Thiruvananthapuram (or Trivandrum) has a rich history in astronomy and is arguably one of the most important cities in the history of modern astronomical research in India. At the epicenter of this research has been the Astronomical Observatory which is now located in the University of Kerala. This was commissioned by the then Maharaja of Travancore, His Highness Swati Thirunal in 1836. This is a short write up about the pleasant surprise that awaited us when we visited this observatory, unannounced, one fine evening in October 2024.
Firstly, don’t confuse this with the other public telescope which is at the Priyadarsini Planetarium, a couple of kilometers away.
To be honest, we had very little expectation from our visit. We have visited many government outreach offices before, and the experience has, unfortunately, always been underwhelming. So, when we reached the gate of the Astronomical observatory, we were fully expecting to be shooed away, with contempt.
The security guard stopped us and enquired where we were heading to. I turned my palm into a circle of sorts and held it to my eye. He told we could proceed. This was very good sign. The road leading up the hill is not well lit, and a short 2-minute ride had us stop near a flight of stairs.
We went up the stairs and were greeted by Dr Jayakrishnan Ramakrishnan, Honorary Director of the Observatory. What followed was an interaction that could only be had with someone who is very passionate about astronomy. Dr Jayakrishnan is an Associate Professor at the department of Physics, University of Kerala.
Ridhi and I, introduced ourselves and explained what we do back in Bangalore. We also said that we had just come to check the place out, knowing well that the skies weren’t clear. Dr Jayakrishnan explained about the history of the place. They have a 14-inch telescope and an 8-inch telescope for public viewing. After exchanging pleasantries, we headed into the office located on the ground floor.
Dr Jayakrishnan is very enthusiastic about astronomy and if you are in Trivandrum, you must visit the place on any weekday between 6:30 PM to 8:30 PM. He has put in a lot of effort to display information related to the history of the place. This is unlike any other government outreach building. Not only do you feel welcome, but you also learn a lot of things from a knowledgeable physics professor, who is enthusiastic about public outreach.
(Note: There are photos and contact details here in the original post that you should copy manually).
We were led to a second room that had a huge Transit Telescope at its centre. This telescope is aligned the pole star through a window in the north side of the room. The telescope can move on one axis along the imaginary north pole – south pole line, also called as the meridian.
This telescope, also from the 19th century, has a bench, on which an observer would lie down and wait patiently for the target star to come into the center of the field of view of the telescope. This would signify that the target star had crossed the meridian or midway from its journey from rising in the east, to setting in the west. This is also known as a transit event for your local area. With a synchronized, reliable clock, an astronomer would record the exact time of the event. Now, you could use this as a base to log future meridian crossings and derive the exact time of the day with each passing. This observatory was also used to commission religious yearly almanacs (Panchangam) back in the day.
We also noticed that there were several antique eye pieces, a radiometer with a quartz dome to measure solar radiance. There were still many rolls of strip chart recorders stacked neatly in the room! These would have been used back in the day to record the electrical signals generated by the radiometers, making continuous recordings of solar irradiance through the day. I could not help but imagine a typical day in the life of an astronomer here about a century ago!
We also were able to see the personal 2 inch refractors of John Allan Broun, who was one of the early British astronomers who headed the observatory. One odd thing about the design was that the focuser moved the primary lens forward and backward, rather than move the eyepiece or diagonal.
They also have 3 sidereal clocks from 1841, and they still work!
(Video link referenced: https://www.youtube.com/watch?v=WWw4JY2dNXM)
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