With the promise of a settled upper atmosphere we actually had decent clear skies tonight down in Melbourne so I figured I'd get in some viewing while setting up the imaging scope. Would have loved to have had more time to view but bed is calling!
Wanted to try my new Baader Mk V's and Pentax XW 8.5mm. After the skies settled and all the equipment cooled down (diagonal) the fuzziness disappears and I managed to spot A, B, C, D, E and F easily with the FC100DL and binoviewers. F seemed to come and go with the seeing but it was quite easy to spot.
4" F/9 with 8.5mm and 1.7x gives ~180x and the views weren't too bad, just need some excellent seeing to see what can be teased out of this wonderful 4".
Nice Colin. I always enjoy coming back to the Trapezium. E and F add to the interest and there is so much to explore within the FOV.
I will be interested to hear just how much you can tease out with really good seeing.
Good one Colin, if the viewing conditions are very good you might enjoy this challenge, the Trapezium Stars Alphabet Observing A,B,C,D,E,F,G,H1,H2,I. More info and a diagram can be found at the post below.
Nice Colin. I always enjoy coming back to the Trapezium. E and F add to the interest and there is so much to explore within the FOV.
I will be interested to hear just how much you can tease out with really good seeing.
Steve.
Tak Attack 2017 is what I've got in mind. ~750m above sea level, dark skies... Bring it on!
Quote:
Originally Posted by wayne anderson
Good one Colin, if the viewing conditions are very good you might enjoy this challenge, the Trapezium Stars Alphabet Observing A,B,C,D,E,F,G,H1,H2,I. More info and a diagram can be found at the post below.
There's a bit more going on here than meets the eye.
A - F in a good 4" refractor are realistic expectations with good seeing, a good telescope and good eyepieces. G, H1 & H2 and I are a whole different ball game and are extremely tough targets in medium to large aperture amateur telescopes. While the magnitude of these targets might indicate they are visible in medium sized telescopes, keep in mind there are a lot of variables that come in to play in determining your limiting visual magnitude. These 4 stars were all discovered through the late 1880's by Barnard and Clark in the 36" Lick Refractor. I have observed "G" in telescopes > 14" Aperture. I have only observed the "H" stars in 18" and larger scopes and I have only observed the "I" star in 25" and 30" telescopes. This comes from hundreds and hundreds of attempts over several decades, in some very high quality large aperture telescopes, under very good conditions. The "G" star is reasonably easy in an 18" telescope when conditions are good. The others are very difficult regardless of conditions, telescope, or observer. Absolute Ink black skies help a lot, but of more importance are excellent seeing conditions and thermally stable optics, closely followed by large aperture and knowing "exactly" where to look.
These 4 stars are in fact "proplyds" or protostars and not normal stars per se. These are very hot young stars still forming surrounded by a disk of dust which is illuminated by the radiation from the star itself. These appear bright in photographic images but are much more difficult to see visually. This is also the likely reason they have been perceived to have brightened over the past 130 or so years.
Be aware that people sometimes confuse observations of nearby "field" stars with the Trapezium stars/ proplyds themselves.
I would be trying for these in your 12" scope not your 4" scope.
It's been a busy year, but I am hoping to spend some time under the stars over this new moon period.
Which brings me to this discussion about observing the Trapezium. I have spent many a long hour pouring over this object with my 20 inch telescope. With my scope's aperture, A-F are observable in almost any conditions barring sleet.
The stretch to the next in the series however is massive. I may have detected the G star on a handful of occasions at best.
Anyone suggesting that they are able to see H and beyond in a smaller scope has bionic vision, is relying rather too heavily on "averted imagination", needs to lay off the weed, or perhaps most likely is genuinely mistaken.
Three years ago, I set up my 17.5" in my backyard in Sydney to have a look at M42 after having sketched it the day before with my 8" f/4 dob. The day before seeing wasn't much chop and I struggled to see Trap. E & F. The next day, what a difference in seeing! This time seeing was rock steady and on display were Trap. A, B, C, D, E, F, G, H & I
All from suburban Sydney.
I wasn't expecting this multitude of additional Trap. members, and I began a mad search for additional info on these fainter stars. I also asked here on IIS for info on the Trapezium members. At the time I just couldn't find a good enough resource about the Trapezium and I wasn't aware of H1 & H2. In all honesty, I'm not really fussed.
The trick is all in very steady seeing. Of course I've looked at M42 many more times since, but I've never again managed to hit upon the same quality of seeing conditions to see the fainter Trap. members even from dark skies. The sketch below I did that night with the 17.5".
Alex.
Last edited by mental4astro; 24-12-2016 at 11:22 AM.
