Three Evenings in December

THREE EVENINGS IN DECEMBER

A Few Winter “Small Wonders”

On the 28^th of December, 2008, I found myself checking the Clear Sky Chart and seeing nothing but deep blue squares for the next three days. This is a rare enough situation, even in the desert southwest. What made it priceless was that I was in the midst of the University of Arizona’s winter break, when I could take the time to set up and observe on weeknights. I could not get out of town to enjoy this windfall under dark skies, so what I could see through the trees in my back yard would have to do. For a change, I decided not to let my location put me off. For an observing list I employed Tom Trusock’s Small Wonders series, which provided me with a variety of deep sky objects to view, some of them old friends and some new to my eye. My intention was to pick a constellation and observe everything in it that appeared in its Small Wonders installment, but I underestimated how much new growth our robust mesquites put on in the past year. A couple of the constellations I meant to cover came up short, lost in the trees. What I managed to see, however, made all worthwhile.

All but one of the eyepieces used for the following observations are from the Orion Stratus line. For the sake of simplicity I have recorded only their focal lengths, rather than repeatedly typing ‘Stratus.’ The other eyepiece, a 40mm Paragon, is noted when used. The magnifications involved are 48x (21mm), 77x (13mm), 125x (8mm), 200x (5mm) and 25x (40mm Paragon). The telescope used, and affectionately known as the “Three-legged Newt” (Newt to its friends) is an equatorially mounted Newtonian reflector, 203mm aperture and a 1000mm focal length (f/4.9) sold by Orion Telescopes as the SVP 8EQ. (SQM stands for Sky Quality Meter, a device used to measure sky brightness, and the Pickering scale for measuring seeing conditions was employed.)

The First Night

28 December 2008

Pickering 6

SQM 18.75

I started with the constellation Andromeda and for not the first time observed Almach (gamma Andromedae), the double star alleged to give Albireo a run for its money in terms of color contrast. (To my mind it does no such thing.) Splitting it in the 21mm was easy enough, but the color contrast really didn’t stand out until I bumped the magnification up to the 8mm. Tom Trusock points out a similar affect in Small Wonders when he discusses Almach, and my experience with Almach is similar to his: little or no contrast at 48x, but notable contrast at 125x. In the 8mm the primary had a distinct ruddy-golden hue, while the companion star was a spark of pale, ashen blue, rather than white, as noted in Small Wonders. This is not the first time my observation of a double star has not precisely matched what I have read about it, color-wise; it’s actually a commonly reported experience. I only worry if other writers see something as orange, and I see blue, or some similarly large discrepancy.

I was first shown Mirach’s Ghost by a local club member several years ago. Had I found it on my own, I might have dismissed it as a reflection of Mirach (beta And). I’ve viewed this galaxy a few times since, and was pleased to discovery this night that I can see NGC 404 from my back yard. In the 21mm it was hard to tell if I actually saw the galaxy, or was tricking myself because I knew where it should be. It took the 8mm and averted vision to be certain it was there. Of course, under suburban conditions (with the glare of the bright star nearby) I was doing little more than detecting the pale glow of the distant galaxy On the other hand, observations I’ve made of this galaxy from dark sky sites are not exactly rich with details. The star and the galaxy in the same field of view gave me something to think about. The bright ruddy gold star was, by the standards of the universe, practically in my backyard, while that wisp of spectral light near it was the combined light of billions of stars as bright or brighter, muted by an enormous gulf of space. Consider the perspective provided by the sight of an entire galaxy outshone by a single nearby star, and what that perspective says of the depth and scale of cosmic distance. It boggles my mind every time.

Messier 31 is an old friend, the first galaxy outside the Milky Way I ever observed through a telescope. I can find and observe the core region of M31 from my backyard, but other details generally elude me. The fuzzy star-like image of M32, resembling nothing so much as a rather faint globular cluster, was easy to pick out tonight. M110, on the other hand was almost impossible to see using the 40mm Paragon. Switching to the 21mm and sitting quietly for a while, I could see M110 with averted vision, doing a little better with the 13mm. For all that it is technically the brighter of the two, I actually found it easier tonight to make out NGC 404 (Mirach’s Ghost) than M110 go figure.

