Aug 23, 2003: Mars

Tracy Davis and I have been spending the past few weeks figuring out how best to take pictures of the planet Mars with our equipment. Tonight, we managed our best images so far. The setup was:

• Meade LX-200 12-inch telescope
• eyepiece projection, with Meade 12.5mm eyepiece
• Wratten #25 red filter
• SBIG ST-9 CCD camera at shortest exposure setting (says 0.06 seconds, but we don't entirely believe it)
• a very crude aperture mask covering about 75% of the aperture

This arrangement provides an image of Mars which subtends around 100 pixels; that isn't quite as large as we'd like (each pixel about 0.2 arcsec), but it does reduce image motion due to the atmosphere and the telescope. We had lots of problems using another arrangement which have about about 2.5 times the image size. This camera has a USB interface, so it's possible to acquire subframes covering Mars very rapidly; that's very important for focusing and centering at these high magnifications.

We took several series of 100 or more exposures. Tracy used the Registax program to combine many exposures, discard the bad ones, and do a little sharpening. Below is a sample single image, on the left, and the final combined product, to its right.

On the right is a version of an image of Mars taken by Don Parker, shrunk to match the size of our images. You can see that we have a way to go to match the best ground-based pictures! Go to the Marswatch page and browse through their images page to see some really great pictures.