Throwing Big Glass at the Night Sky : Observing Report

in #steemstem6 years ago (edited)

What happens when two local astronomers take 25x100 binoculars and a 12" GoTo reflector out under NELM 5.0 skies?

Answer : DSO hunting, cigar smoking, and streetlight warfare, that's what.

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Casual Shoot-out : 25x100 binocular versus 12" GoTo reflector

Location : South Central Florida

Sky (CSC ratings) : Transparency (above average 4/10), Seeing (good 4/5) (this was one of the better nights in recent memory. Very clear, very transparent, and very stable. Little or no twinkling stars for most of the evening. Zero clouds. Humidity was relatively low, although it climbed higher as the night progressed.)

Last night I met up with fellow amateur David Dale for a casual stargaze from his backyard. Although his local skies are a full magnitude darker than mine, we had a bright sodium street lamp to contend with. This lamp is a recent installation and I can only imagine : a) how dark it was before this unshielded lamp showed up, and b) how frustrated David must be to have this new sun blazing down on his observing spot. I brought my black-out blinds though, and once erected, we had a dark slice of ground directly behind the fabric. The blind shielded us from the worst direct effects of the light, and then we set up our equipment.

We had a low shot of the horizon in all directions, down to an average of 10-degrees or so. The only direction which had any noticeable skyglow was SE towards Tampa. In that direction, there was an annoying blister of light that reduced the LM by a full magnitude or more. Other than this and the glaring street lamp, I envy David's local skies. What a difference 15 miles makes, which is how far David's NELM 5.0 backyard is from my own NELM 4.4 backyard. At the zenith, David's sky is closer to 5.4 or 5.5, which really presented a noticeable difference. The amount of naked eye stars visible is staggering compared to my usual Tampa sky, in fact, I lost Hercules and other familiar constellations for a few moments and had to break out the trusty planisphere to orientate myself.

I helped David hoist the ~45 pound optical tube of the 12" Orion Intelliscope onto it's base, and then he began to orient the GoTo computer by finding known stars. While he was doing this, I setup my AstroWood parallelogram mount and 25x100mm Skymaster binoculars. I also had my 15x70mm Skymasters nearby for later use. David also had a nice pair of Nikon 10x50 binocs, although I forget what model. At any rate, by the time we had everything setup, it was pushing 10:00pm and Scorpius was starting to rise out of the SE skyglow. While David was preparing to find targets in the upper region of Scorpius, I wheeled the big binoculars around and started nailing favorites from memory. M13, M5, M4, and Jupiter. By this time, David had M4 located in a low power ep (~40x) and it appeared quite ghostly - due to the lack of contrast against the washed out skyglow of Tampa. It was unfortunate that my hometown skyglow is in the same direction that Scorpius and Sagittarius rise, but at least the skyglow only extended up to about 8 or 10 degrees. So as the night progressed we would re-visit some of these early targets. At any rate, M4 was not impressive in either of our instruments. M80 did present a more compact and bright view.

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Ok, on with the specifics :

M4 : did not impress in either instrument.

M80 : at low power in the 12" (40x), it appeared small with noticeable brightening at the core. At higher power (140x) it partially resolved into a nice splattering of fairy dust, shot through with pin points that emerged from the glow.

M80 : in the 25x100 binocular, this object was "there", but nothing to get excited about. Under averted vision, a hint of brightening was visible in the core, but not much.

M13 : at low power in the 12" scope, M13 was bright and large. Even at 40x, the outer edges appeared to resolve and take on a distinct grainy appearance. David then dropped in a high power ep (I forget which, but around 200x) and WOW. I have never seen M13 fully resolved, so let me say again : WOW. I cupped my hands around the focuser/ep to block out stray light and just gawked like a kid. Countless individual suns emerged across the entire face of the glob, and they teased the eye with subtle patterns and colors. Long arcing strings and clumps of suns made pleasing patterns that seemed to shift and change as one's gaze focused from one area to the next. Occasionally a colored star would be wink through the predominate crowd of white, giving a hint of orange or red. I could have stared at M13 for an hour or more through this ep, given the chance.

