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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Sequences of Mars images acquired on April 8 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 several normalized original frames. The true color images are the result of the composition of 30 images in different lights.

Number of frames per image:

• B filter: 10 frames
• V filter: 10 frames
• I filter: 10 frames
• True color with B V I filters: 30 frames

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:

• 3.0 sec with B filter (centered at 420 nm)
• 0.4 sec with V filter (centered at 530 nm)
• 0.1 sec with I filter (centered at 820 nm)

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