Fremont Peak Mars Night, Aug. 16-17, 2003

by Peter Natscher


A few us up at Fremont Peak's Ranger Row area and one's at the FPOA Observatory offered a visiting crowd very nice celestial views of the brighter summer sky objects and stunning views of Mars. The weather conditions leading into the night time started off very good for general observing before the moon rose and continued to improve later on for Mars. I was accompanied by Rich Neuschaffer with his 180 EDT and Rashad Al-Mansour with his 4" TeleVue Genesis.

The seeing for us was very good at the onset of twilight at 8:30 pm. With my 10" Mak-Cass, I observed a few brighter doubles (epsilon Lyrae and Alpha Scorpius) to check the seeing above. Both doubles looked beautiful as tight points of colored light with even diffraction all around. Antares tiny partner, 6 arc-secs away, did appear a cool blue-green in color easily separated from its blazing orange-red primary star. The sky transparency was very high, as the CSC had forecast, with the air around us being 15% RH and 65F, and with no wind--my favorite Fremont Peak summertime scenario. By 9 pm, the Milky Way was appearing distinctly with stars overhead visible down to mag. 6.3 in Cygnus and Lyra. This nice darkness remained until moon rise a few hours later on. Taking advantage of the pre-moon rise darkness, I located a few special H400 open clusters, emission nebula, and galaxies in Cepheus and Pegasus to sketch and log. Even though the moon washed out the skies darkness, the Milky Way continued to be prominently seen alongside the bright moon for the rest of the night.

I started my Mars observations by 10 pm when Mars was high enough to show some surface features. I was using my Zeiss/Baader Bino's with 12mm Tak LE's and 10mm Zeiss Abbes (385X and 463X respectively), and trying out a variety of filters (Baader Planetery, Sirius Planetary, Red, and light blue) on them. The winning filters were the Baader Planetary (narrow band filters). They pass enough of the Martian planetary color to keep the view natural and actually enrich the color a bit. They do this by lowering the UV, albedo brightness, and planetary atmospheric haze yielding more contrast of the delicate Martian surface features.

By 12 am, the observers up at the observatory announced that they had seen Mars' brighter inner moon, Phobos, with the 30" telescope as it made a fast maximum western elongation. I immediately took interest in seeing this myself with my 10" Mak-Cass. Within 5 minutes of their announcement, I too was able to see Phobos intermittantly using direct vision with bright Mars in view also. I was using a 10mm Zeiss Abbe eyepiece at 370X. Tiny and twinkling Phobos lie 25 arc-sec (one Mars dia.) to the west of the yellow glaring planet. I couldn't see Phobos using my bino's at 385X, but could see it easily with one eyepiece (both the 10mm Zeiss Abbe and a 12mm Takahashi LE). Using either single eyepiece gave a brighter, sharper, and higher contrast view than using the bino with its two eyepieces along with a prism beam splitter. Phobos became more easily seen during the subsequent hour as it remained ~20 arc-secs west of Mars and as the seeing improved. Spotting Phobos with direct vision and without the use of an occulting bar in the eyepiece last night was the high-point of the Mars evening for me. Rich Neuschaffer's 180EDT also caught Phobos during this same time span. The superior seeing conditions were the primary determinant in our ability to spot Phobos along with the premium quality of my 10" Mak-Cass and Rich's 180EDT telescopes. Sharp seeing is a must to discern Phobos' tiny point of light. The larger aperture of the 30" telescope did make seeing Phobos easier than with my 10" and Rich's 7" telescopes. Then there were people who couldn't spot Phobos in my 10" Mak-Cass even though I and a few others could. The condition of an observers eyes also plays a part, too. If the seeing became a slightly soft, Phobos would disappear immediately. It's reminiscent of my many attempts (successful and unsuccessful) in spotting tiny Enceladeus or Mimas alongside bright Saturn.

I packed up at 2:30 am after being fully satisfied with an evening of observing up at Fremont Peak in the summertime.