M13 : in the 25x100 binocular - large diffuse cotton-ball with noticeable brightening at the core under averted vision. No resolution of course, and nothing to write home about.

M57 : Another first time for me - I actually SAW the ring. Through David's big dob at ~140x, the ring shape was clearly visible. A ghostly little donut that exhibited some traces of texture in it's form. The predominate color was a lime green shot through with blue, that turned gray towards the edges. The central star was not seen.

M57 : in the 25x100 binocular this object was a tiny gray ghost, barely visible against the background sky. No hint of the true nature of this object was seen. For all intents and purposes, it looked like a fainter version of M4. Just a lighter patch in the sky.

Jupiter - At ~60x, both equatorial bands were easily seen, and some of the polar-region bands were visible under "tricky" vision. Although the seeing was stable, I am learning (as a novice planetary observer) that seeing detail in planets is a hit-and-miss affair. After a couple of minutes of looking, I could definitely see a creamy texture to the disc, not unlike creamer poured into a cup of coffee and swirled around with a swizzle-stick. The GRS or other major detail were not seen at this time. 2 or 3 moons were visible around the disc (I forget exactly how many, because I was not concentrating on them).

Jupiter - My usual view of Jupiter, nothing to rave about. A tiny disc, about 1/3 or 1/4 the size of David's view. The two major equatorial bands were seen, as were 4 moons around the planet. Not hint of coloration or texture was seen, beyond the most subtle impression of an overall creamy color. It was nice to see all 4 moons arrayed around the Jovian giant. David's view, while much more impressive, suffered from a smaller FOV and thus the larger context of the moons was lost.

The Coathanger looked really nice through the 15x70 binoculars. In the 25x100, the context was lost with the outer members of the cluster, and in the scope it was nothing to get excited about. To me, it looks about as much like a "coathanger" as M11 looks like "wild ducks", but enough people must see a coathanger for the name to stick, so I'll go along with it.

We then spent some time hunting around for some of the Ursa Major galaxies. Unfortunately, even at NELM ~5.0 and using a 12" scope, these are some challenging targets. In short, we were suffering from a lack of contrast and the ill effects of the insufficiently-shielded street lamp nearby - not to mention the cars passing by every 5-10 minutes which prevented full dark adaptation. After some careful searching, all we managed to do was see a single galaxy pairing in the low-power (~40x) eyepiece. I forget which galaxies they were, but I don't think they were M81/82. At least I hope not, for these were very disappointing. They looked like a pair of fuzzy stars or stars with associated nebulosity. 2 pin points of light with a tiny diffuse halo around them. David's impression describes them well - a snakebite, a pair of dots. With this performance, we decided to leave the galaxies alone for the evening and concentrate on bright nebulae and star clusters.

Now it was passing 11:00-11:30pm and Scorpius had risen well out of the SE skyglow into darker skies. Also, the top of the teapot of Sagittarius was now visible in the same region that Scorpius waded through earlier - the blister of LP around Tampa. It was tempting to wheel the big guns around to Sagittarius, but I decided to wait another half-hour to an hour, when the teapot would be free and clear of the LP blister. So in the meantime, while David was hunting for Scorpius targets, I turned the 100mm binocs around to Cygnus. Cygnus was now riding about 20-degrees up from the ENE horizon, and was begging for wide-field attention. Now is where the big binoculars come into their own. Nothing beats a wide-field, low-power, bino view of the Summer Milky Way. Wow. Wow. Wow. Cygnus is one of my all-time favorites for casual panning and scanning, and that is exactly what I did, for several long minutes. I wheeled around from Deneb to Albireo, taking in thousands of stars along the way. Packed fields of apparent doubles, isolated colored jewels amidst the blue-white proliferation, and subtle hints of dark lanes against the layers of pixie dust. It's awe-inspiring and staggering in it's grandeur. It really makes one sit back a moment from the eyepieces, lean back in the chair, take a big draw of the cigar, and say "WOW". The vastness of the universe becomes so apparent when viewing the sky this way. Around this time, I decided to swap out the 25x100 binoculars for the wider field of the 15x70 Skymaster. Rather than remove some the counterweights on the parallelogram, I simply loosened them and moved them closer to the binocular. After a little tweaking, I got the right balance and took a tour through Cygnus again, at lower power. I really enjoyed the wide 4-degree swaths of sky. After calling David over for a few looks, I capped off the binoculars to shield them from the growing humidity and we went back to looking through the big dob. On a whim, we took a look at M56, due to it's proximity to the Cygnus region. It wasn't terribly impressive, so I will omit the description except to say it was reminiscent of M4 early in the evening.