My next target was the open cluster NGC 752, which when I found it in the Paragon proved difficult to see clearly. Stepping back and looking up the length of the OTA I discovered that I was trying to observe it through the outer twigs of a mesquite tree. In astronomy as in fishing, there always seems to be one that gets away. More than one, in this case, since the Small Wonders article discusses more objects in Andromeda than I was able to see through the tree.

Auriga, however, was well up into the eastern sky, an area that I can observe easily from the back yard location. One of the things I like about the Small Wonders series is the way the author makes a point of discussing distinctive stars in a constellation Capella (alpha Aurigae) in this case. Capella isn’t a visual double, has no ‘ghosts,’ and isn’t part of a cluster. In the 21mm it was just a star, but a very bright and beautiful star, blazing like a speck of molten silver, with that breath catching purity of color only stars possess.

The first Small Wonders DSO I decided to go after in Auriga would have been a new one for me, but for some reason I could not convince myself that there was a star cluster where the charts say NGC 1857 should be. Nothing really stood out to my eye in the field of the 21mm. I tried to out-stubborn the situation, but in every observing session the clock, quite literally, is ticking. Instead of spending precious time doggedly pursuing an object I just was not finding (or seeing), I decided to do a bit of research later and give it a go some other time. And so, on to another new (to me) object, NGC 1907, in the vicinity of M38. This time it was quite clear that there was an object present in the form of a faint grey patch of light just visible in the 21mm. I worked my way up to the 8mm and had a reasonably good look at a few tiny stars embedded in a mottling of not quite resolved starlight. The few stars I could resolve were seen using averted vision, and took some time and watching to detect. Going by the comments in Small Wonders, I was doing well to get that far! I was left with the distinct impression that this cluster is an object worth revisiting when I find myself under dark skies and away from the suburban glow.

It turned out that I had not given up on NGC 1857 soon enough. The time and energy I could spare for this last minute, unexpected observing session ran out. It had been a busy day and I’d started out a bit tired. It was time to go in, open a few books, and address the mystery of NGC 1857.

The Second Night

29 December 2008

Pickering 6

SQM 18.96

On night number two I was a bit better prepared and was able at last to observe the star cluster NGC 1857. I looked up the cluster in question in several resources, read Small Wonders for Auriga more carefully, then slapped myself on the forehead and went out with the 40mm Paragon in the focuser instead of the 21mm Stratus. The lower magnification and wider field of view (a bit over two degrees) brought the mini-Cassiopeia asterism mentioned (and illustrated) in Small Wonders into the picture, and that made all the difference. Using the asterism as a guide, and the low power eyepiece, I finally picked out a haze of faint light associated with a pair of stars, one brighter and redder than the other. In the 13mm I could just make out a sprinkling of faint stars in the vicinity of that pale orange star. More magnification (the 8mm was as high as I went on this) made the gathering of stars more obviously a cluster, with numerous relatively faint pinpricks of light visible in the vicinity of the brighter duo. There were elusive hints of structure to this demure stellar gathering, as if the stars were not arranged uniformly across that little patch of space. Once I had the cluster in view it seemed sort of obvious. How did it escape me last night? Maybe I was standing too close, so to speak, using the 21mm. I also did not use the crooked asterism that should have guided me to the star cluster, and was surely more than a bit off the mark. Sometimes it doesn’t all come together the very first time. Patience is tested and persistence pays.

