Total Solar Eclipse Observation in Bangladesh: An Anushandhitshu Chorko Report July 22 2009

The 2009 total solar eclipse is over. We had waited and prepared for this event for six months, but now, with the excitement over, we cannot but feel a little empty. We look forward to another total eclipse, but the next total eclipse in the Bangladesh sky will not happen until 2114, one hundred and five years hence.  And for the people who will live during the 23rd century, not a single total eclipse is predicted for this region. But one should take heart in the fact that numerous partial eclipses will be seen during the rest of the 21st century–in fact, 37 partial eclipses are predicted for this region. The next total solar eclipse that will be observable from United States will be in 2017.

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Fig. 1: The 2009 July 22 Eclipse belonged to the Saros 137 cycle and its path covered a highly-populated section of the earth (source: NASA Eclipse Website).

To view a total eclipse, one needs to be in the lunar umbral shadow. This shadow circumscribes a narrow path on the face of the earth, only a few hundred kilometers in expanse. This makes only a tiny portion of the human population eligible for a totality. And even then, the shadow paths, more often than not, fall on oceans, making it impossible for most of humanity to enjoy this celestial phenomenon. Moreover, the lunar shadow races across the face of the earth with a speed in excess of 1500 km/hr, relegating the time of the totality to a meager few minutes.

The 2009 July 22 Eclipse belongs to the Saros 137 cycle (every eclipse belongs to a Saros cycle). Usually, the eclipses in the 137 cycle provide a longer totality time.  The 2009 eclipse was termed a monster not only because of its time, but also because it was to be witnessed potentially by hundreds of millions of people.

 

AC_Eclipse_P_13Fig 2:  To observe this monster, Shahjahan Mridha Benu, Ifteekhar Ayub, Prof. A.R. Khan and Dr. Dipen Bhattacharya traveled to Panchagarh two weeks before the eclipse to discuss the setup of an observation camp with the District Administration.

With respect to the observation, we had some specific goals in mind. We knew there was more than an 80% chance that the event would be washed out due to the inclement monsoon weather. Hence, as a backup we wanted to prepare a multimedia show that would provide a simulation of the eclipse even if the real eclipse was hidden behind the clouds. We used software called Skygazer and projected a real time image of the ongoing eclipse on a large screen so that the thousands of people could observe it.

AC_Eclipse_P_10Fig. 3: Surrounded by enthusiastic children, we prepare for the eclipse due next day morning.

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Fig. 4: The morning of the eclipse. We estimated almost 20,000 people gathered to experience the total eclipse.

We also had two special telescopes. One was a Coronado 40-mm personal solar telescope that had a built-in H-alpha filter, and the other was a Meade Schmidt-Cassaigrain 8-inch reflector equipped with a Baader neutral solar filter. A special CCD camera was attached to the Meade telescope so that we could project the image of the sun on the large screen. We wanted to take a series of pictures, including the progression of the totality, the coronal structure, the Baily’s beads and the Diamond Ring.

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Fig. 5: Preparing a display screen for the assembled spectators.

 Unfortunately, the clouds prevented us from tracking the sun with our telescopes and we had to rely on the simulation software to show the attendees what was happening in the sky.

filterFig 6About 8,000 filters were made out of 12-grade wielding glass.

But about half an hour after the first contact, nature cooperated and the eclipsed sun peeked through the cloud. The crowd welcomed the appearance with thunderous applause. It was wonderful to see people truly appreciating this spectacle of nature.

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Fig. 6:
The partially eclipsed sun.

The clouds prevented us from seeing the lunar umbra approaching, but it announced its arrival by suddenly plunging everything into an eerie darkness. A hush fell on the stadium only to be broken by continuous thunderous clapping. One had to be there to feel this emotion as lights from thousands of mobile phones shone like fireflies.

AC_Eclipse_P_4Fig. 7: A total darkness enveloped the area during the four minutes of the total eclipse.

The bright planet Venus appeared at the zenith. Mercury appeared beneath the sun and the bright star Sirius shone at an angle. Minutes passed, and suddenly the clouds parted, showing a fully eclipsed sun. It was truly a remarkable sight and I was overwhelmed with emotion. A bright diamond appeared at the upper-right corner of the sun and within a fraction of a second the sky lighted up as if a celestial switch had been turned on to light up the Sun. And only then I realized the true difference between a total and a partial eclipse. The total eclipse plunges the earth into a strange darkness, with even a sliver of the Sun behaving like a luminous object capable of filling the sky with bright light.

Anushandhitshu Chokro’s Naimul Islam (Opu) made an ingenuous contraption that could hold five cameras on an equatorial mount and easily track the Sun. Such a device is truly unique in Bangladesh. Even though the clouds prevented him from tracking the Sun, he managed to take about 900 frames through his 300-mm Tokina lens.

AC_Eclipse_P_3Fig. 8: The press was very much interested in the eclipse.

Traveling with us was Colin Henshaw, a fellow of the Royal British Astronomical Society. He had an 80-mm refractor equipped with a Canon 30D camera. His goal was to capture the earthshine on the moon during the total eclipse. Earthshine is the reflected sunlight from the earth that falls on the lunar surface. It is amazing to contemplate that even during a total eclipse, the chromospheric glow of the Sun could reflect off the Earth.

One of our successes in this eclipse campaign was that we managed to convince people that it was not a good idea to look at the sun through exposed ordinary or X-ray film or CD disks. We spent considerable time tracking down certified solar glasses that would be safe for eclipse viewing. Certified shades were imported from abroad, from which thousands of welding shield glasses of Grade 12 were prepared.

Even with Grade 12, we advised people not to look at the Sun for more than ten seconds at a time. We also encouraged people to look at the sun through other indirect methods. I am happy to report that we obtained considerable success in this regard. I have seen numerous post-eclipse photos from other countries where even children were using ordinary camera film as solar shield–an absolutely unacceptable method.

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Fig. 9: Anushandhitshu Chokro Science Organization’s Naimul Islam Opu prepared this composite image of the eclipse progression from different exposures.

We do have some personal regrets about not getting a perfect shot through the Coronado Solar Telescope because so many people clamoured to get a glimpse of the reddened (due to the H-alpha filter) eclipsed Sun. But in the end, we are satisfied that many got to peek through that telescope to get a personal experience of seeing the sun up-close. With the other thousands of people gathered in the stadium, we were linked to human history through the thrilling shared experience of a grand cosmic drama. We are very glad for that.

AC_eclipse_P_1Fig. 10: The members of Anushandhitshu Chokro Science Organization celebrates a successful eclipse observation.