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Log, Aug 25, 2001

27 people. With a second successive clear night in the offing (unheard of this summer!) excitement was running high in the minds of astronomers as they convened once again at FDO on Saturday night - the last regularly scheduled public Saturday session for the season. By 7 PM Les and Barry had already arrived, and when Doug pulled up moments later Les was already showing the 1st quarter moon to an appreciative couple with a young daughter - in broad daylight!

As often happens at FDO when there's been an afternoon sea breeze, sunset brought on another bought of patchy cloudiness caused by adabiatic cooling. This occurs when the moist sea air, which had been drying out over the much warmer inland, rises into the upper air levels that cool quickly once the sun is gone. The moisture condenses to thick puffy clouds, and for a time it looks like all viewing will be lost! However, as the land cools, the sea breeze is cut off, the air mixes and stabilizes, and clearing often takes place in a matter of minutes. This is just what happened at FDO between 8 PM and 9:30 PM. Periods of thick threatening clouds whizzing by, then a rather sudden clearing that left us in great shape for the remainder of the night!

Note: The moderating effect of the nearby ocean played an important role in our viewing later in the night. Inland areas cooled quickly, and heavy ground fog formed over most of southern New England. (Those with drives home to the north had the unpleasant experience of having to navigate through it.) At FDO, the air stayed just mild enough (due to the ocean temps) to prevent the fog from forming - although we could see it approaching around dawn, just a mile or two inland!

While the clouds did their early dance, Les slewed the big scope from place to place, enjoying whatever views he could. Eta Ophiuci, a double star with two widely separated faint companions was up first. The primary is a very close double star of nearly equal magnitude, now separated by just 0.6" - too close to resolve in the damp air, but a possible test object for the 16" on a better night. The globulars M22 and M54 in Sagittarius were an interesting contrast. Both are large, but M22 is bright and dazzling, whereas M54 is much dimmer and less impressive, at least visually

With fewer visitors we were able to do a bit more exploring of the moon at higher powers, finding the air more steady than on the previous night. Les spent quite a while studying Mars as the moon was sinking low to the horizon. He could see the bright Hellas basin area, and the north polar ice cap. But most interesting was his sighting of Deimos, the smaller moon of Mars, now just 13th magnitude. A bit later, both Les and Doug, using even more magnification, confirmed sighting the larger Phobos as it had emerged from Mars' shadow. It is a magnitude brighter, but much closer to the glare of Mars, so harder to spot. This may well be our last sighting of these tiny moons until Mars' next opposition, the history making approach of 2003.

As the public continued to arrive Doug slewed the scope up to the ever popular M2 in Aquarius - one of the real showpieces of the sky. It is believed that this globular, though rather distant from us, may be the second most massive in our galaxy, exceeded only by the great Omega Centauri. Next we looked at the wonderful M11, the Wild Duck Cluster in Scutum - so rich and densely packed that it looks more like a globular than an open cluster. We zoomed in on the core of this gem at 606X - Wow! A dazzling, almost 3D view! Even seasoned observers like Les and Doug were amazed, as we usually don't close in on open clusters this way. But M11 certainly can take the magnification!

Out in the yard, Barry had his XT8 Dobsonian in high gear, studying one summer Milky Way object after another. Also on hand was Gary (and an observing friend who's name we unfortunately didn't jot down), down from the Boston area with his fine 10" LX200. The early clouds were only a minor discouragement to these guys, and when it cleared it became obvious that a long, fine night was in store!

Gary suggested to Doug a couple of pairs of interesting objects that can be seen in one low power field of view - these had been mentioned in Sky & Tel as excellent targets. They are the galaxy NGC6946 and the open cluster NGC6939 in Cepheus, and the globular NGC6712 and the planetary IC 1295 in Scutum. With the dome positioned as it was (shutter "up") we could only look at the second pairing at that moment, but it was an interesting contrast. NGC6712 is a well resolved, though rather remote globular, as seen in the 16". The nearby IC 1295 was barely visible until Doug added the narrowband nebular filter, which made the round, 13th magnitude planetary much easier to see. We next moved on to the fine circular planetary NGC6781 in Aquila, shining at a moderate magnitude 11.8, and the rather distant globular cluster NGC6934 in Delphinus, magnitude 8.9 and 2' in diameter. Despite its distance, this globular is fairly well resolved in the 16"

At about this time Les had to leave, as he had a long drive facing him early in the morning. Fortunately there were just enough qualified staff on hand (Doug and Barry) to keep FDO open. We always want to have at least two present, just in case of any problem, illness, accident, or something else unforeseen. Anyway, this saved a rewarding night for all those still on hand - it would have been awfully tough to have to close down with such marvelous conditions. And about that sky: after moonset Doug rated it a 9 out of 10. The only better nights we get are when the humidity is lower, and dim M33 becomes a naked eye object!

Moving into Draco, we observed the Cat's Eye Planetary, NGC6543. This very blue-green and bright (8.3) object is shaped exactly like a cat's eye, 22" x 16", and its 10.2 mag. central star was easily seen. Dimly seen in the same eyepiece view was the irregular galaxy NGC6552, at a low mag. of 13.7. About 3.5 degrees to the north we observed the bright spiral galaxy NGC6503, at magnitude 10.2 and 8' x3', but could not make out any dark lanes or other details.