I celebrated my little breakthrough by visiting old friends, the three Messier open clusters in Auriga: M37, M36, and M38. First M37, a cluster of fairly bright stars grouped into pairs and trios that are themselves gathered into short, curved arcs. The brightest star is almost but not quite centered in the cluster, and has a gold cast to it. I seem to recall reading somewhere that this might be a foreground star, and not part of the cluster proper. I’ve observed this one any number of times, but tonight I had my best ever look at it using the 13mm. The combination of magnification and field of view made this an impressive sight. An old friend seen in a new way. It was worth a long look, and I took one. The longer I look at such an object, the more structured and detailed it appears. I eventually nudged the Newt a bit west and found M36 easily enough, and found that the 13mm was once again the best fit. M36 looks looser, coarser, and more spread out than M37, with a dozen or more fairly bright, and uniformly bright to my eye, stars arranged in pairs and trios, these arrangements being in clumps rather than loose chains. The area behind these most prominent members was a field fairly rich with stars that gradually blended into the star field around the cluster. Another nudge brought M38 into the field of view, and yet again the 13mm ended up my eyepiece of choice. M38 is the least spectacular, perhaps I should say most subtle, of this trio. Its individual stars are not as bright as those of its near neighbors, but seem more numerous, with looping chains of starlight and something of a dark lane running more or less through the middle. M38 always seems strangely remote to my eye, as if something much brighter had fallen to a great depth in dark water.

Next was NGC 1664, an object that left me wondering how its discoverers knew they’d found an open star cluster. I went back and forth between the 21mm and 13mm eyepieces (the Paragon provided no real advantage in this case) and with the help of the description in Small Wonders was able to conclude that the very loose splash tiny stars actually constituted an object. It was a pretty view through the eyepiece, but an impatient observer, sweeping a bit too quickly, might not realize a cluster had passed into view. A pair of brighter stars flanking the cluster (and appearing in the image included with Small Wonders Auriga) helped me to be sure that I was looking at the right place. After looking at it for a moment my eye picked out the shape of a speckled sting ray gliding through dark waters, its slightly curved tail trailing behind. Afterward I discovered that this cluster is sometimes called The Kite Cluster. That I saw an animal instead may have something to do with who I was cheering for in the 2008 World Series.

Small Wonders lists the planetary nebula IC 2149 as a challenge object. I decided to risk spending a portion of my limited time tracking it down and observing it anyway. Ironically, it proved far less of a challenge to locate than NGC 1857. Having 8 inches of aperture at my disposal helped, of course, revealing it as an ‘unfocused star’ even in the 21mm. By the time I worked my way up to the 5mm it was obvious this was no star, but the puffed up remains of one. I couldn’t help thinking Herschel’s descriptive name for this sort of object is very appropriate. The 5mm with an OIII filter made the nature of the object obvious, and gave the impression that it is ever so slightly oblong in an east to west direction, but revealed very little else about it. And yet it was a very satisfying experience to tracking it down and see it for the first time.

My intention for the evening was to finish the list of Small Wonders in Auriga, and I had done so. In the process I’d run another evening out, a consequence of spend so much time on each object. But before I called it quits I put the Paragon back in the focuser and paid both M45 and M42 brief visits. The seeing was once again very good, and so the bright blue-white gems of the Seven Sisters burned with exceptional clarity. The cluster fits into the Paragon view with room to spare, a splendid sight, Tennyson’s fireflies free of their silver braid. That generous field of view also allowed me to view the entire scene of M42 in a glance, from NGC 1981 to iota Orionis. M42 was a ghostly bird shape in space, a bird in flight making a tight turn by partly closing one wing, with a tiny cluster of diamonds on its breast. The diamonds were spilling away. I could see a couple of them rolling down the closed wing.

The Third Night

30 December 2008

Pickering 6+

SQM 18.93

I did not get out as early as I would have liked, and so missed the chance to explore Perseus. The only item listed in Small Wonders that I observed in Perseus was M34, another old friend. I used the 21mm to both find and observe the cluster, which appeared in the generous field as an aggregation of fairly bright and widely scattered stars. The stars seemed to me to be arranged in sets of widely spaced pairs. This is a bright, if not exactly crowded cluster, one I’ve found easy to at least detect using my 8x42 birding binoculars. I’m told some people can pick it out naked eye at a dark site, something I have not been able to do. That was as far as I could go with Perseus, as the constellation had already mostly disappeared behind the branches of a tall mesquite. But I had a fallback plan, and implemented it by opening my binder full of Small Wonders printouts to Orion.

