Hanle is hard to reach. It’s 10 hours or 270 km from the nearest city, Leh. It’s too cold at the best of times and home to 300-odd people. But to astrophysicists, it’s a stairway to heaven.The remote village houses the Indian Astronomical Observatory (IAO), which at 4,500 metres above sea level is one of the world’s highest, and affords some of the clearest views of the skies. Since June 12, it’s also been home to India’s first robotic telescope, a device with a 70-cm lens that networks with 17 others across the Northern Hemisphere to form GROWTH, a Global Relay of Observatories Watching Transients Happen. What happens when 18 telescopes combine forces? They form an exclusive, otherworldly club where it’s always night. Earth’s rotation means that any observatory will experience downtime – daylight obliterates the view of the beyond. But GROWTH’s connected telescopes, in the US, UK, Germany, Israel, India, Taiwan and Japan, let you still watch the same patch of sky from another part of the world; one where the sun hasn’t risen yet. WORKING FAST For astronomers tracking transient events (short-lived cosmic occurrences that can last mere hours or days), this is a bonanza. When a survey telescope detects the start of something interesting, all GROWTH telescopes respond, says GC Anupama, an astrophysicist with the Indian Institute of Astrophysics (IIAp), who heads the project. “Rapid and constant communication within the network ensures a quick follow-up by the facilities that are suitably located. It allows researchers to gather data in the first 24 hours of an event to understand, on a physics level, what’s happening and why.”Anupama operates the telescope from the IIAp centre near Bengaluru, 3,000 km away. A pre-programmed sequence of operations can remotely open the dome, aim the telescope towards the desired object, configure the instrument to observe what’s happening and record the relevant data. “An observer can eavesdrop periodically, from a remote location, via a regular Internet connection,” she says. GROWTH-IndiaHanle is so remote that a scientist needs to set aside at least five to seven days to spend a night or two here for observations. It is, however, largely cloud-free, with long nights and dark, pollution free skies – a delight for stargazers.The bots are especially helpful for sudden, urgent bursts of activity, says Varun Bhalerao a physicist at the Indian Institute of Technology-Bombay, and principal investigator in the project. “When LIGO [a large-scale American observatory] detects gravitational waves somewhere in the universe, it’s usually late at night for us and we’re sent scrambling,” he says. “Precious time is lost getting a telescope set up. A robotic telescope outsources the calibration to the machine, leaving the scientist free to do the analysis.”LOOKING AHEADIt will be a couple of months of fine-tuning before the bot takes over the Hanle telescope completely, leaving scientists to spend their time on interpreting readings. The global network aims to find electromagnetic counterparts to gravitational wave force – supporting proof of violent, energetic events in the universe. It could help understand how heavy elements combine to form a star and what happens when stars die. It also hopes to detect young starbursts and asteroids closer to Earth. So a system of small, linked telescopes is especially useful. “Think of the view from a moving train,” Bhalerao says. “Poles and closer objects appear to move by faster, trees in the distance are easier to observe. A large telescope is designed for long-range, precise focus. A small one covers a wider field. So instead of a sniper rifle, the smaller telescopes work like Rambo’s machine guns, covering a larger, closer area for longer.” The GROWTH-India telescope cost Rs 3.5 crore, funded by the Science and Engineering Research Board of India’s Department of Science and Technology. The network is led by the American institute Caltech and managed in India by the IIAp and IIT-B. At Hanle, IIAp engineer Angchuk Dorje has been keeping one eye on the telescopes and the other on the skies. It’s so remote, he says, that “a scientist needs to set aside at least five to seven days to spend a night or two here for observations”. It is however, largely cloud-free, with long nights and dark, pollution free skies – a delight for stargazers. “Whenever an astronomer or scientist visits, our faces glow at the latest astronomy news,” he says. The global interest in the new telescope marks an exciting phase, he adds.The IAO’s first telescope was set up 18 years ago, but a new one, the world’s largest at this altitude, will be ready next year. India is building a large telescope in Ladakh to study the sun. In 2016 in Nainital, ARIES, Asia’s largest optical telescope, was activated to study stars, magnetic fields and space debris. In South Africa, we’ve co-funded the largest single optical telescope in the southern hemisphere and are helping build the world’s largest radio telescope. And India is a partner to build the ambitious Thirty-Metre Telescope, aimed to be completed by 2030 and transform astronomy. “What India needs now are more human eyes trained towards the skies,” Bhalerao says. “We need at least 10 times more astronomers than we have.”
