SF Observing, Tuesday 4/15
By Matt Tarlach

After finishing my taxes Tuesday night, I took out the Ranger to do a little lunar observing. It was a little after 10, and the moon had already begun to sink toward my neighbors' rooftops. Waves of "slow seeing" crawled across the image, making the surface of the moon appear like a cratered ocean. The undulations were so slow and wide that they did not seem to obscure much detail, but after a few minutes of viewing they did start to make me a little seasick! (or should that be see-sick?)

After taking a short break I swung the scope up to Mars, without expecting much. To my surprise, the sky near the zenith was in much better condition, and the disk of the planet held rock-steady in the eyepiece of my 70mm scope. The only problem was wind buffeting, which was making the little tripod-mounted scope dance a bit, but during calm periods the view was very nice. At 140x (7mm Nagler+2x barlow) the polar cap was immediately visible, and after a few minutes I could make out some dark markings in the northern latitudes. Then I saw something that really got my attention: a brighter area on the disk of the planet, near the trailing limb. The orientation of my scope gave a perspective similar to the one I had through Jay's 90mm Vixen at Fisher last weekend, and this bright spot was close to where we had seen Nix Olympica that night. I knew that Tharsis and Olympus Mons would not be in the same location as they had been at about the same time 4 nights earlier, but otherwise had no idea what I was seeing. I did remember, this time, to make a sketch immediately after observing while the details were still fresh in my mind, so I could compare it to maps later and understand what I had seen.

Today I finally got a chance to get online and check the various Mars maps and images available at the Marswatch, JPL, and ALPO sites. The Mars ephemeris at Griffith observatory revealed that the central meridian at the time of my observation had been around 170o. Based on sketches of ALPO observers showing the same area, I am pretty sure that the bright region that got my attention was Elysium. The sketch that resembles what I saw most closely (though with much finer detail) is at: http://astrosun.tn.cornell.edu/marsnet/gif/alpo/mars.970125.gif

The dark northern markings closer to the meridian must have been Propontis, which appeared much larger to my eye that they are on most of the maps and images. The dark areas showed more prominently with a red 23A filter, and both the polar cap and Elysium were enhanced somewhat by an 80A light blue. Haze was also visible at the East and West limbs, along with (possibly) very faint dark markings south of the equator.

Two things I have learned from my Mars observations over the past few weeks:

You can really see a lot with a small telescope, if it is of good quality. Most guidebooks relate that a 60 to 80mm refractor will reveal the polar caps, and Syrtis Major, but not much else except at favorable oppositions. I guess most of those books were written before the development of modern refractive optics!

And, experience counts for a lot. If I had enjoyed the same view four weeks ago, I probably wouldn't have noticed anything but the polar cap and some smudges. Being aware of the need to make a sketch to record the observation is also clear to me now.

After getting all I could out of Mars for the evening, I turned my scope upward into Leo to track down some of the double stars described in the April Sky & Tel. I've found that doubles are neat objects for city astronomers, as the skyglow does them little harm and they are easy to find and observe with a handy, small telescope. The article in Sky & Tel highlights a variety of both close and easy doubles that contrast in color and/or magnitude, and viewing them was a lot of fun. I encourage anyone who hasn't done so already to check 'em out!