Specifications

AUTOSTAR CCD PHOTOMETRY 101
Comet Photometry
With each appearance of a new comet, interest in comet
photometry is revived. This is a very specialized form of
photometry, and special filters are usually needed to acquire data
on the gaseous emissions. The photometrist with a UBV or BVRI
photometer can still make valuable observations, however.
Before getting too far into comet photometry, it is advisable to
contact some of the comet photometry experts. (See the
References section.) Also, keep an eye out for any new comets.
You may be the first to do photometry on them.
Stellar Photometry
Stellar photometry is probably the most popular and useful project
undertaken by amateur astronomers. A great many stars have light
that is not constant. These form the class known as variable stars.
Projects ranging from just timing of eclipses to detailed filter
photometry are well within the capability of the amateur
astronomer with modest equipment.
The variable light output from stars can be caused by several
phenomena. Basically, there are three types of variable stars:
intrinsic variables, eruptive variables, and extrinsic variables.
With some variable star projects, only timing of the period of the
cyclic variation in white light is important. Others require filter
photometry and careful calibration of the system and comparison
stars. The following is a list of characteristics of the different types
of variable stars:
Intrinsic Variables
The intrinsic variables exhibit light variations caused by internal
phenomena. The star may pulsate (e.g., Cepheid variables). This
pulsation may be of a long period (Miras) or a short-period
pulsation, semi–regular, or irregular. Also, a relatively new group
of stars, known as RS CVn variables are believed to have large
star spots (similar to sun spots only much larger) that travel around
on the surface of the star. These spots are cooler than the rest of
the surface, so as they migrate they cause the star's brightness to
change.