India.Ladakh · ITBP/Army UAP

Between 1 August and 15 October 2012, an Indo-Tibetan Border Police (ITBP) unit posted at Thakung, near Pangong Tso lake in Ladakh (a strip of extreme altitude along the contested border with China) logged more than a hundred sightings of what the reports called 'Unidentified Luminous Objects' (ULO): yellowish spheres that glowed "at day and by night", according to the coverage of the time.

The pattern described by the observers was recurrent. According to IBTimes' report of 7 November 2012, which summarized India Today's story, the spheres appeared to rise from the horizon on the Chinese side and move slowly across the sky for three to four hours before disappearing (three to five according to The Times of India, as quoted by HuffPost). ITBP personnel sent reports to their Delhi headquarters, according to HuffPost's roundup of 9 November 2012; the Deccan Herald dated the ITBP's letter to the government to October and added that the force also alerted the Army's 14 Corps in Leh, which reported to Northern Command in Udhampur.

In September the Indian Army deployed a mobile ground-radar unit and a spectrum analyzer to a mountaintop near the lake. Neither picked up any signal, and the press of the time read this as a sign the objects were not metallic; according to the Deccan Herald, the Air Force's radars detected nothing either. The Army also sent a drone toward one of the objects, but lost sight of it. Military officials who studied the hazy photographs taken by the ITBP ruled out drones, UAVs and low-orbit satellites, but neither the Army nor ISRO, DRDO or NTRO managed to identify the lights. In September, astronomers from the Indian Astronomical Observatory at Hanle, some 150 km away, observed the objects for several days and, according to HuffPost, summarizing India Today, ruled out meteors and planets without managing to identify them; according to Army officials quoted by IBTimes, the only assessment they reached was that they were "non celestial" in nature. In December 2012, official sources quoted by the Deccan Herald spoke of a preliminary report pointing to Chinese lanterns and of a request to ISRO to send scientists to confirm it; the government turned down a proposal to shoot one of the objects down. On 26 November 2012, answering a Lok Sabha question about the 14 Corps reports, Defence Minister A. K. Antony replied in writing that there was "no conclusive proof" of UFOs over the Indo-China border.

The identification that closed the case came in 2013. According to Calcutta's The Telegraph (24 July 2013), as picked up by The Register and UAS Vision, the Army called in two astronomers from the Indian Institute of Astrophysics in Bangalore, among them Tushar Prabhu, to determine whether the objects were celestial or terrestrial. Between August 2012 and February 2013 the Army had logged 329 sightings at Thakung, 155 of them as violations of the Line of Actual Control. According to the same coverage, the astronomers were told that the first object, seen from a post at about 4,715 m near Thakung, appeared on the horizon around 6 pm and stayed visible until about 5 am, and that the second appeared around 4 am and faded around 11 am; a regular observer at the post had noticed a four-minute shift in the appearance of one of them from one day to the next. At the Army's request, the two astronomers told military personnel how to measure the lights' position with a theodolite (horizontal angle and elevation), measurements taken from 17 to 22 February 2013 at Point 4715, and on analysing them concluded that the object observed from there was Jupiter (the measurements matched the planet's diurnal motion) and the morning one, Venus. From that altitude both planets look brighter than usual, and a body rising in the east can seem to be crossing the control line toward the Indian side.

An ephemeris calculation for Thakung (33.8° N, 78.8° E) supports the identification and sets its limits. Jupiter rose in the east-northeast (azimuth about 63°, on the side where Pangong runs into Tibet) at magnitude −2.0 to −2.7, about four minutes earlier each day: around 1 am in early August, around 8:30 pm in mid-October and at dusk from late November. Venus, at magnitude close to −4, rose between 2 and 5 am throughout the period. The 6 pm to 5 am window described to the astronomers matches Jupiter in November and December. The identification rests on measurements from February 2013; for August–October 2012, Venus (rising around 2–3 am in the east-northeast, magnitude −4.3 to −3.9, visible after dawn) fits the description, although nobody measured it. The original ITBP report was never published in full, and what is known of it comes from the Indian press of the time.

Here a border force's report documentably reached the political level (ITBP, Delhi headquarters, 14 Corps and Northern Command, a parliamentary question answered by the Defence Minister), and the Army deployed dedicated instrumentation, radar and a spectrum analyzer, to characterize it. It illustrates how a modern state processes a mass sighting in a zone of maximum geopolitical sensitivity, and also how it gets it wrong: for months Chinese drones, a psychological operation and lanterns were floated, and shooting one down was even proposed, before astronomers were asked to measure the lights against the stars.

The Indian Institute of Astrophysics' identification of Jupiter and Venus rested on theodolite measurements the Army took on their instructions, and fits the main features of the sighting: nightly persistence of hours, great brightness, rising in the east, absence of radar echo and absence of emission. Two loose ends remain that the public record does not tie up: in September 2012 the Hanle astronomers observed the objects for several days and ruled out meteors and planets, and the identification rests on measurements from February 2013; for August–October 2012, Venus fits the description, although nobody measured it. Neither weighs enough against a direct measurement, but they prevent treating the identification as settled for each of the hundreds of sightings. The solidity of that chain and the triviality of the physical cause are not contradictory.