Visual Observing

There are three main stages for making an observation of a variable star:

1. Finding the star
2. Estimating its brightness
3. Submitting the estimation to the AAVSO

Finding the Star

It's easy to find one star in the sky - the Sun! The rest of the stars? Not so much. At first finding a variable star can take some time. However, soon it becomes second nature. What may take 45 minutes your first time outside will eventually take just a few seconds.

Again, we recommend newbies start with the 10 Star Tutorial. It spells it out for you pretty easily and includes all the charts you need.

First thing you need to find a variable star is a star chart, which is like a map of the sky. The AAVSO has an online customizable star chart making program called the Variable Star Plotter. Pages 3-5 describes with illustrations how to use a star chart.

 

Estimating its Brightness

To measure a star's brightness, simply compare it to other stars in the sky. Those other stars are called comparison stars because you use them to, well, make a comparison. (Astronomers sometimes name things using weird conventions, but this time it's pretty clear.) Astronomers have carefully measured the brightness of the comparison stars and assigned them a number according to the brightness. The smaller the number, the brighter the star.

In this example, Betelgeuse will be close to the same brightness as Rigel, which has a 01 brightness number assigned to it. So one may estimate Betelgeuse at brightness 01.

In this example, Betelgeuse will be close to the same brightness as the star labeled 21. So one may estimate it at brightness 21.

In this example, Betelgeuse is somewhere in the middle between the 01 and the 21 comparison stars. So one may estimate it somewhere between the two numbers, say, brightness 11.

This process is called interpolation. For more information on it, read chapter 6 of our Variable Star Astronomy (VSA) curriculum.

Submitting an Estimate

This is the easy part! It's also quite fun because this is where you can see where your observation compares to everyone else's. First, you need an observer code. This is a unique code that we assign to you. All observations you ever send to us will forever be tagged with that code so we know it came from you. Click here to apply for an observer code. (It takes about 1-2 business days for the staff to process the request.)

Once you have an observer code you'll be ready to submit your observation. Later this summer we'll have an input form on the CitizenSky web site so you can just login here and submit your observation. Until that is done, you can go here to submit your data. That is the full data entry web site that most AAVSO users know and love. Even though it is pretty easy to use, the version we're making for the CitizenSky web site will be much simpler.

After your observation has been submitted you can look it up in our database to compare your observation to everyone else. There are two good ways to do this. The first is by looking at our Quick Look file. Type in the name of the star you observed and you'll see all recent observations we have received. Yours should be near the top of the list. The other way is with the light curve generator. This plots a visual graph of the observations we have received. Simply type in the name of the star you observed in the name field and your observer code in the (yep, you guessed it) observer code field. Click Submit and you'll get a plot data for the star. Your observation will be surrounded by a black box.