Amateur Astronomers across the world have made a significant contribution to the science of astronomy by measuring stellar light.
There are three main observational fields in which amateurs can make a valuable contribution:
- Variable stars: The stars whose brightness or rather magnitude changes with time;
- Occultations: When a star is blocked by the Moon or an asteroid or even moons of Jupiter which play hide and seek with each other.
- Binary stars: There are stars that are gravitationally bonded to each other and can be observed rotating around each other. Looking through the eyepiece one can actually observe changing the relative position between the two;
These three types of observations can be complementary to each other leading to a better understanding of the objects involved. For example – a star was occulted by an asteroid this event carefully recorded by a few observers including one team that had a group of amateur astronomers. When the data was analyzed it was found that the star was actually a binary star and one also got the profile of the asteroid.
Variable stars: There are over 150,000 variable stars are known and catalogued, and many thousands more are suspected to be variable. Some of these are bright enough to be observed with naked eyes. In fact, these bright ones are completely in the domain of amateur astronomers. In 2019 the brightest star in Orion constellation, Betelguese, faded and this was observed mainly by amateur astronomers. For pro-telescopes it was a far too brighter object. There are stars for telescopes with primary of any size, from small binoculars to big telescope.
Since 1911 the American Association of Variable Star Observers (AAVSO) has been a bridge between professional and amateur astronomers. You are strongly encouraged to visit their site < Click here >.
As a starting point in variable star observations, start with the famous variable star Algol, which is well suited for observing sessions of winter months.
For the ‘Beginner’s guide to estimating the magnitude of Algol’ <Click here>
Occultations: Occultation observation game is slightly different than the other observations. The event as there are called are predicted well in advance. The event lasts for less than a minute. Regular observations of the lunar occultation can be carried out from the terrace of your home and you may have to travel some distance to observe the event.
Since 1983 International Occultation Timing Association (IOTA) has been promoting observations of occultations. Do visit their site < Click here>.
Double or Binary Stars: This is a different kind of game. Part of binary star observations are also covered by AAVSO but what we really mean here are two stars seen very close to each other. Their separation and direction from each other might change in time. In this case, the stars might be gravitationally bonded to each other. Or the separation between the two is just fixed. It might just be that that the stars happen to be just in the line of sight.
Many of us also regularly check the double stars to assess the combined quality of the telescope and the sky. The brightest star in Gemini, α Geminorum or Castor is a beautiful double star, the magnitude of stars are 1.9 and 2.9 and the stars are just separated by 3.3″. If you can see the stars or in astronomical parlance resolve the stars then you are sure that you have good observing conditions.
Check out this excellent article in the Sky and Telescope < click here >
On these pages, we are trying to address how amateur astronomer or students from India and neighbouring countries may take part in such observations.
Page contributed by Arvind Paranjpye (paranjpye.arvind@gmail.com)