You don't need a weatherman to know which way the wind blows... The NWS issued storm advisories for the San Francisco Bay Area. Something cooking for later in the evening with the full brunt Monday - even possible thundershowers. Yowser! I love thundershowers and lightning. Especially lightning - what a rush of photons!.

Anyway I also love observing the Night Sky. And you don't need a weatherman to tell you that storms and observing don't go together too well. Skies were fine in Boulder Creek all day. Sure a few streaky clouds, but actually quite fine. Checked the GOES image for the Pac-Con region. Storm system to the northwest. Graceful spiral arm slewing up from the southwest. High pressure region deflecting it north. South was better. And south for me meant "Bonny Doon".

I figure I had till 11:00pm. I was wrong - actually it was 11:30. Then those clouds clinging to the northwest early on began sweeping in overhead. Gave me a good reason to pack up the scopes and take my leave. Home by 12:15 and write up this report. And an interesting one at that.

Apparently, other observers were either discouraged by the weather report or by the presence of a near half-moon. What they didn't take into account was the way those streaking clouds looked. Long coherent shafts of nebulosity. Still air. Good for Jupiter even outside the skies middle third. Good for resolving Iota Leonis. Good for seeing Antares companion - even with the primary some 30 degrees above the southeastern horizon. Good for tiny rilles and craterlets on Selene. Good for comparing Argo and Vicki under 8/10 seeing stability.

And good for sharing the two scopes and a modicum of astronomical experience with a church group of a dozen teenagers. Healthy, vivacious, attractive, intelligent near adults who braved 40 degree temperatures and occasional blustery winds just to look through a couple of small scopes turned on a handful of "old favorites".

It didn't start out so well attended. Nor did I expect to be a tour guide of the Night Sky. I actually sat outside the gate of the privately held Bonny Doon airport and counted 144 breathes before breaking out both scopes and setting them up anywhere I could view Moon and Jupe. For you see, I often do this sort of thing when I have to decide whether or not to do something unpleasant. Count breaths. Lots of breaths. Then once the pre-selected terminus is reached, do what is necessary.

And what was necessary was to setup Argo outside the locked gate and check out seeing conditions. Based on the stillness around me, and the tubular clouds overhead, things were very promising. But wouldn't know how good until I turned Argo on the Moon at 180x. There got a nice clean limb. But there was also a wee bit of tremble around high contrast studies. My best guess 8-/10. Perfect for comparing the 102mm achromat and the 150mm MCT on fine lunar features. And Jupiter? Very nice. Even outside the skies middle third, 7+/10 stability. Dry and still. Oh Boy...

Soon had Vicki setup alongside Argo. And just as I started the comparo SCAC club member Michelle arrived. This confirmed that there was, in fact, a star party scheduled for the evening. Ten minutes later, just as I was getting some sassy views of Selene and Jupe through both scopes, the "kids" arrived. So mind you, please understand that the conclusions I've arrived at of Vicki's performance vis a vis Argo are not well supported by a large number of datapoints. But anyway let me tell you what came to light...

Both Vicki and Argo displayed all Jupe's major and minor belts and zones - including a nicely delineated Equatorial Belt - the Holy Grail of Jupiter viewing. Add to this an obvious GRS rotating in across the disk - with well-defined "socket" and hints of internal detail (at least through Argo). Include a small barge and a faint oval in the NEB plus some belt edge irregularites and you get the sense that all was well with the sky. But not quite so. Argo detected "trembles" in Jupes image where Vicki showed none. Effectively such trembles were beyond the achromats resolution. And these same "trembles" made it difficult to give the edge to Argo on the view - either of Jupe or of Selene.

Speaking of Selene, spent a lot of time with Michelle observing the Ariadaeus and Hyginus cleft regions. These were positioned due west of the terminator along our satellites equator. Splendid presentation! Every time I'd pick out something in Argo though, Vicki would also reveal it. But not quite as sharp at 192x as Argo at 180x. And like Jupiter, no visible tremble, nor occasional "high contrast image twinning". Argo's skies were not Vicki's skies. This proved out later when resolving Castor. Vicki showed a pair of clean airy disks with single diffracts. While Argo's 50% smaller airy disk was tough to pick out within each bright stars spurious image. The pairs spurious images had expanded to include the first diffraction ring. And such a diffraction ring would normally lie just inside Vicki's airy disk had the two scope views been superimposed.

On this fine evening, also turned the scopes on Posidonius. Detail much finer than the previous evening. Both instruments cleanly resolved the "Double-Mound" west of Posidonius A. Quite a trick for a four inch scope. One that requires 7/10 seeing through Argo. However, Argo has gone much deeper during especially splendid nights of seeing. And neither of the two very small craterlets seen near the Posidonius eastern wall was resolvable this occasion.