I would have put the Newt on alpha Orionis (Betelgeuse) even if the star had not been included in the Small Wonders write-up. As I hinted briefly back on day one of this ‘trilogy’ the purity of light and color of bright stars holds a powerful attraction for me. In the eyepiece Betelgeuse looked more golden than red to me, with the red fading slightly if I increased the magnification. Strangely enough, it looked redder in the binoculars than it did naked eye or through an eyepiece stuck into the Newt. Ruddy orange with eyes and telescope, more distinctly red in the binoculars. A curious effect, and one I am not able to explain.

From there I went to beta Orionis, brilliant Rigel, and absorbed photons of pure blue-white fire for a change of pace. Conditions were good enough that I thought I’d see if I could peer past the Newt’s diffraction spikes and pick out Rigel’s companion. I thought I could make the split in the 13mm, but was sure of it with the 8mm. The air was so steady that I decided to backtrack, once I’d picked out the companion’s location, to see if I could find it at lower magnifications. In this way I was able, after sitting patiently for quite some time waiting for intermittent moments of extra-stable air, to split the pair with the 13mm. The 21mm just couldn’t do it. Back to the 8mm, then, and a brief contemplation of the huge magnitude contrast between Rigel and the tiny, faint spark beside it. There did not seem to be much of a color contrast, the companion seeming white to my eye, but in the glare of Rigel it’s hard to be sure.

I’ve looked at and split delta Orionis (Mintaka) with almost every telescope I’ve owned over the years, and many of those telescopes of childhood were of pretty poor quality. This is an easy double, but no less attractive for all of that. For one thing the setting, especially in a wide field eyepiece, is quite pretty. The pair itself consists of a roughly second magnitude star of clean white hue, with a chilly bluish 6^th magnitude companion. I never went higher than 21mm; I found myself enjoying the wider view too much, and the star was split handily enough at that magnification.

Collinder (Cr) 69 came next on the Small Wonders hit parade, a cluster that I’ve pretty much ignored over the years, outside of the occasional sweep with binoculars. In fact, I’m not certain I knew, before I started working on Collinder’s Catalog, that this was a cluster at all. I first observed it as an object about a year ago using a 102mm refractor. With the acquisition of the 40mm Paragon, I find myself able to do it justice in the Newt. The initial impression comes from the triangle asterism formed by phi 1, phi 2, and lambda Orionis, the latter being a moderately close (and pretty) double star. A third faint star gives it the look of a triple star, but none of the references I own include it as a part of the set. Phi 2 Orionis, it turns out, isn’t part of Cr 69, and removing it from consideration left me with a strung out star cluster. My general impression was of three fairly bright stars in a row (including phi 1 and lambda Orionis) with a fainter trio strung out between lambda and phi 1. There was a loose scatter of faint stars just to the east of those forming the line. Tom Trusock writes that this isn’t a particularly bright or rich cluster, and I agree, but it certainly is an odd one. In volume one of the Night Sky Observer’s Guide (NSOG) the suggestion is made to use an OIII filter and averted vision, with a telescope of at least 8 inches aperture, to pick up a haze of nebulosity around the brighter stars. I tried this, but no such luck.

No eyepiece I own could do justice to Cr 70, the star cluster that exists in and around Orion’s Belt. Binoculars do the trick, though. I’ve always known that the binocular view of the Belt was spectacular, but I did not always know that this was an open star cluster. In my 8x42 binoculars the Belt Cluster is a star field to rival that of the alpha Persei Association, and like the latter cluster there is little, in a suburban sky, that hints of such an assemblage of stars. The first time I looked at the sky around the Belt through binoculars I experienced a sort of Galileo moment, in which a set of lenses revealed to me that there was more here than meets the eye. Three bright stars are suddenly the brightest members of a swarm of a hundred stars (at least) of various magnitudes. It’s a dramatic and, when seen for the first time, surprising transformation.

