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AAVSO - Variable Stars
The American Association of Variable Star Observers (AAVSO) brings together amateur and professional astronomers around the world to promote astronomy and the observation of variable stars. Its mission is to collect and archive stellar observations, support scientific research, education, and communication, and enable the scientific community to participate in scientific discovery.
Variable stars are stars whose brightness varies over time, either regularly or irregularly. While all stars change to some extent during their lifetime, variable stars are defined as stars that exhibit significant and noticeable variations in brightness. Most variable stars are pulsating variables, in which the outer layers of the star pulsate and the temperature changes.
I decided early on to start observing variables with Slooh's remote telescopes and the willing member got a guide, as the hobby involved more than just taking a picture. The picture does not need to be processed, but the apparent brightness, or magnitude, of the star in it must be measured and reported.
In practice, this is done by astrometrically determining the coordinates of the star and comparing the variable star to nearby stars whose magnitudes do not vary.
Since AAVSO is the most significant reporting database for variable star enthusiasts, the guide advised to use AAVSO's tools to perform the measurement, and this in turn required additional studies.
But it wasn't long before I got the green light from Slooh and became a member of AAVSO. My absolute favorite target is SS Cygni in the constellation Cygnus, where the AAVSO database contains observations dating back to my grandfather 's birth year of 1896. So far, I have reported about 15,000 observations using Slooh, AAVSO, and my own telescopes. The title image shows the light curves of observations from the summer of 2025.
AAVSO VPHOT
The most essential tool at AAVSO is the VPHOT application, which produces a detailed analyzed report from the astrometrically resolved image, which can be saved to the database.