I asked the kids which scope gave the better view of the Selene. By acclamation, Argo. I asked them which gave a better view of Jupiter. Again by acclaim Vicki. Vicki was also voted most popular in viewing the Castor pair. Now it is a well established fact that a six inch MCT, despite obstruction, behaves like a six inch when viewing lunar features. But the fact that a 4 inch achromat - and not an apochromat - could win out on Jupiter is rather astonishing. Or is it? To my eye the achromat gave higher contrast views of Jupiterean "macro-features". - Things like belts, bands, etc that include extended fields and regular outlines. No question about it, such features appeared darker and more contrasty. BUT embedded micro-features were tougher to resolve. The interior of the GRS was more obviously mottled in Argo. While the "socket" circumscribing that same feature was easier to detect in Vicki. White ovals and barges were often picked out in Argo first, while the EB was first noticed in Vicki.

As in previous comparisons, matched magnifications - not exit pupils. This means that Jupiter was more luminous to the eye through Argo. This reduced the contrast of extended features. But the scopes greater resolving power did a better job of picking out small ideosyncracies within those features. Finally had I actually matched exit pupils - say the optimal .7mm in both scopes, Argo would have boasted 210x while Vicki 150x. At such magnifications, fine details would have been lost through Vicki while macro-features may have gone either way. (Thinner belts would be disadvantaged while thicker ones would be even more contrasty.) Meanwhile at 210x, Argo's Jupiter would have dimmed and even more micro-features revealed.

So the "kids" liked Vicki's Jupiter - and so did I. A four inch scope is just about optimal for this planet. Optimal because such scopes incorporate less turbulence in the image, while providing just the right balance of illumination and contrast. Could you time transit events with it? Sure but not as many. Would you get those once in a lifetime blow out views when the sky is incredibly steady? Probably not. Solid consistent performers them unobstructed diffraction-limited four inchers...

Sometime before the conclusion of the comparo, a lovely young lady unlocked the gate and allowed all our cars into the parking area. Michele and I carefully ported the assembled scopes to the observing area. Though both scopes were mounted the same. Argo is easier to carry than Vicki, but I let Michelle carry the latter. Tells you what my own preference is in the two scopes...

With the comparo behind us, I led the kids on a tour of a few old favorites. Bodes Galaxies, despite Moon, gave high contrast views in Argo (at 52x) and Vicki (40x) respectively. Some of the kids had trouble seeing the galaxies, but this turned out to be due to the fact that I'd framed them in the same field and the kids were accustomed to looking at the center - not the perimeter - of the FOV. My bad, centered on the "edge on". Very nice.

One of the kids had been to Lick Observatory to look through the 36 inch. On that occasion the Sombrero had been viewed. So I turned Argo thereon. - A little tougher for the kids than M82. Showed them the "Ghost of Jupiter". Even at low power they could pick out the "bright bluish bloated star" next to the tiny sharp ones in the field. I showed them Praesepe (in both finder and main tube). Also made a quick check of the 12.7 star through Argo - holdable on moderate aversion. Exceptional with the Moon so close! Calculated transparency (ULM) 5.0. So point sources not bad even some twenty degrees from a near half-moon.

On to Cor Coroli - one of the kids noticed another double due east (as my driveless mount drifted). Thence to M3 which showed incipient resolution in Argo but only a condensed blur in Vicki. Finally, Michelle and I turned up the "Great One" - M13 - at 95x. Smashing! No 4 inch can possibly show this cluster so well on a decent night of seeing. Easily a hundred pinpointy stars - even that 12th magnitude yellow one first noticed last week through the 30 inch at Fremont Peak.

The kids then packed it in. Numbers dwindled throughout the evening. First a dozen, then half that. Adios amigos y amigas...

I hung for awhile. Stowed Vicki away in the hatchback. (Argo is superior in every way for deepskying.) Resolved Iota's faint blue companion. The secondary's airy disk just kissed its electric blue primary's one and only diffraction ring, trailing slightly south of east. Turned the same magification (380x) on Antares. Got a "wobbly" look at the fine green star due west of the primary's second diffraction ring. (Bright stars - when they resolve as disks - get two and sometimes more rings through Argo.) Wobbly because the wind was up and a SkyView Deluxe mount is barely satisfactory for either scope when things are still...

Made the drop down from Spica. Easily caught Omega Centauri. Spent about fifteen minutes watching dozens and dozens of faintly resolvable components "wink" at me. Interestingly, the sky was still enough (as evinced by the quality of focus on brighter field stars) but low sky position robbed the brightest 9th magnitude members of much in the way of their native luminosity.

Of course, I checked the King of Rings. Could hold the 12.3 magnitude star direct at 72x while the 12.8 could be seen with slight aversion. (All this calculates to 5.3ULM some 40 degrees above the horizon - well away from the Moon and through 7/10 stability skies. Can you tell I like this observing site!)

And oh yes. Moon? What Moon? Storm? What Storm?

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