Montebello Report: May 22, 2002
by Jeff Barbour
The month of May is hard on observing in the San Francisco Bay Area. To be correct, not all observing. Certainly sky transparency is better than that of winter's "cold and damp". But stability often takes it on the chin. Warm days lead to cold nights. The result is a "heat engine" of image-quality robbing turbulence.
Of course I've been hammering on this turbulence theme for a while now. But I'd like to lay the groundwork for the evening's adventures at Montebello. For you see, I still sit on the fence as far as observing there is concerned. Sure, there is a very expansive horizon. And yes, twenty-two miles is not a long way to go compared to - say the sixty needed to get to Fremont Peak. But 13 mile distant Bonny Doon Airport is closer, has almost as expansive a skyline and, seems almost immune from "Spring Fever". BUT outside scheduled SCAC events, the airport is off-limits.
Now I haven't done a complete job of listing the virtues of observing out of Montebello. For there are a lot of "perks" that come out of observing there. For instance, son Eric just got his learner's permit. And unlike his brother before him doesn't get a whole lot of chances to drive. So frequent trips to Montebello would be very helpful in this regard.
Though Eric wasn't around last night, I went anyway. One reason? That expansive horizon. Opportunities to revisit all those doubles in Ursa Majoris and a sinking Leo are now on the wane. And although stability out of Backyard Boulder Creek is perhaps slightly superior to Montebello, the backyard locale is "vertically challenged": Tall redwoods to southwest and one "green and growing" such tree in the middle of the property.
So I a setoff for MB and arrived with Sun still well clear of the horizon. Setup the ST80 Pup with solar filter. At 40x, a good deal of solar limb boil present. One single sunspot and four groups could be seen. That single large spot trailed to the east along the solar equator. One group each fanned out toward the polar regions. A very populous sprawl of fine spots moved away from the central meridian to the west. This particular group included a "fine linear scratch" that appeared as though someone had dragged a key along the sun's golden-orange painted surface. Seeing such a scratch was a first for me. Suspected it to be a trail of fine spots. One more closely aggregated than another linear group located more toward the Sun's north pole. Poor stability prevented me from resolving the scratch at higher magnifications.
About this time Merak rolled into the lot. I recalled his post on TAC about turning up. We greeted and discussed the "scratch". Neither of us have any real experience with solar viewing, but we both agreed that this was not anything you would normally expect to see... As the evening progressed Merak proved to be a "cornucopia" of lunar knowledge. Seems his background in terestrial geology has well-prepared him with a fine understanding of the forces that shaped the Earth's "cast off" remnant in space.
Phil turned up shortly thereafter. Merak headed off to setup his 5 inch ETX, while Phil turned on the Giants game and went about the ludicrously absurd task of mounting a 70mm "brass monkey" Televue Ranger on a Losmandy G11 mount. OK, laughter aside, you can certainly say that the little ranger gave "rock steady" views of the Moon soon after assembly!
Speaking of Selene, as soon as the sun set removed the white tubed ST80 and installed "Black Beauty": astro.geekjoy's "project scope". "Vicki" is a 102mm F9.8 Vixen Optical achromat. A scope which has both delighted and surprised me with fine views of just about everything it's been turned upon. And tonight, Vicki would be retracing 150mm MCT "Argo's" steps through those 17 pairs of close and disparate doubles located in UMI, UMA and LEO. (See 2002.04.22.2.html) But before getting duplicious, there was still a bit of light sky to contend with. This all meant a three quarter's Selene to pay homage to...
About this time Rich turned up with his 6 inch APO. Before going to the trouble of setting up. Rich was kind of interested in getting a sense of the seeing. In checking out the Moon, it was pretty clear that things were less than inspiring. As opposed to views had through Vicki at last Saturday's SCAC Bonny Doon star party, quite a bit of low and high frequency oscillation was evident. To my eye, and through a four inch at 192x - gave the seeing 6-/10. But historically (during Spring Fever) stability tends to improve throughout the night. Tonight would not prove to be an exception. Within a half hour or so, Rich started unpacking the equipment.
With a preliminary seeing check behind me, swept about the terminator looking for an "objet d'eve". And like everyone who turned up (Merak, Phil, Rich, James, and Alan) spent quality time with Gassendi. Gassendi - that old ruinous crater crowned by a tight group of central peaks. Invaded from the south by the basaltic flows of Mare Humorum. Scratched to the north by twin parallel cuts. Sliced by several deep rilles. Home to a variety of small craterlets. "That Old Character" - Gassendi.
Throughout the evening had numerous monocular and binocular views of Gassendi through Rich's sixer. When seeing was, say 6/10, the only difference between the six and the four was how high your observing stool was. (Not really, the APO, like Argo, gives the Moon a natural bone yellow color as opposed to the more flagrant yellow of the achromat.) However when things temporarily stabilized, (say moments of 7+/10 seeing), the sixer would begin to flex its muscle. Views of numerous very minor craterlets and sharply defined rille structure would emerge. Such features were possible at four, but sharper in the six.
But this wasn't a blow out. As has been said by many "there is no magic scope". Only "magic skies".
So off to doubles. A quick look at Gamma Leonis showed near twin, perfect golden airy disks with single walking diffraction rings. Certainly stability had improved! This was 8/10 seeing through the four incher - though anything larger (such as Rich's six or Phil's now well-mounted C9.25 had trouble showing anything other than spurious images.) Meanwhile under the Moon's intense glare, the sky overhead could barely reveal stars unaided to magnitude 4.5. What would have been a 5.0 sky without the Moon, limited the 4 incher to a calculated limiting telescopic magnitude 12.0 at 192x. (Sorry, no Praesepe check this evening but surely "12.7 star with moderate aversion".)