This was the first time I have seen Sagittarius since last year, and it was well worth the wait. My first target was the star cloud, M24. Unfortunately, I did not bring my charts (I find the SA2000 to unwieldy to use in the field), and I could not locate it from memory. We could have used the GoTo to find it, but David was already off and running, gobbling up targets. In short order, we saw (at various magnifications) : M6, M7, M11, and M20.

M6 : presented nice low-power views through the scope and the big binocs. It has a nice boxy form that I like, but I honestly don't count it amongst the most impressive Sagittarius targets.

M7 : this one got a "Wow" from David through the binoculars. A packed collection of bright jewels. One of the nicest open clusters in the sky, in my opinion. In the scope, the view was bigger and closer, but a smaller field prevented the proper "framing" of the cluster. I would give a slight edge to the binoculars on this target.

M11 : I don't really know why, but I really enjoy this cluster. I don't see any ducks, wild or otherwise, and it defies easy description in my book. It has a nice organic shape that tempts me to play connect the dots. The low-power views were equally impressive through both instruments. There is no edge to using high-power in the big dob with open clusters, they simply dissolve into widely-spaced stars and lose their form.

M20 : the cluster associated with the Triffid was easily seen and enjoyed through the binoculars, but seeing the nebula itself was difficult. Under sustained averted vision, it would pop out and subtlely reveal itself. The image scale was quite small at 25x, but the nebula was visible as a ghostly form. Through the big dob, the nebula was brighter and showed more form, but no texture or coloration that I could see.

We also bagged Omega Centauri through the big binoculars! That was my first time viewing this object. It looked like a large patch of spilled milk on the background sky - roughly 2 to 2.5 times bigger than M13. We could not view it in the scope because the blackout blind to protect us from the streetlight happened to just BARELY block a line of sight with the King of Globs. Rather than move the dob and re-orient the GoTo, we decided to resolve it under magnification next time around.

During a lull in the action, I decided to take a 25x binocular sweep through the Sagittarius and lower-Scorpius regions. During my sweeps, I stumbled across the beautiful form of M17, the Omega/Swan nebula. This nebula was plainly visible through the binoculars and to my eyes, it resembled a slightly-damaged Pi symbol, I say "damaged" because one "leg" of the Pi was missing. I called David over and got another "Wow". The nebula was grayish/bluish and looked nothing like the Hubble photos, but it was the best I had ever seen it. From my NELM 4.4 backyard, the nebula is yet another "ghost". Here, last night, it was very striking. Through the big dob, the view was even more impressive. While the view through the big scope was brighter and more detailed, the binocs presented a wide-field view of the Summer Milky Way enshrouding the nebula on all sides. Nice. Again, slight edge (in my book) to the binoculars.

Something struck me last night, and I wish to mention it here. I was pleasantly surprised at how well the 100mm binoculars stood up against the larger aperture of the 12" reflector. The perceived difference in image brightness was subtle on most targets, with the binoculars seeming to present an almost equally bright view. Sure, the big scope blew the binocs out of the water on globulars and other faint fuzzies, but the binoculars were not completely outclassed as I had expected. On bright nebulas and open clusters, the big binoculars earned a bit of respect from both David and I.

Clear dark skies to all....

MikeG

Photos by Michael Gilmer (Galactic Stone)

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You definitely need to get to darker skies! But that is a nice report anyways. One of my favorites is to split the star Antares, seeing the blue companion is always really cool.

I was always more interested in faint fuzzies than splitting binaries or planetary - which is ironic, given that my home skies are light polluted. It's not very often that I get to observe under truly DARK skies. The last time was outside of New Orleans right after Katrina knocked out the electrical grid. It was the darkest skies I have ever seen. I managed to get in a couple of nights of ad-hoc observing before the lights started coming back on.

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