stars. We don't have any sophisticated equipment for measuring
and monitoring the brightness of these stars but using an
inexpensive video camera attached to our 8" telescope we have been
able to come up with a method of measuring relative brightness.
Starlite is a program designed to calculate the brightness of one
star (the target star) as a percentage of a reference star.
The program was written in MS VisualBasic 3.1. You need
vbrun300.dll in your Windows (Windows System) directory to
run this. (You probably have it.)
We have used it to measure the brightness of the variable star
Beta Lyra. Our images where captured from a video camera
attched to an 8", B&L, SC telescope. The camera is an ASTROVID
400
purchased from Adirondack Video - check their home page at:
http://ourworld.compuserve.com/homepages/AVAastro/
Starlite is a simple utility that looks at each pixel
in a grey scale image,calulates the "RGB" value as a
measure of brightness and adds them up. (You can tell
by the interface that I didn't spend too many late
nights putting this one together.)
To use the program the star images must be grey bit maps (.bmp).
The images must be "cleaned up", meaning that all of the
background must be black (RGB value = 0). Most graphics
software make this fairly easy to do. I use Corel Photopaint4.
If you fail to do this then any background brightness will be
added to the star's brightness.
I have included 4 pairs of images from the summer of 1996.
These images have already been "cleaned up".
Beta Lyra is the target star and Vega is the reference star.
The file bl1.bmp goes with v1.bmp, bl2.bmp with v2.bmp etc.
To see dates and times the images where captured, view the
image bldata.gif.
To calculate the relative brightness of a star,
first load the target and reference stars by
clicking on the corresponding button and selecting
a BMP file. Click on START to calculate relative
brightness value. (ie. load bl1.bmp for the target star
and v1.bmp for the reference star. This will provide
a relative brightness number for Beta Lyra/Vega
at 20:10, EDT, Aug 04, 1996.)
The pixel coordinate boxes show the x and y coordinates
of the pixel being read (0,0 is upper left corner).
The RATIO box displays the value Target/Reference.
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Four images of the variable star Beta Lyra
with the bright, stable star Vega.
Images captured on four nights in August, 1996