An autonomous organization under the Department of Science and Technology (DST), the Indian Institute of Astrophysics (IIA), Bengaluru, has been instrumental in the "Surya Tilak" project in Ayodhya, wherein on April 17, at 12 p.m., on the occasion of Ram Navami, sunlight was shone onto the forehead of the Ram Lalla idol. Every year, this ceremony will be repeated.

The DST secretary, Abhay Karandikar, wrote on X: "The team under the direction of IIA accomplished the integration and alignment at the site, constructed and optimized the optical system, and calculated the Sun's location. Since the temple is still under construction, IIA specialists did image optimization and altered the design to fit the current structure. This design was created for the Surya Tilak and had four mirrors and two lenses.

After the entire temple is built, the four mirrors and four lenses that make up the Surya Tilak's final design will be put into place by fixing the mirrors and lenses permanently.

We've used a scientific design based on periscope principles, and the system has to fit into the structure in a precise spot based on the temple architecture, IIA director Annapurni Subramaniam told TOI. The project was initiated around three years prior. After the concept was finalized, we had to put it into practice before publishing. Following this, the IIA provided technical advice, on the basis of which Optica, Bengaluru, produced the apparatus and Central Building Research Institute (CBRI) executed the opto-mechanical system installation at the location.

Because it is based on the Lunar Calendar, the Ram Navami festival's date in English varies annually. Karandikar so said that on the day of Ram Navami each year, the Sun's position in the sky changes.

Extensive computations reveal that the date of Ram Navami in the English calendar occurs once every 19 years. These days, astronomical knowledge is necessary to determine the Sun's location in the sky. Karandikar continued, "The IIA team oversaw the assessment of the size, shape, and placement of mirrors and lenses in the system to allow enough light to fall on the idol for around six minutes.

According to Karandikar, the lens and mirror holder assembly's optomechanical design as well as a manual mechanism were used to adjust the first mirror's position in relation to the Sun's position in the sky. This allowed the entire system to function flawlessly and ensured the success of the Surya Tilak.