A New Mystery Deduced

I came across a mystery post today, while browsing across my Google+ Stream. And you now, the caption really interested me: “Not really sure from where this came from.” It’s one of the few answers I can brag to deduce wonderfully.
So, before I set off with all my (what people call) endless jabber, let me show you what I saw.

An animated GIF showing day and night on Earth. What set alarms bells ringing was the position of India in this image.

The Alarm Bells Are Ringing

What particularly intrigued me was the position of India on the image. Why the hell would any space agency place geostationary satellites atop another country, unless they have military objectives. I know this is not such a satellite, since data from such satellite are not revealed in public.

So that means that this satellite has been launched by a country in the dominating region of the field of view. And the only country which can do that is India.

But this seemed like a pretty simple time-lapse.

It is conspicuous that the satellite is geostationary, because it is inherently noticeable that the satellite remains at the same position. Geostationary Satellites have an orbit whose inclination is 0 (orbital inclination with reference to the Earth’s Equator). So, this satellite is effectively seated on the Earth’s Equator.

Also, the Equator is at the centre of the image.

Here’s an excellent blog to understanding geostationary satellites and its orbits:

If you look more closely, you’ll see that approximately the centre of India is the centre of the image. If you recall (in Geography),

The meridian of longitude which approximately divides a country into two equal halves is known as the Standard Meridian. 
In the case of India, the Standard Meridian is 82o 30′ E, which passes through the city Allahabad. 

So, here’s what we have deduced so far:

  1. The Equator of the Earth lies at the centre of the images. Therefore, the satellite is in geostationary orbit.
  2. The approximate location of the Standard Meridian of India is also at the centre of the image.

So that would imply that, the satellite is positioned approximately on the 82o E meridian of longitude. And it’s in geostationary orbit. 

My next step was to figure out exactly what satellite that was. I was well aware that the specialized imaging satellites of the Indian Space Research Organisation (ISRO) were not in geostationary orbit. I even checked whether they are.

Specialized imaging and remote-sensing satellite, therefore, are out of my list of suspects.

Next comes along the list of geostationary satellites. My primary suspects were the INSAT group of satellites. After looking through mission parametres of all of them, I had shortlisted two satellites.

  1. INSAT 2E: Positioned on the 83o E meridian of longitude.
  2. INSAT 3D: Positioned on the 82o E meridian of longitude. 

Now that all the suspects had been shortlisted, my next step was to identify whether any of these satellites had imaging capabilities. 

It turned out, they did. Both of them, were also deputed weather analysis as one of their objective.

So now, I am in a fix. These images were taken from which satellite? INSAT 2E, or the more recently-launched INSAT 3D? The chances are 50-50.

My Unconfirmed Deduction

What I have spoken so far is based on solid, ground (official) facts. However, I cannot speak any further, because I lack proof. I need some more evidence, which I cannot find, to say whether the source satellite was INSAT 2E or INSAT 3D.


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