It was a night that shouldn't have happened - and, in a way, didn't. The passing of the Moon from late winter's night skies brought the return of the usual observation-averse winter weather. Sporadic rainfall and mostly cloudy skies. Local meteorologists anticipated increased probability of rain throughout Saturday.

With Argo still assembled in the study, I monitored the sky while practicing martial techiques on the workout deck. I was encouraged in this by an inconstant Sun which had managed to thin the clouds overhead enough to show a visible - if not stark - solar disk.

By 4 o'clock large areas of the sky opened up and the prospect of an evenings observation at the SCAC Bonny Dune observing site improved. Five o'clock saw Argo disassembled and packed away into the hatchback. A quick dinner, full thermos of "tea, Earl Grey, hot" and I was off.

By 5:30, and with son Christopher riding "shotgun", was off to Scotts Valley, CA. Took the most expeditious route out. Dropped Chris off and pursued the scenic route back into the Santa Cruz Mountains. As I drove, eaves-dropped on the local public radio station (KUSP FM). "The Earl" was broadcasting a string of "golden oldies". Soon noticed something "progressive" about the evening's playlist. Late fifties "boy groups" phased to early sixties "girl groups". By the time my path lay "up, up, and away" toward the Bonny Dune Ridge, the music started to rock. "Magic Bus" captured my attention. I started pulsing to the primal elements of the call and response of the dialog between the singers, rasp and snarl of electric guitars, and insistent beat of the drums. By the mid-60's music had most definitely changed. And the world would never be the same again...

Approaching the end of Felton Empire Grade Road, I lost track of the music and considered the plan for the evening. Fellow SCAC observer Troy was expected to turn up with his 120mm Orion Astroview achromat. I hoped to get a sense of how well this "oversized Pup" would perform on the Gas Giants. (There should not be any serious issues with deepsky.) Since I originally encouraged Troy to consider this model (over the ST90), I felt personally responsible for the outcome.

The main goal for the evening was to track down early evening studies from the Messier Marathon Observing Schedule. Although I have no expectations of fully participating in such an event, I have the notion that perhaps, maybe, the schedule could make for a nice series of "mini-marathons".

As it turned out, that plan didn't map very well with conditions. The western sky was "frought" with clouds. Early studies from the list were inaccessible. Those same clouds also frustrated fellow SCAC observer Jack who showed up at the observing site not too long after my own arrival. Jack had brought along a pair of 15x60mm binoculars in hopes of locating comet Ikeya-Zhang before it turned the corner and goes combust in the solar glow.

My arrival was preceded by Troy's. Troy had just finished aligning the finderscope and was in process of orienting the mount. By the time I had Argo mounted and aligned, Jupiter and its "five satellites" were in the scopes low power field of view... Why five? As it turned out a single sixth magnitude star had managed to perfectly infiltrate the line created by the four Galilean's...

With a focal length of 600mm (F5) the Astroview 120 has the same set of issues as the ST80mm Pup. It takes a lot of ancillary glass (in the form of a barlow lens) to bump the magnification to anything useful for serious lunar-planetary-double star work. As it turned out, Troy's kit included a single "shorty" barlow. In conjunction with a 7mm eyepiece, the scope could achieve 150x (the shorty is not a true 2x unit).

Despite limited image scale, that first view of Jupiter held both a promise and a curse. To my eye the scope possessed decently-figured and reasonably well-aligned optics. Image flare on focal traverse was detectable - but not obvious. (Collimation was pretty good right out of the box). The planet's limb was well-delineated and it's main belts showed a solid level of contrast. (The amount of spherical aberration was quite acceptable). But chromatic aberration was excessive to the point of annoyance. (In fact the thin magenta glow that traces the limb of Jupiter as seen through the 80mm Pup, becomes a rather large bubble of spurious light in the 120mm.) Troy has three options in this regard: Carefully experiment with doublet air-spacing (as I have on the Pup), live with it as it is, or use an aperture-stop when viewing bright studies.

