MarsWatch 1996-1997

Images of Mars from Astronomers Around the World

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Linking Amateur and Professional Mars Observing Communities

for Observational Support of the Mars Pathfinder Mission

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Sequence of Mars images acquired on 31 January 1997 using a D.30 cm F/24 Cassegrain telescope at direct focus and an ISIS CCD-800 camera
(KAF-400 chip, 768x512 pixels, 14 bit A/D converter). Each monochrome image is the enhanced sum of four normalized original frames. The color images are the result of the composition of 12 images (4 B, 4 V and 4 R).

The enhancement was obtained by

1. Image restoration using the Van Cittert algorithm
2. Fourier filtering using the Butterworth low-pass filter
3. Contrast enhancement using unsharp masking
4. Image enlargement by 50% using biquadratic interpolation
5. Histogram stretching for exposure matching

Exp.times:

• 4.0 sec with B filter (centered at 420 nm)
• 0.4 sec with V filter (centered at 530 nm)
• 0.2 sec with R filter (centered at 610 nm)
• 0.1 sec with I filter (centered at 820 nm)

Authors: A. Leo, G. Quarra
San Gersole` Planetary Group - Florence (ITALY)
U.A.I. - Planetary Section, Mars Program