The Regional Meteorological Centre on College Road, Nungambakkam, which issues Chennai’s rain and cyclone warnings, sits on the site of the Madras Observatory, one of the first modern scientific observatories in Asia. Its story begins on 5 December 1786, when William Petrie, an East India Company officer, recorded his first observation at a private observatory in Egmore. The Company took it over in 1789, and in 1792 it moved into a new building at Nungambakkam.
From that compound came the longitude that anchored the Great Trigonometrical Survey of India, the Madras time used by the railways, star catalogues still cited by astronomers, and weather records that go back to the 1790s. Here is what happened there and what survives.
Petrie’s telescopes to a Company observatory
Petrie started with two three-inch telescopes, two astronomical clocks and a transit instrument, the Indian Institute of Astrophysics records. The IIA, now based in Bengaluru, counts the Madras Observatory as its own beginning. When Petrie left, he handed his equipment to the Company. Michael Topping, the Company’s marine surveyor, became director in 1789 and designed the new Nungambakkam building, completed in 1792 under Governor Sir Charles Oakeley, according to R. Kochhar’s history of the observatory.
A granite pillar from that period still stands inside the Regional Meteorological Centre. Known as the Topping pillar, it carries inscriptions in Tamil, Telugu, Urdu and English, with the Tamil text giving the year 1792 and the Kali Yuga year 4893, reports The South First.
Longitude, Madras time and the Great Survey
John Goldingham, who led the observatory in two spells between 1796 and 1830, fixed its longitude at 80 degrees 18 minutes 30 seconds east in 1802, using eclipses of Jupiter’s moons. On 10 April 1802 William Lambton began measuring a baseline at Madras for what became the Great Trigonometrical Survey of India. Goldingham’s figure gave Madras its own local time, about five hours and 21 minutes ahead of Greenwich, DT Next notes, and a gun fired from Fort St George at 8 pm each night let ships and households set their clocks.
When the railways spread after 1856 they adopted Madras time to keep timetables consistent across the Presidency and much of India. It stayed in railway use until Indian Standard Time, set at 82.5 degrees east, was introduced in 1906.
Weather records since the 1790s
Goldingham began regular meteorological readings in 1793, and his barometric register ran from 1796 to 1825 with a gap. IMD’s own account of its evolution marks 1793 and the Madras observatory as the start of instrumental meteorology in India, decades before the department itself was founded in 1875. Thomas Glanville Taylor, director from 1830, extended observations to the Nilgiris, running a high-altitude station at Dodabetta from 1847.
Asteroids, variable stars and an eclipse
The observatory’s most productive astronomer was Norman Pogson, director from 1861 to 1891. Using an eight-inch telescope he discovered five asteroids and several variable stars, Kochhar notes. Pogson is better known worldwide for the logarithmic star magnitude scale still used today. The IIA history adds other firsts:
- In 1867 C. Raghunathachary found the brightness variation of the star R Reticuli, perhaps the first astronomical discovery by an Indian in modern times.
- During the total solar eclipse of 18 August 1868, Pogson’s observations at Masulipatam recorded a yellow line later linked to helium.
- Taylor’s catalogue gave positions for more than 11,000 stars.
The move to Kodaikanal
Madras was hot, humid and increasingly bright at night. On 20 July 1893 an Indian Observatories Committee decided to set up a solar physics observatory at Kodaikanal. Astronomical work shifted there by 1899, with first observations at Kodaikanal in 1901, while Madras kept meteorology and the time service. Kodaikanal’s observatory later became part of the IIA, formed as an autonomous institute in 1971.
Nungambakkam became one of IMD’s regional centres. In 2025-26 it marked 150 years of IMD and 80 years of the Chennai regional centre with events listed on the RMC Chennai website.
Can you visit?
The Regional Meteorological Centre is a working government office, and the Topping pillar is inside its compound, so there is no general public access. Groups such as schools sometimes visit by prior arrangement; contact RMC Chennai through its website. IMD’s open days, when held, are announced there too.
Quick answers
When was the Madras Observatory founded?
William Petrie began observations in Egmore in 1786. The Company’s observatory at Nungambakkam was completed in 1792.
Where is the Madras Observatory now?
Its site is the Regional Meteorological Centre, College Road, Nungambakkam. Astronomy moved to Kodaikanal around 1899.
What was Madras time?
Local time based on the observatory’s longitude, about five hours 21 minutes ahead of Greenwich, used by railways until IST in 1906.
Is the pillar open to the public?
No regular access. It stands inside the IMD compound.
Information checked against official sources on 18 October 2026. Fees, dates and rules can change; confirm on the linked official pages before acting.
Sources
- A brief history of IIA (Indian Institute of Astrophysics)
- Evolution of IMD (India Meteorological Department)
- IMD150 – RMC80 (Regional Meteorological Centre, Chennai, IMD)
- Madras Observatory: the beginning of modern Indian astronomy, R. Kochhar (Journal of Astronomical History and Heritage, 2011)
- Those were the days: Meet John Goldingham, the polymath of Madras (DT Next)
- Chronicles of Madras Standard Time and its lasting temporal legacy (The South First)