The effectiveness of this last approach was made exceptionally clear when the Astroview was turned on Saturn with the 43mm aperture-stop in place. No trace of chromaticicm was seen (at the F14 focal ratio implicated by this method). Troy, fellow SCAC observer Dan (who had also joined us by this time - sans FS102mm Takahashi), and I were all very impressed by the quality of the stopped image. Suspicions are that, should Troy experiment with stops in the 70 to 90mm range, he will come up with an aperture that gives the best overall balance of image resolution, color, and brightness on moon and planets. (The best aperture for the Pup in this regards is 67mm - although I am pleased with the Pup even at the full 80mms due to improved doublet spacing.)

To be complete, I must say that Troy's Astroview did a fine job of cleanly resolving Cassini's Division in Saturn's ring system - even at the full 120mm's of aperture. And like the 80mm Pup, it was able todetect the division at 43mms when stopped down. However, image quality of the scope was not the equal of the 150mm MCT on either planet. The jury is out on how much of this shortcoming can be attributed to the scope's excess of chromatic aberration.

As for Argo, Dan was the first to spot it. A small (2 arc second sized) barge lay very close to Jupiter's central meridian. At first Dan thought it might be a transiting shadow - but all four Galilean's lay well clear of the planet. This, plus the barge's location embedded in the NEB pointed to it's being a cloudtop formation - and not a shadow transit. Other Jupiter features glimpsed (under the 7+/10 stability we enjoyed at the time) included a well-defined NTB and a segment of the NTTB north of that.

Saturn also gave a fine view through Argo. Cassini and Encke (the Minima - not the Gap) were visible at 260x (using Dan's 7mm Nagler Type I eyepiece). Several satellites could be seen proximate to the ring system. (Titan lay well distant.) Jack, Dan, Troy, and a friend of Troy's all cycled up to the scope. Meanwhile stars to east and west began to wink out beset as they were by encroaching clouds...

Soon all we had left was Orion to the south and Gemini well overhead. Of course, we could easily spend an entire evening exploring the Celestial Hunter alone. Jack made his 15x60mm binoculars available for views of the M42 region. The bonoculars revealed an amazingly extensive region of nebulosity - far more than could ever be traced out at the luminosity-thinning magnifications seen through larger apertures at higher powers. The view of the M42 region through the two scopes were comparable - with perhaps slightly better contrast seen through Argo. The 150mm made the fifth Trapezium member a bit more obvious than the 120. Trap F, however, was beyond both scopes on this particular night. We also had a look at NGC2024 - the Flame Nebula through Argo. At best, it could be faintly detected along with a sense of the dark bar that divides its two main lobes of nebulosity.

We also dropped further south into the Celestial Rabbit for a look at M79 in Lepus. The cluster - even at a mere 70x - gave hint to a globular narure. For even as the eye moved across it, the faint sparkle of numerous stars were seen...

For these views we installed Dan's "Super-ortho" eyepiece in Argo. This 25mm Bausch and Laumb unit gives high contrast views of superb clarity. It's long eye relief also made it possible for me to leave my eyeglasses on. This allowed us toavoid constant re-focusing as observers blessed with normally-corrected vision and I shared the scope.

Even as impending clouds converged above us, we had M35 and it's fine, 8.6 magnitude line of sight neighbor NGC2158 in the 70x field of view. Paying homage to both, Dan and I discussed the relative merits of bright and faint open clusters. M35 is a superb example of the former. Numerous stars, concentrated toward the core, arrayed in great swirls, and arcs, giving at once a "geometric" and "flowerlike" appearance. The latter, a faint spray of light, luminous, unresolved, nebulous. From some distant vantage (let's say on the far side of "Gemini") there's probably a place where the two cluster roles are reversed and our NGC2158 is the featured cluster, while M35 hangs on the limits of resolution.

Like most things, it's all a matter of "perspective"...

to: top of page

to: Special Observing Reports Page

to: Astro.Geekjoy Home Page

Email: Astro.Geekjoy