Next up was Lyra, and the always popular M57 Ring Nebula. Doug was hoping to see even fainter stars this night than last, but again could reach no deeper than the 15.7 magnitude star on the western edge of the ring. The central star was again seen, but only intermittently. The globular M56 was next, and this object looks just fine in large scopes like the 16" - well resolved into hundreds of faint points of light, many of them blending into the rich Milky Way background. Just a degree NW lies the dim planetary NGC6765, mag 12.9 and 38" across, slightly elliptical in shape. With no filter it was still easily spotted, glowing in front of hundreds of dim background stars.

Next we spent quite a while with a most challenging object, the remote but very rich open cluster NGC6791 in Lyra. Listed as magnitude 9.5, and 16' in diameter (1/2 the moon's size), the cluster lies 1 degree ESE of 21 Theta Lyra. There is a fine photograph of it on page 1177 of Burnham's Handbook - which would lead you to believe that it is an easy cluster to view visually. (Of course, it was taken with a 48" telescope!). Actually, this is one of the most difficult targets we've gone after recently. Having a scope that places it in view, and a software program to identify the star field certainly helps. But even when we knew just where we were looking the cluster was barely visible in the 16" at 102X. Bumping up the power to 160x, however, began to reveal the many dim stars in the cluster, ranging from a few at magnitude 13 down to scores between magnitude 14 and 15. At 203 power the stars were even more obvious. but the cluster filled the filed of view, making the whole thing look only like a rich Milky way star field. Someday we hope to observe this really tough object in Hank's 20" Dob! Even in that it will not likely look like the photo, however.

Four open clusters in Cygnus were our next targets. NGC6811, near Delta Cyg, is fairly poor, but NGC6819, 6866 and 6910 are all rich, fascinating clusters that are worthy of much more investigation - we're making a note of that now. But what kept drawing us closer was the Veil Nebula. After the wonderful experience that Joe, Satish and Doug had had on the previous night, we couldn't wait to visit this fine object again. Barry and Gary were the new beneficiaries this night - Barry likening the tour to a minibus tour through a candy factory! Doug recreated the experience of the night before - guiding the tour from the PC screen - calling out points of interest as Barry and Gary slid the scope around and about the fascinating maze of light and darkness. This celestial tour with the Oxy III filter is sure to become a staple of future sessions at FDO!

Turning eastward, Saturn was next up, and the views of the rings and moons was marvelous. The planet now casts a distinct shadow on the rings, and we counted 7 moons. Only Mimas escaped our gaze, as it was too close to the bright rings. (It had been seen the previous night.) Earlier in the evening we had looked at Neptune - its moon Triton had moved from the 2 o'clock position the night before down to 5 PM - still remarkably easy to see for a magnitude 13.5 object!

A look into Auriga brought us to the old favorite triumvirate of fine Messier clusters, M36, M38 and, best of all, the fabulous M37 - one of Barry's favorites. Nearby we also noted the cluster NGC1893, easily glimpsed in binoculars, but not an especially impressive cluster in the 16"

Lastly we looked at Jupiter and its marvelously cloud-banded surface. The great red spot was not in view at this hour, and Io was transiting the planet. We tried to spot its shadow without luck, but found out later that it had already moved off the planet's surface.

For the actual last object of the night we couldn't resist looking at M42, just as on the previous night. Now, however, it was still totally dark, so we popped in the Oxy III filter and took a look. Holy Cow! Despite the relatively low altitude (18 degrees) the view was marvelous - Barry had never seen the great nebula in the Oxy III before and was just speechless! Just like the photographs, but better! How many times this fall and winter will this fine object impress and amaze us all?

Barry had been up at this point for a good 24 hours, so it was merciful that the sunrise was fast approaching! Closing up shop at FDO takes two staffers a good 20 minutes - it's not the kind of thing you can rush, and when your brain is catatonic after an all nighter you have to be especially careful! The scope has to be parked, all the gear has to be a5secured and stowed, the dome and shutter repositioned and closed, and all electrical sources switched off and disconnected. So we didn't actually lock the doors and head for our cars until 4:40 AM. Just as he was closing the fence gate, Doug noticed a brilliant Iridium flare high up in the western sky in Aries. "Look at that!" he shouted, and Barry also caught a look at the now fading flare. It had been a magnitude -8 flare in a dark sky! We'd have been watching for it had we ever expected to be at FDO so late for a second consecutive night. We didn't expect that....but of course we were there - it was clear and moonless! Doug figured out later that in one 36 hour stretch starting on Friday evening, he'd been at FDO for 21 hours and on the road for another 5! Insanity of the highest order, to be sure, but he says he wouldn't trade a minute of it!

And so, back to back all nighters brought to a memorable and rewarding close our summer season of weekend openings. Thanks to all who helped to make it possible! Many fine nights lie ahead, of course, and as we work to build our staff there may be other such extended opening programs in our future. Let's hope so!

A word of appreciation to Doug Stewart who wrote at least 90% of this week's log entry. Les Coleman also would like to thank his 3 year old secretary Georgeta Coleman who single handedly turned a 20 minute editing project into a four day event.

-Les Coleman

Leslie Coleman
Author:
Leslie Coleman
Entry Date:
Aug 25, 2001
Published Under:
Leslie Coleman's Log
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