Specifications

Illustration 20: Flat field represents the
telescope/camera response to uniformly
illuminated field
Illustration 21: Fully calibrated image
with dark frame subtracted and applied
flat field
CCD image calibration is described in detail in the SIMS User's Guide. Refer to
the “Introduction to CCD Imaging” and “Calibrate Tool” chapters for
calibration description in theory and in practice.
Color Images with monochrome camera and filters
Color images are definitely more appealing than black and white ones. It is also
easier to gather more information from color images – for instance it is possible
to distinguish which part of the nebula is emission (red) and which is reflection
(blue). But astronomical cameras are only rarely equipped with color CCD
chips from number of reasons. The color and monochrome chips are discussed
in the SIMS User's Guide – refer to the “Introduction to CCD Imaging”
chapter.
Although the G2 CCD camera is equipped with monochrome CCD chip, it is
definitely capable to capture color images, at last when the internal filter wheel
contains RGB filters. Instead of shooting single color image, three images –
each for Red, Green and Blue colors, must be obtained and combined. This
process is not suitable for fast moving/changing objects, but astronomical
objects usually do not change so fast.
Taking three images and combining them is undoubtedly more complex
procedure than shooting simple color image. But using of monochrome chip
brings so important advantages for astronomical usage, that bothering with
multiple images is definitely worth the effort:
40