The Indian Institute of Astrophysics (IIA), an autonomous body under the Department of Science and Technology, has played a key role in the Surya Tilak project in Ayodhya. Under the Surya Tilak Project, on the occasion of Shri Ram Navami in the month of Chaitra, sunlight was shone on the head of Shri Ram Lala at 12 noon today. The Indian Institute of Astrophysics (IIA) team calculated the Sun's position, designed and optimized the optical system, and performed integration and alignment at the site.
The English calendar date of Shri Ram Navami festival changes every year according to the lunar calendar. Therefore, every year on the day of Shri Ram Navami the position of the Sun in the sky changes. Detailed calculations show that the English calendar date of Shri Ram Navami repeats every 19 years. Calculating the position of the Sun in the sky these days requires expertise in astronomy. The IIA team led the calculations to identify the calendar days of Shri Ram Navami for a cycle of 19 years. Thereafter its recurrence, location in the sky on the calendar dates of Ram Navami is estimated.
The IIA team has carefully considered the size and structure of the mirror and lens, the idol, the lens and the mirror holder in the entire system to allow the sun's rays to reach the upper part of the forehead of the idol from the top of the temple and provide adequate illumination on the idol for about 6 minutes. The opto-mechanical design of the assembly as well as the manual mechanism for changing the position of the first mirror according to the position of the Sun in the sky also led to the design of an opto-mechanical system. Significant design optimizations as well as simulations were performed to reach various degrees of certainty in the functioning of the system.
The opto-mechanical system in the Surya Tilak project in Ayodhya has been executed by CBRI. The instrument is manufactured by Optica, Bangalore.