A monumental 17th Century brass astrolabe from the former royal collection of Jaipur will be auctioned in London on 29 April. Described as perhaps the largest example of its kind, the hand-held astronomical instrument was once owned by Maharaja Sawai Man Singh II and later by Maharani Gayatri Devi before entering a private collection. It has never been publicly exhibited.

Crafted in Lahore by brothers Qa'im Muhammad and Muhammad Muqim, leading figures of the renowned Lahore School, the astrolabe reflects the scientific sophistication of the Mughal court. Weighing more than eight kilograms and richly detailed with star pointers, city coordinates and finely calibrated plates, it combines Persian and Sanskrit inscriptions, highlighting cross-cultural exchange. Experts say its precision and scale make it one of the most important surviving examples of early modern astronomical craftsmanship.

Expected to sell for between 1.5 million and 2.5 million pounds, the piece is likely to draw strong interest from museums and collectors. Its size, condition and royal provenance set it apart from other historic astrolabes previously offered at auction.