PRESS INFORMATION BUREAU (DEFENCE WING)

GOVERNMENT OF INDIA

IAF ROLE IN STUDY OF SOLAR ECLIPSE SUSTAINS SINCE 1995

New Delhi: July 21, 2009

 Tail-chasing an enemy jet and shooting it down from the sky remains the ultimate dream of every fighter pilot. Seldom do pilots in such aerial chases go beyond the supersonic regime, let alone beyond that.

Now imagine chasing a target at Mach 2.5, more than twice the speed of sound and yet not manage to catch up, a chase that can only be fathomed out of a scene from a star trek kind of sci-fi film. Incredible it may sound but it is just what IAF pilots did when chasing the umbra shadow during the total solar eclipse on October 24, 1995. It also heralded IAF’s participation in scientific study of total solar eclipse that continues till date.

After the total solar eclipse of 1898 over India, the next occurrence took place only in 1980. Not until the subsequent total solar eclipse in 1995, did the IAF assist the Department of Science and Technology (DST) in their quest to film this celestial alignment. With aviation speeds streaking past the supersonic barrier, the scientific experiment of photographing the images from the air was now made possible.

Air Marshal S Mukerji, Air Officer-in-charge Personnel (AOP) at Air Headquarters was the then Commanding Officer of IAF’s only Mig-25 Squadron, christened  – Trisonics, based at Bareilly. Then a Group Captain, Air Marshal Mukerji had this rare opportunity to fly the Mig-25 on that day to film the Sun’s corona from an astounding altitude of 80,000 feet, straight from the Stratosphere.

“We flew at Mach 2.5 in the path of the eclipse at 80,000 feet along the planned central axis of the eclipse over Neemkathana, near Agra”, recalls Air Marshal Mukerji of his historic sortie that finds a mention in his flying log book plainly as - ‘Supersonic Profile’. Weather and other visibility were not any constraints, he says, as clarity at stratospheric levels is far better than that nearer ground.

With a manual Hasselblad camera mounted above the instrument panel, a special lead and button provided to the second pilot, Wing Commander YS Babu seated in the front cockpit, the duo with special solar filters on their visors flew straight towards the Sun for a minute and twenty-four seconds, clicking never-before images of the spectacle, during the total solar eclipse. 

“A lot of preparation went in ahead of the sortie. The sortie route had to be charted, axis programmed on the inertial navigation system and briefings by scientists with NASA charts were done. The aircraft were put on jacks, the angle-of-attack or ‘alpha’ simulated on ground to harmonize the camera along the axis. In addition, the aircraft belly camera could capture the shadow beneath that was 85 kms in width”, recounts Air Marshal Mukerji of the preparations.

Despite a top speed of Mach 3.2, it was not quick enough to catch-up with the umbra shadow that notched Mach 5, on that occasion. “This time around a high speed chase would not be necessary as the speed of the Umbra shadow over Gulf of Khambhat begins with Mach 50-60 slowing down to Mach 20 near Bhopal”, says Dr. Vinay B Kamble, Director, Vigyan Prasar and Adviser, DST who is coordinating with the IAF to capture the longest total solar eclipse of the 21^st century.

“This year’s eclipse is significant for its long duration as also that the next eclipse will be in 2034, over Kashmir valley for a short duration over India. The total solar eclipse after that will only be in 2114’, disclosed Dr. Kamble, after a trial sortie undertaken today at Agra. Among other senior Scientists involved in the experiment with the IAF include Prof. P Venkatakrishnan, Dr. Shibu Matthews from Udaipur Solar Observatory; Prof K.E. Rangarajan and Dr. B. Ravindra from Indian Institute of Astrophysics, Bangalore.

The 10-member team of scientists and camera team from Doordarshan will be flying in an AN-32 from Agra airbase in an endeavour to capture and film the eclipse tomorrow. The aircraft will fly along the central axis on a north-westerly direction at an approximate altitude of 25,000 feet reciprocal from overhead Khajuraho and land back at Agra. Meanwhile, a Mirage-2000 trainer will also take off from Gwalior airbase and the pilot from the rear seat will click images even as the fighter flies in an angular track to the central axis.

The Eclipse begins tomorrow at 5:28 am IST when the shadow of the moon touches the Earth at local sunrise at a point in the Arabian Sea close to the western coast of India. The eclipse ends at l0:42 am IST when Moon's shadow finally leaves the Earth at local sunset at a point in the South Pacific Ocean. At approximately 6:23 am IST, the umbra of the eclipse will touch the earth at sunrise at a point in the Gulf of Khambhat in the Arabian Sea near the southern coast of Gujarat. At this time, the path of totality will be about 200 Km wide and the duration of totality at the central line will be about 3 minute 30 seconds.

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TK Singha from Agra/MKR-