṭhala was from a Vedic family originally from Maharashtra.
As suggested by Jai Singh, he learned Arabic and Persian, in order to study Islamic astronomy.
Having become proficient in these languages, he translated texts in these languages into Sanskrit.
These translations include:  "Rekhā-gaṇita", a translation of Euclid's "Elements" made from Nasir al-Din al-Tusi's Arabic recension of the same.
For this work, he had to coin more than a hundred Sanskrit mathematical terms  "Siddhānta-sāra-kaustubha", a translation of Ptolemy's "Almagest" from Nasir al-Din al-Tusi's Arabic version His original works include: ‍ "Siddhānta-samrāṭ", which describes astronomical instruments, their design and construction, and observations.
It also describes the use of these observations in correcting parameters and preparing almanacs.
It mentions how J‌ai Singh, who earlier used astronomical instruments (such as the astrolabe) made of metal, later switched to huge outdoor observatories (such as the Jantar Mantar), as they were more precise; also they were made of stone and mortar rather than brick, to diminish the effects of wear-and-tear and climate.
"Yantra-prakāra", which describes astronomical instruments, measurements, computations, etc.
in more detail, and also observations made by him.
Jagannātha held that when theory and observation differed, observation was the true "pramāṇa" and overruled theory.
While he used and described a number of astronomical instruments, telescopes were not one of them. 
Transit observations in 1874 and 1882 allowed this value to be refined further.
Several expeditions were sent to the Kerguelen Archipelago for the 1874 observations.
The American astronomer Simon Newcomb combined the data from the last four transits, and he arrived at a value of about 149.59 million kilometers (±0.31 million kilometers).
Modern techniques, such as the use of radio telemetry from space probes, and of radar measurements of the distances to planets and asteroids in the Solar System, have allowed a reasonably accurate value for the astronomical unit (AU) to be calculated to a precision of about ±30 meters.
As a result, the need for parallax calculations has been superseded. 
The Orbiting Astronomical Observatory (OAO) satellites were a series of four American space observatories launched by NASA between 1966 and 1972, which provided the first high-quality observations of many objects in ultraviolet light.
Although two OAO missions were failures, the success of the other two increased awareness within the astronomical community of the benefits of space-based observations, and led to the instigation of the Hubble Space Telescope. 
The 9C survey at 15 GHz (9C) is an astronomical catalogue generated from the radio observations of the Ninth Cambridge survey at 15 GHz.
It was published in 2003 by the Cavendish Astrophysics Group of the University of Cambridge.
The catalogue was originally made in order to locate radio sources which were interfering with observations using the Very Small Array, but the catalogue has also proved useful for other astronomical programs.
Sources are labelled 9CJHHMM+DDMM where "HHMM+DDMM" are the coordinates in the J2000 system, e.g.
9CJ1510+4138.