As I surveyed the stars of the Belt Cluster the nightlife of Tucson made itself known. No, not the college students (all safely home for the holidays) coyotes. From somewhere north in the not-quite darkness I heard them singing. They were probably in the bed of the Rillito River, a couple of miles to the north. I always pause when I hear them, marveling that such wildness can live in the city.

Of course, I spent most of my time tonight looking at M42 and its neighbors through various eyepieces, with and without an OIII filter. The view with the 40mm Paragon still boggles my mind talk about getting the Big Picture! I also sketched a variety of these views, but found that none of the sketches really worked out as I hoped. There was something about the amount of detail that came to me as I sat there tonight that rendered the sharpest pencil little more than a blunt instrument. These sketches record the observations well enough, but they don’t do the objects sketched justice. Visual observers who clutch pencils in the night know what I mean. The seeing was once again quite good, so I decided to seek out the E and F stars of the Trapezium. The 21mm just resolve the basic quartet, something the 13mm did to much better effect. While using the 13mm I had a peculiar experience. A faint star appeared from within the nebular glow and zipped smoothly away. It was, of course, a satellite that had passed across the nebula unnoticed until it emerged, so to speak, into the darker sky just off the Fish’s Mouth. The illusion of a star escaping M42, however, took me by surprise. I pushed the magnification a bit more and with the 8mm could see the E star pretty easily. The 5mm gave me fitful glimpses of both E and F, and during several exceptionally calm moments both of the fainter stars were clearly visible. I’ve read various accounts of the colors of the stars in the ‘Trap,’ but all of them look bluish or white to my eye.

I spent relatively little time on NGC 1981 tonight, and most of that involved considering the name Tom Trusock gives this cluster in his article. He called it “the Crown,” and wondered what a crown would be doing hanging from Orion’s belt. I think I have a better idea: might this not be the pommel of Orion’s sword?

I have only ever seen M78 from a dark site, but since it was on the list, and conditions were so good, I thought I’d give it try. The two stars that give the nebula a ghostly face-like illusion were easy enough to find, and if I used averted vision there definitely was nebulosity around them, but no view (filtered or not) really gave a clear impression of what was there. M78 is definitely a nebula that shows poorly if there is much light pollution around. The same is very true of NGC 2071, which should have been in the same field of view in a couple of the eyepieces I used. Of this nebula not a trace was to be seen. Also missing in action was the planetary nebula on the Small Wonders list, NGC 2022. I know I had it in the field of view, but could never be certain that I actually saw it.

The last call ended up being yet another new-to-me open star cluster, NGC 1662. Tom Trusock recommends being sure of its location with a finder scope before going to the eyepiece, since it can be lost among the stars when “larger” apertures are used. Apparently, the Newt doesn’t count as “larger.” I managed to find NGC 1662 quite easily using the 21mm, and observed it with that eyepiece as increased magnification made it harder to pick out the cluster from the star field around it. I found it to be an odd little cluster, a sort of knotted string of stars that quickly trailed off and blended in with the background. It was an appealing object, and one I will surely observe again before Orion sinks into the west for the season. In the meantime, the cumulative effect of three nights of altered sleep cycles caught up with me, and it was time to wrap up this third and longest session. I fear I will never be known as an all-night observer.

Three clear and chilly suburban nights in a row had seen me seated beside the Newt, revisiting old acquaintances and discovering new sights. Although all of it had been under clear skies with better than average seeing conditions, it was obviously not a dark sky adventure. Just look at the SQM readings I put at the beginning of each evening’s accounting. And yet I tracked down, observed, and had satisfying encounters with a variety of deep sky objects. In recent years I’ve become so spoiled by having dark sky sites relatively nearby, living where I do, that I haven’t bothered with DSO observing while home, preferring the Moon, planets, and double stars that show up well in suburban skies. The city around my backyard does impose limits on what I can observe (and the trees really don’t help!), but these three evenings served as a clear reminder that I don’t need to wait for the Moon to have an excuse to spend time at the eyepiece, at home.