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Log, Jul 13, 2001

93 people: Due to the large crowds of eager public, the time on the 16" was devoted mostly to observing Mars; everyone wanted to see it and the line stretched out the door of the dome onto the lawn for a couple of hours. This grew a little tiring for those spelling one another at the scope (Joe, Les, Doug and Tom), but we aim to please! As a result, however, we didn't get on to any deep sky objects until about 11 PM. Mars itself was a disappointment, mainly due to a large dust storm that is sweeping the planet right now, obscuring many surface details that are often seen. The storm has also lightened the color of the planet itself. Many observers noted that it is now much paler in shade, more of a deep yellow, than its normal orange-red. Later in the evening we did attempt to spot the Martian moons, using an occulting eyepiece fabricated by Ernie Adams, but we had no luck, as by that time the planet had dipped too close to the horizon.

First up on the deep sky list was nearby M4, the huge globular just to the west of Antares. This showpiece often suffers due to its southern location and immense size - extending almost as wide as the full moon. (It is one of the nearest globulars, at about 10,000 light years). Friday night, however, it was wonderfully resolved into countless stars, causing many oohs and aahs from those in attendance. We noted the prominent bar of stars that runs NNE to SSW through the center of the cluster.

Next Joe swung the scope over to the wonderful Lagoon Nebula [M8]. This combination star cluster and bright nebula is so large that only about 90% of it can be seen in the scope even at low power (100X). M8 is an easy naked eye object under dark skies like FDO's, and in large binoculars is a wonderful sight. The 16" reveals the dark "lagoon" area sharply in the center. The nebulosity became even more pronounced when Joe added the Oxy-III filter. What a sight!

With the Oxy-III filter still in place we next looked at the equally famous Omega, or Swan Nebula [M17]. Perhaps no other deep sky object looks in the 16" as much like it's time exposure photographs. Magnificent, with many swirling light and dark areas of fine nebulosity! Don't miss this one if you haven't seen it at FDO!

A bit northwest of the Swan Nebula is the famous Eagle Nebula [M16]. Another star cluster illuminating a wonderful nebulous area, the "flying eagle" shape was well seen by everyone, using the same Oxy-III filter. Many observers have never positively seen the nebulosity before in any scope (it is fairly dim and with little contrast), so this was a real treat!

Just a degree northeast of M17 we observed a fine colored double star that Doug had "discovered" just a night before in his C8. It is designated HD (Henry Draper catalogue) 168815, and consists of a pair of 7.2 and 7.9 magnitude stars about 10" apart. What a fine color contrast, every bit as good as the famous Albireo, but not as bright or as widely separated. Even modest scopes will show this double very well, although the colors (aqua blue and deep orange) are enhanced in larger apertures.

For a real show stopper we next turned the 16" to M22, the third brightest globular in the heavens, and the brightest visible from our latitude. Absolutely jaw dropping in its beauty! Thousands upon thousands of stars like diamond dust building toward a brilliant core. It was difficult pulling the public away from the eyepiece!

Around 11:30 Doug announced to all that Comet Linear was in view in the eastern sky. Clearly visible to the naked eye, somewhere around magnitude 4, it was a fine sight in binoculars, with just a trace of a tail seen in 10x 50's. In the 16" the core was large and remarkably bright. Many faint background stars shone through the comet - enhancing the 3D effect, and the comet's motion against them was obvious after only about 10 minutes.

While still in Pegasus we revisited an old favorite, the excellent M15, one of the finer globulars. This one has an intensely bright and concentrated core - more so than almost any other. Our friend Hank from Woonsocket was down with his 20" Dobsonian. He asked if we'd ever searched for the faint planetary within M15. We haven't, but Hank says he spotted it once with his scope right on FDO's grounds. Perhaps we will do the same one night with the 16"?

Moving westward again to Scutum we next observed the "Wild Duck" Cluster [M11]. It was now after midnight and folks were still coming into the dome for their first views. This extremely impressive cluster never fails us, looking almost more like a globular. Check out the unusual "pine cone" shaped grouping of stars in an unusually dark area of the cluster's SW quadrant.

Just a couple of degrees south-southeast of M11 is the globular NGC6712, shining at magnitude 8.3. This object cannot compare to the brighter globulars, but in the 16" was beautifully resolved to its core. It also sits in an extremely rich star field. Doug had observed it earlier in the week in his C8, noting only partial resolution.

M26, an open star cluster also in Scutum was next, but just as we began to observe it some low stratus clouds started rolling in from the west. This was not totally unexpected (from the forecast), but was still disappointing, as the seeing had been wonderful to that point. But the moon had also risen, so Joe and Doug reluctantly decided to close up early - it was only 1:25 AM! They buttoned everything up (keeping a careful eye on the cloud cover) and left the park at 1:50. And of course, within just a few minutes of driving northward, Doug reported that the skies cleared again, completely. Oh well!

-Doug Stewart

Leslie Coleman
Author:
Leslie Coleman
Entry Date:
Jul 13, 2001
Published Under:
Leslie Coleman's Log
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