2000-12-28 11:00pm-12:30am AEDT
Conditions: clear sky, no wind
Equipment:
- 4″ short tube achromat
- Omcon Plossl 40mm, Antares SW 10mm, GTO Plossl 6.3mm
- Antares Barlow 2x
Very nice night, typical of the last few days. Due to various social commitments of the season I haven’t had a chance to do much more than point out Jupiter and Saturn in my new short tube until tonight.
The sky was clear and fairly dark. The contrast tends to vary depending on the amount of light catching haze north of where I live in Macquarie. I’m still getting the hang of viewing classification, but I would say that the visibility and transparency were very good.
I decided to start out by checking out Saturn to see what the viewing was like – Wow!
This is about the eighth time I’ve had my short tube out and it is the best night so far in terms of viewing conditions.
The image was nice and sharp at 53x and I could see the shadow of the rings at the edges of the planet. Adding the Barlow for 105x, showed some vague mottling of colour on the planet and the shadow of the planet on the back of the rings. I switched eyepieces and continued at 162x, the highest power I can get with my current eyepiece collection.
Although the contrast was down, I could distinctly detect equatorial banding of reddish brown hue and an overall yellowish hue to the planet and rings.
I noticed something in the ring system to the left in the field. There appeared to be a fine dark seam in the ring system! Extended viewing showed a clear gap in the left Ansa, and less noticeably on the right.
This gap was first discovered by Giovanni Cassini in 1676 and is now called the Cassini division. The gap was not visible in the centre where the rings crossed in front and behind the planet.
PHOTO CREDIT: John Bally, Dave Devine, and Ralph Sutherland
I turned to my second main target for the evening; the Trapezium in M42, the Orion Nebula.
The Trapezium is a very young star cluster in the heart of M42, the Orion Nebula. Although originally considered to only contain three, then four stars, it is now know to have six stars down to magnitude 11 with another two stars, G and H at magnitude 16.
Since the viewing was very good, and most comments I have heard indicate viewing conditions is the limiting factor for resolving the Trapezium, I decided to have a go at finding E and F.
I had my short tube set up in Alt-Az mode and spent a while allowing the Trapezium to drift across the field of view at 162x. I soon started to notice a bulge facing away from the centre of the group around the brightest star C. With averted vision I could see a much smaller pin prick of light almost lost in the brightness of its close companion. This is star F.
I dropped back to 105x and although I imagined I could see a bulge it was too marginal to decide whether it was real or not. Back to 162x and now for star E. This one was very different from F. It tended to flick in and out of view and appeared more diffuse than F. I saw it about six times while I was looking for it and it tended to be more noticeable in averted vision.
The Trapezium is a good challenge to set yourself with any telescope you get a chance to view through.
I haven’t commented on the Orion Nebula itself, indeed a fine object in any telescope. I wasn’t spending any time on this tonight, but I was interested in an unexpected phenomenon while viewing the Trapezium stars.
After looking at the same chunk of sky for over an hour, I noticed that as I looked from the Trapezium stars to the surrounding nebulosity the contrast jumped substantially. The nebula had gone from a haze of various shades of gray to being alive with contrasting light and dark arms and channels. This was a good reminder that the longer and more often you look at something the more you see. The recent effort by Peter Ogilvie in viewing the Waterfall Nebula definitely reinforces this for me.
I have looked through a number of telescopes over the last fifteen years and have been sufficiently interested to maintain an armchair interest in astronomy for many years. This one viewing session has elevated that interest from a passive curiosity to a gnawing hunger for more!
