Wednesday, May 16, 2001

Backyard Observing 5/16/01

The night did not begin with much promise. As the sun set, the true nature of the sky was revealed. Overhead it had looked relatively clear, just some sparse thin bands of clouds, but not much. I was initially so encouraged that I pulled back the tarp from the telescope, did a collimation check (perfect!), and waited for dark. Yet, as the sun dropped below the horizon the view to the west revealed the true nature of its condition, full of light cloud. Disappointment. Still, I held out hope that conditions would improve, so up went the light blind that shields me from much of the nearby pollution. My entire set up time was under 5 minutes. I could grow to like this!

The hours rolled by. 9:30 I checked and the sky looked bright, and there were obvious patches where stars could not be found. 10:10, back out, much the same. Back indoors to work on the computer. Again I checked at 10:45 and thought things looked improved. Whereas I had not been able to hold mag 4.2 Chara (Beta Canum Venaticorum) with direct vision half an hour ago, it was now much easier to see. Skies were close to mag 5 overhead.

I stepped onto La Caja, opened my SA2000, and went to the eyepiece. This is magic, I thought. Just steps out my back door, and I'm engaged in one of my favorite activities. I pointed the scope at M3 and began.

M3 resolved wonderfully at 103X with the 20mm Nagler. Lots of space around the globular to give some perspective. It is fun to "blow it up" with high power, but without empty space surrounding this showpiece, it loses some of its aesthetic appeal. As I looked at the object, it occurred to me this was far from being just a big ball of stars. There is a ring of bright stars that seems to form a boundary that contains the main portion of the cluster. I put in the 12mm Nagler for 177X. Outside the ring are a number of what I term "stragglers"... stars that appear to be part of the cluster, but fall outside the stellar ring "reef". The ring itself should be obvious to anyone that can resolve the cluster well. I was resolving it to pinpoints in the core, or so I thought. Within the ring, the area to the southeast is sparse of stars. The real activity is toward the northwest inner side of the ring. Here the star city jumps to life, becoming a dense roundish mass of stars. They are resolved, and packed tightly, but not so tightly that space between them entirely disappears. This part of the structure sits noticeably off center in the outer ring, touching the northwest inner side. Gazing at the inner ball of stars, it suddenly appears that while I can see stars "to the core"... that the ones I can see are on my side of the core. The core itself is a glowing haze of gray/white, perhaps half the diameter of the dense pack. It is inside, and suddenly the entire cluster takes on a 3D appearance. Those stars that appeared to be "at the core" are not... they are part of the sphere of inner mass stars surrounding the actual core. This was an amazing view. I also enjoyed looking at the perspective, knowing the cluster sits 30,000 light years distant, and the surrounding stars in the field are all neighbors to us, virtually all under 1,000 light years from home. How amazing to see these individual stars in M3 and witness an object that is real, exists today, yet is so old as to predate written human history.

Next I moved to M51, expecting to see nothing but a couple faint smudges. While the view was not amazing in detail, there were no obvious spiral arms, the M51 and NGC 5195 were plainly there with very direct vision. I could detect a bit of elongation, N/S in M51 and E/W in 5195. While the "smudges" were much more than I am accustomed to from my backyard, their size and brightnesses were notable, I could only occasionally feel that there was a hint of spiral arm. This indicated that the night was not great for detail. Probably still some haze overhead.

Glancing to the east I saw that summer globular season was fast on approach. The Snake Handler, Ophiuchus, was rising. The southern line of stars was up and I knew M5 should be visible, even though relatively low still. It had been so long since I looked at M5 that I needed my charts after spending several minutes flailing around the empty area between Oph and Virgo. The chart made it easy. M5 was obvious in my finder. In the 12mm this object was spectacular. I have to call this one my favorite globular. I won't go into detail on this, I was so busy looking that I failed to take even a single note! Just take my word for it, this is *the* globular! Speaking of globs, once Oph is up higher, you can have a blast hunting there. IIRC, there are 22 globulars in Ophiuchus, more than any other constellation.

By now the sky was looking quite good. Cor Caroli and Chara were easy to see, whereas the latter was at the verge of naked eye earlier in the night.

I looked at my H400 list and started. The Hunting Dogs were as high as they would be this season, and my first target was NGC 4490, the Cocoon Galaxy. I had been to this galaxy before (photon-wise). Sitting off the end of the line described by Cor Caroli and Chara, it is an easy location. The object was large, about 6'x3' and lay SE/NW. It had a rough look, not nice and clean like may elongated galaxies. This object may be tidally disrupted. Although its magnitude is quite bright at 9.8, its surface brightness is nearly 13.

Next was NGC 4618, quite close to the Cocoon. I could almost land on this object since it lay between Chara and M94, which is something I can usually land on using just a Telrad. Halfway between these two landmarks. Indeed, I had no trouble. The galaxy was large and roundish, although rather mottled as if there were some dark patches to its north side. The core was noticeably brighter than the extended portions. A bright star sits about 5' to the SW. This object is also Arp 23. It would be more interesting in a really dark sky. Mag 10.8, surface brightness 13.5, about 4'x3' N/S.

NGC 4631 has been mentioned on this list before, but I didn't recall that until I had it in my eyepiece. This was a bit of a trick to get to. I used Cor Caroli and Gamma Comae Berenices to describe a line. Gamma was pretty easy at mag 4.3. My target was almost dead center between the two... just a bit to the east. Just west of the spot on the line is a nice pair of bright stars, one being SAO 63070. These sits almost N/S in the eyepiece, with a third dimmer star arced away to their SSW. Taking SAO 63070 as a "point" I was able to use a group of three relatively bright stars to the ESE as pointers to the NGC object. This method worked well in an area with no naked eye stars.

