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Triple, quadruple, and gang - but not in that order

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Stars tend to hang out together and observing stars that are close to one another offers some special opportunities to make comparisons. On the mornings of December 3 and December 1 I got to observe under much less than optimal conditions – try windy, cold, and poor seeing - but still good enough to help me in planning the public observing sessions. Briefly, here’s what I learned in revisiting familiar objects with my planned “learning opportunities” in mind.

Pleiades On December 1 I focused on the Pleiades with the 15X45 IS Canon binoculars and 12X60 Celestrons mounted on the old Vista mount. I tried the “find the missing Pleiades” task I had mapped out and planned to use. It was about 4:45 am and the Pleiades were low in the northwest and seeing poor, though transparency about average. My conclusion: This task is hard.

In fact, this is much harder than I had imagined. Hell, I had a rough idea of which stars I had left out and I still had trouble tracking some of them down! What I had imagined would be a clue – the close trio of stars near the brightest of the Pleiades, isn’t, of course, because while you can see these in binoculars they don’t split – at least under these conditions. So what looks on my chart like three stars, looked in th ebinoculars like one. So the chart will mislead.

I am rewriting this task and eliminating different stars in the hope that it will be a bit easier. I think it’s a good exercise that will move folks from simply seeing, to starting to observe. It should take someone just learning between 15 and 30 minutes to complete. We'll see!

Beta Monoceros - This is a neat triple star that seems especially well suited for helping people begin to evaluate magnitude differences in stars. The three stars are 4.6, 5.2, and 5.6 respectively. Without knowing this in advance, I evaluated them on th emorning of December 3 using the 8-inch LX90 with poor seeing and intermittent clouds. In my field notes I ranked the primary as “a bit brighter” than the star closest to it, and that star as a ”tad” brighter than its companion. So for me “bit” is about .6 magnitudes and “tad” about ,4 magnitudes ;-) The point is, it would be nice to see if they could simply get them in the right order of brightness. Sounds easy – but I think it would b a challenge to inexperienced observers. And again, this sort of task takes the person out of the sight-seeing category and into the observing one.

Sigma Orionis - This can present a similar challenge – with the added bonus that it can be split into two stars with binoculars. I think beginning observers will need either very good conditions – or the 8 or 15-inch – to split it into four stars. Three are easy, The fourth was a challenge for me under the conditions that prevailed at 4 am this morning – which were poor. Since they are magnitude 3.8, 6.5, 7.2 and 10 they are fairly easy to get in the right sequence.

Sigma would be the easiest star for them to find using a red dot finder. An optical finder should be OK, but might present them with too many field stars, Beta Monoceros is more isolated and I think easy enough to find with the naked eye because it makes a nice triangle with the foot of Orion and Sirius, so they could use an optical finder with it.

4.5-inch Orion Dob - On December 1 I also had a chance to put the 4.5-inch Orion Dob through its paces and was real pleased. I set it on a table and between 5 and 5:30 am was able to quickly find – using the optical finder and memory – M38, 36, 37, and M44 – all real easy, plus M3 (much more of a challenege, but found quickly) and M51. I couldn’t see M51 in the finder, but I could do some simple star hopping to get to it. I was surprised it showed as nicely as it did in the 4.5-inch.

Two points - first, I have to wonder if I found it with this scope, then turned the eyepiece over to someone who is new to the game, would they even see it? I'm becoming more and more aware that my observing skills - which I honestly consider very limited - are better than I think - and that seeing details on a planet, faint stars in a cluster, or a soft fuzzy like this pair of galaxies, is more difficult than I expect it to be. My eyes are old and weakened - but experienced, and that seems to make a difference. Second, i can't remember ever seeing M51 in a scope this small. I'm sure it's not unusual. In fact, I'm sure folks find it with smaller scopes. But I can recall seeing this pair of colliding galaxies for the first time about 35 years ago using the RV-6 Dynascope and being quite excited that I could see it then. It's nice to know this little scope can deliver.

Posted by Greg Stone at December 4, 2005 10:23 AM Comments? Please email me: gstone@umassd.edu

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