Now as this report is getting a bit long, let me summarize doubles results as follows:
The following two pairs proved hopelessly unresolvable through Vicki, Argo (previously), Rich's sixer, or Phil's nine and changer:
Name Star RA Dec Comp Mag1 Mag2 Sep PA U2000 Spec
HJ 2477-AB IOTA UMA 08 59.3 48 02 AB 3.9 9.5 4.5 24 70 A5
BU 105-AB KAPPA LEO 09 24.6 26 11 AB 4.6 10.4 2.4 211 143 K0
Both these pairs have primarys brighter than magnitude 5.0, sub-five arcsec separations, and magnitudinal deltas greater than 5.0. Such secondaries are some 50 times dimmer than their primaries. Add to this a brightish sky, a little haze, some light scatter, and its easy to see why they might turn up MIA. Somebody please prove these are actually doubles!
The following five pairs have not been resolved either by Argo or Vicki:
KU 1-AB 16 43.0 77 30 AB 6.1 9.4 2.7 184 11 F2 ALSO HU 917
STT 199-AB 09 20.7 51 15 AB 6.1 10.2 5.7 133 44 F2
HO 377-AB 51 UMA 11 04.6 38 14 AB 6.1 12.6 8.2 250 73/ 106 A2
BU 919 11 59.3 33 09 6.0 12.0 4.5 16 107 K0
STT 523 39 LEO 10 17.3 23 06 5.8 11.4 7.6 299 144 F5
This group is a mixed assortment of closish disparates and wider faint-secondary pairs that may eventually prove resolvable. Under the best conditions it's just possible that Argo may succeed. While one (KU-1 in UMI), may also be solvable through Vicki under the best of skies.
The two pairs that followg have been resolved by Argo, but not Vicki:
KUI 54-AB CHI LEO 11 05.1 07 20 AB 4.7 11.0 3.6 268 191 F0
STF 1536 IOTA LEO 11 23.9 10 32 4.1 7.3 1.3 141 191 F5
The Chi Leonis resolve hung right at the limits, and is probably beyond a four inch. Meanwhile Iota Leonis-B is simply too dim to be resolved with a four inch scope. The secondary is simply too close to the classical Dawe's limit of matched pairs.
Vicki and Argo both have successfully resolved the following seven pairs:
STF 1306-AB SIGMA UMA 2 09 10.4 67 07 AB 5.0 8.2 3.0 3 23 F8
STF 1523 XI UMA 11 18.2 31 32 4.3 4.8 3.0 129 106 G0 Also 53 UMA
STF 1524 NU UMA 11 18.5 33 05 3.7 10.1 7.3 147 106 K0
STF 1543-AB 57 UMA 11 29.1 39 20 AB 5.4 8.4 5.5 358 73/ 106
STF 1695-AB 12 56.3 54 05 AB 6.0 7.9 3.7 280 48 A2
STF 1450 49 LEO 10 35.1 08 39 5.8 8.5 2.2 157 190 A0
STF 1552-AB 90 LEO 11 34.7 16 47 AB 6.1 7.4 3.4 208 147/ 192 B3
Of the above, STF 1552 (90 Leo) was very difficult for Vicki last night. The gap has clearly closed on this binary and right now probably lies very close to Dawes limit (1.2 arcsecs) for a 4 inch instrument. All I saw last night was a faint fuzz projecting off the primary to the south and slightly leading. There was no clear definition. Meanwhile the view of Nu UMA was also beyond Vicki last night - but not beyond 5.8 ULM skies at Bonny Doon. This is most definitely a "disparate on the edge" for a 4 inch instrument.
At Montebello also got a chance to check out that sweet, mildly disparate pair (STF 1695) south of Epsilon UMA through Phil's C9.25. Through the 4 incher, the secondary appeared "lavender" in color. Meanwhile, the greater concentration of light possible with the nine and changer showed it to be made of pure gold...
One pair observed through Argo is yet to be observed through Vicki. That pair:
STF 1555-AB 11 36.3 27 46 AB 6.4 6.8 0.6 143 106/ 107/ 147 A3
has widened considerably and could be as much as 1.5 arcsecs currently. This pair deserves more scrutiny and I hope to get a calculated separation on it soon.
Finally several of the above pairs have proven historically resolvable through the 80mm "Pup". These include:
STF 1523 XI UMA 11 18.2 31 32 4.3 4.8 3.0 129 106 G0 Also 53 UMA
STF 1543-AB 57 UMA 11 29.1 39 20 AB 5.4 8.4 5.5 358 73/ 106
During the course of the evening, also captured thinline resolve magnifications for Xi UMA through Vicki. At 120x clear distinction of the pair achieved while at 85x not. Referencing http://astro.geekjoy.com/calcs/sepCalc.html gives a calculated separation of 1.92 arc seconds. Not bad considering the current (2002.42) value is 1.80.
Ah but let's finish our story. As mentioned, there are other "perks" associated with viewing out of Montebello that will probably ensure many happy returns on my part. For you see, the place is frequented by a certain class of fellow denizens whose companionship under the Night Sky is most welcome and always worthwhile. There is more to amateur astronomy than poking a scope at the sky. The hobby lends itself quite nicely to socialization. Get the right bunch of folks together and numerous laughs, joys, banter, and insights, can flow almost unabated. Often the most unusual examples of cosmical phenomenon can be adumbrated. Consider why craters on the moon are almost always circular for instance. No, it's not because most asteroid impacts vector perpendicularly out of the void. It actually has something more to do with the way "Aqualung" might demonstrate the effect of shockwave propagation.
Hehehe...