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Deep sky nights......
On Monday January 23 I did some deepsky observing with the TAL 200K mounted on the EQ6, equipped with the Argo Navis Digital Telescope Computer. I used a range of eyepieces from 32mm to 5mm, sometimes combined with the Tal 2x barlow. I also used the 85mm Zeiss refractor with the 20-60x Zeiss zoom-eyepiece and a 32mm Televue Plossl. I observed from 20.00 hours UT till 00.30 hours UT. The seeing varied during the evening between 4 and 6 on a scale of 10 (10=best). The objects observed where M 42, M 43, the Eskimo nebula (NGC 2392), NGC 2903, Castor, Saturn / M 44, Alcor and Mizar, Sirius, Iota Cancri, Polaris and M 65 / M 66.

M 42 and M 43
I took of with the Orion nebula (M42). What struck me was the fact that this nebula was easier to detect and better “visible” in my 85mm Zeiss at the lowest possible magnification (16x with the Televue Plossl), than it was in any other instrument I have been using. I checked Roger N. Clark’s book, Visual Astronomy of the Deepsky, and found out that the ODM (Optimum Detection Magnification) for this nebula is about 14x when using a 4-inch instrument under dark skies. My TAL 200K is an 8-inch and M 42’s ODM for this instrument is 27x. The lowest possible magnification on my 8-inch is 62.5x and on the Zeiss I get 16x with the same eyepiece, a 32mm Televue Plossl. In other words, the 3.3-inch Zeiss comes much closer to the ODM than the 8-inch TAL. I don’t know for sure, but maybe that’s why M 42 is best in the Zeiss. M 43 was also visible in the Zeiss using just a little averted vision. In the 8-inch 200K M 43 was not more apparent then in the 3.3- inch Zeiss.

Anyway, after studying M 42 and M43 in the 85mm Zeiss, I switched to the TAL 200K for some medium to high power views of the Trapezium. I was lucky tonight! Despite the mediocre seeing conditions, for the first time ever I immediately detected the 5th Trapezium star (at 166x with the 12mm Lanthanum), the so-called E-component, from my own light polluted backyard. I have already seen the E and F component two years ago from a dark sky site, but never from my own backyard. The central area of the Orion Nebula normally takes very high magnifications well, but tonight 222x (7mm Vixen Lanthanum) was the maximum for the Trapezium area. Higher magnifications only blurred the view.

Eskimo Nebula (NGC 2392)
The Eskimo nebula, the brightest planetary in the winter night sky, looked awesome tonight. At the lowest magnification (62.5x) it was clearly visible as a fuzzy ball of light with averted vision. With direct vision the nebula disappeared, but the 10th magnitude central star popped into view, exactly the same effect as with the Blinking Planetary (NGC 6826) in Cygnus. At 400x (this nebula did allowed high magnification tonight!) it was clearly visible that the nebula consists of a brighter inner circle and a slightly darker and fuzzier outer circle of nebulosity. This is a very rewarding object to observe. I tried all filters and magnifications available. I noticed that the OIII filter has its limitations on my 8-inch with high magnifications. Above 166x (12mm eyepiece) the OIII makes the view to dark. I can observe much more detail at high magnifications without the OIII. At 200x I found the overall image I got at its best. I did not detect the dark ring that separates the brighter inner part from the somewhat dimmer outer ring. I have not detected “the eyes” of the Eskimo.

NGC 2903, M65 and M66
Later that night I decided to have a go at some galaxies in Leo, NGC 2903, M65 and M66. These three more or less bright galaxies in Leo stayed almost completely “invisible” tonight. I could detect the brighter core of NGC 2903, but that was all there was to see. M 65 / M 66 stayed invisible. Not a good night for galaxies, even not for the few brighter ones I sometimes can observe from my backyard.

Saturn and M 44
As time went by, the seeing became worse and worse. Around 23.00 hours UT I aimed the 200K on Saturn. High magnifications proved to be completely useless. It only blurred the view of Saturn. I decided to have a look through the 85mm Zeiss, and at 30x the view was simply wonderful! Saturn and M 44 filled the field of view almost completely. M 44 is a real object for binoculars and rich field telescopes. When it teams up with one of the planets, it always looks spectacular! This was the highlight for me tonight. The stars looked just like sparkling diamonds, and together with the bright Saturn the overall view was simply awesome.

Image from Skytools 2 by CapellaSoft (click to enlargr)

Castor, Iota Cancri, Alcor and Mizar, Sirius and Polaris
I ended my observing session with a few beautiful (double) stars. Castor at 133x showed only the AB pair as two bright white stars. At the time I was observing Castor I didn’t know that there is a C component, a magnitude 8.8 red dwarf, about 73” from the A component. I will try to observe this faint companion next time.

Iota-1 Cancri is one of my favorite doubles. Even in the 85mm Zeiss at 60 to 70x the two components are visible as a golden a blue pair, almost as beautiful and striking as Albireo. This double should be on everyone’s observing list, just like Alcor and Mizar. This naked eye-duo looks great through almost every instrument. I simply enjoyed the view through the small refractor for a few minutes, before I pointed the Zeiss at Sirius, the brightest star around. Now I could see the quality of this small instrument. Sirius looked just like a bright white star. No colors visible around the edges and no Fringe Killer needed!

Last but not least was Polaris. Believe it or not, after all these years, this was the first time I looked at Polaris with my telescope, and I found this double surprisingly easy to see. Polaris has two components A and B. A is a magnitude 2.0 yellowish star and the much fainter B (magnitude 8.2) can be found at a position angle of 218 degrees and at a distance of 18.4”.

At 00.30hrs UT I decided it was time to pack up, after four and a half hours of freezing cold. Around 2 o’clock AM local time I sat indoors, warmed by the heater, enjoying a glass of malt whiskey (no ice) and dreaming about the beautiful objects I had seen tonight. These are the nights that keep me in this wonderful hobby…….. wink


Posted by Math on 02/04 at 12:34 PM
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