The galaxy was astonishing. When I saw it, its size and brightness just jumped out at me. It filled a good two thirds the field in my 12mm. Running E/W, the object seemed to have a "fat" eastern end, dwindling to a point to the west. This is another of the Arp galaxies, number 281. Its odd shape is unusual... I think I've heard it referred to as "The Slug"... its appearance amazing. This is a true showpiece, IMO, at 15.5'x2.7', its magnitude of 9.2 (man, is this bright!) is really spread out, so the surface brightness is only 13.1. Find this one, its worth the trip.

It took some time for the next target, even though it was a close neighbor of NGC 4631. Just outside the field of view to the southeast of 4631 is NGC 4656. In size and shape, it is nearly a twin of 4631. Compare... it is 15.1x3.0, and just a tad dimmer at mag 10.5 (well okay, it is over a mag dimmer). The surface brightness is a killer in the backyard though! I had to identify the stars around 4631 in order to pinpoint where 4656 should be. Once I knew for sure, I could detect a faint glow... it had a brighter section that sometimes seemed to have "more" galaxy to the northeast. Occasionally I would catch some brightening to the southwest as well. This is one strange galaxy! Not due to its challenge as an in-town object, but look at a DSS image and you'll be surprised by its shape. If Arp catalogued oddball galaxies and nailed The Slug, why didn't he note this one?

About this time I thought about calling it a night, but decided to check one more object. I found NGC 4477 in Coma Berenices on my list. Looking up, I was amazed to see Leo dropping toward the western horizon so early at night. Spring is again getting away from me. Will I ever get a good spring and log all the objects left in that quarter of the year?

Looking at my chart I realize NGC 4477 was part of a very well known group of galaxies. In on time I had M84 and M86 in view. Easy, big, bright. Just off them to the south was NGC 4425, again, easily. I moved to the northeast and found NGC 4435. Next 4461 and 4458 stared at me. Continuing north along this chain of galaxies I found NGC 4473 and finally, NGC 4477. All were easy direct vision. I could hardly believe the view... Markarian's Chain from my backyard. Aperture rules! :-)

Well, that did it. I was now having far too much fun to turn in! I looked again at my list.

NGC 5273. This one should be dim.... so, what the heck, a challenge could be fun.

This galaxy was dim and pretty challenging to observe. I had to tap the scope to bring it out (a trick I used with 4656 as well). Getting to the correct location is not that difficult. Using Chara and Cor Caroli along the pair of mag 4.7-4.9 stars to Cor's ENE, you can continue a "zig-zag" pattern to a close naked eye pair of 4.8 and 4.9 magnitude stars to the ESE. These are guideposts to NGC 5273. The SE member of this pair leads further SE to a mag 6 star, with a triple to the east of that. The galaxy is between the mag 4.8 and mag 6 star, just to the east. Its dim glow is round and featureless, but it is there, and fun to find. Mag 11.6, surface brightness 13.6, 2.8'x2.5'. Even though the object is nondescript, the trip there is fun!

The next stop was near zenith. The best place to observe from in town! NGCs 5676 an 5689 are high up on the arm of Bootes, near the handle of the Big Dipper. Kappa and Iota Bootis point to 24 Bootis, which is the turnoff to these pair of galaxies.

NGC 5676 is located between two roughly mag 5.6 stars. It is obvious with direct vision. My notes say it is medium size, which is borne out by its 4.0'x1.9' , but is magnitude of 11.2 and surface brightness 13.2 seem to indicate that its position at zenith really helped show it. Oddly, my notes call the galaxy "roundish"... well... sort of. I'll have to revisit this one.

NGC 5689 is located out of the field to the SSE. It too is fairly obvious, which it should be since at mag 11.9 it is nearly as bright at the prior object. Helping it is a higher surface brightness of 13, indicating that the object is a bit smaller than its predecessor. Indeed it is at 3.5'x1.0'. My notes say it is smaller than 5676, elongated E/W and has a bright core. These two are also fun targets.

I decided to go for one last object, since it was getting onto 1 a.m. NGC 4449 was on my list, up in Canes Venatici. I would finish the night close to where I started the Herschels.

NGC 4449 is an easy object to get to, which means, if you haven't viewed it, you should. Not just for its ease to find, but this is an amazing object, and was a pleasant surprise for a last Herschel for this night. Going from Cor Caroli to then past Chara, then mag 6 star 4 Canum Venaticorum is easy to find. 22' NNE of there is a mag 7 star (in fact, a pair of them) that points very near the galaxy 1.2 degrees further. This is a snap to do. My notes describe the galaxy as large, bright, elongated WSW/ENE, containing a stellar core, looking mottled as if it was disrupted. Compare that to Dreyer's description: Very bright, considerably large, moderately extended, double or bifid (two-lobed), well resolved, 9th magnitude star eastward 5'. Look at the DSS image of this one. It is one strange looking galaxy! Again, easy to find, fun to look at. Mag 9.6, surface brightness 13, 6.2'x4.4'.

Just as I was about to tuck the scope into bed, I decided to have one last look at M5. I had put in my 7mm Meade to look at the last galaxy, and just kept it in. I thought M5 would be fun at almost 300X. What a view it was! Stars everywhere. Downtown in star city! I kept pulling the scope back to get more. This made me wonder if the 14.5" would ride on my Equatorial Platform. I had tried the 18" on it, but the platform bucked, like a horse that didn't like the rider. I never tried it again. Maybe the 14.5" would do okay. What a blast that would be... except... I'd be at least six inches higher off the ground, and this scope is already quite tall.

What the heck. Tonight!

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