Mars 2/11/10 9:09pm

11 February 2010

There have been precious few opportunities for us to do astronomy here in Seattle for the past few months. A new baby in the family, and three months of almost constant overcast weather have impacted the amount of real telescope time we could put in. A few nights ago we had an unusual (and temporary) window in the clouds, so I took my C9.25 and shot a few sets of Mars video.

Seeing was average, with a persistent fast high-altitude atmospheric distortion. Transparency started out good but increasing got worse throughout the evening as clouds moved back in. Later in the evening this meant I did not have enough light at 1/60 second exposures and had to go to 1/30 second exposures. Unfortunately, the result was that the images later in the evening were not as sharp.

Notice the blue haze to the right and left of the planet surface. This is the evening haze on Mars, which is part of the normal weather pattern.

You may be wondering why this image is so much better than my previous efforts. Equipment and procedures were essentially the same. On 11/14 at 6pm Mars was only 8.8 degrees in size, and it was at 60 degrees above the horizon. The difference in size is due to Mars being close to opposition right now. Opposition essentially means that Mars is the closest to Earth that it gets for now. Weather also plays a factor and a night of steady seeing makes a big difference.

Location: Seattle, Washington USA
Date and Time: February 9, 2010 9:08pm (5:08 UTC)
Mars apparent diameter: 13.7”
Mars altitude above horizon: 53 degrees
3500 frames each R,G,B
Imaging Source DMK21AU04.AS @ 30fps with 1/60 sec exposures
Televue Powermate 2.5x
Astronomik Type IIc R,G,B filters

The following is one of other images of Mars I took later the same evening. As I mentioned earlier, the conditions degraded throughout the evening. This image was taken with the same setup as above, but with 1/30 sec exposures. You can see the effect of the slower exposures as the image is blurred along the direction of the wind (up/down relative to Mars) in the upper atmosphere.