However, his talents in astronomy were noticed by Jérôme Lalande, for whom he became a friend and proof-reader of the second edition of his book "L'Astronomie".

In the same year, he also produced his first astronomical work, a paper on an occultation of Aldebaran by the Moon, and presented it as a memoir to the Academy of Sciences.

He was arrested after it was suspected his instruments were weapons, he was interned in Barcelona after war broke out between France and Spain, and his property in Paris was confiscated during The Terror.

A particularly intriguing fact about this project was that Méchain was uncertain of the precision of his measurements owing to anomalous results in verifying his latitude by astronomical observation.

It represents in each meter an error of approximately 0.23 millimetres[3] – slightly more than the width of a single strand of human hair.

This took him back to Spain in 1804, where he caught yellow fever and died in Castellón de la Plana.

On 24 June 2002, Asteroid 21785 Méchain was named in his honour, discovered by Miloš Tichý at Kleť Observatory on 21 September 1999, and provisionally designated 1999 SS2.