MESSIER INDEX - NGC INDEX - NAME INDEX
Date September 20, 1998
Time at end of first CCD image 20:49 PDT
Time at end of last CCD image 20:53 PDT
Observing Location: At home on the drive way
Observation of object: M21 is a small irregularly open cluster with few stars.
Sky transparency: 5.2 (Magnitude of the faintest star visible with the unaided eye in Ursa Minor)
Notes: Image taken over Portland, Oregon, U.S.A. sky glow.
Moon sets at 19:28 PDT on September 20, 1998
Astronomical twilight ends in the evening at 20:51 PDT on September 20, 1998
Astronomical twilight starts in morning at 5:11 PDT on September 21, 1998
80 mm aperture refractor telescope and CCD Cookbook Camera
CCD image time: 4 -60 seconds images added together
CCD dark calibration frames: 4 - 60 seconds dark frames
Use Test patterns to calibrate monitor brightness, contrast, height and width
© 1998-2003 David Haworth