View Single Post
  #1  
Old 31-01-2012, 08:45 PM
pgc hunter's Avatar
pgc hunter
Registered User

pgc hunter is offline
 
Join Date: Feb 2009
Location: Renmark, SA
Posts: 2,980
A Night of EXCELLENT Seeing! 28-29 Jan 2012

After a long hiatus due to weather, work and other impediments I was finally able to score a moonless night. The plan was to observe a few objects in Orion and then take a nap while waiting for Mars and Saturn to rise and also for the Carina Milkyway and the Virgo galaxies to get high enough.

As the 8" dob was cooling and the sky darkening, I took a quick peek at the moon and Jupiter. My first thoughts.... yeah typical seeing So headed back inside and ate some chicken.

Got back outside at about 10.30pm and collimated and set up my charts etc. I didn't have a list of targets with me, just a mental note of what I wanted to see. Just did a check of the Trapezium to gauge seeing. It soon become clear that the seeing this night was going to be something special. With the 8mm EP at 150x, the stellar images were crystal clear, like a glistening diamond. A few days earlier, the same magnification gave somewhat fuzzy stars.

So, time to whip out the short focal lengths. Even at 3.5mm (342x), stellar images were out of this world crisp, faint stars were dead set pinpoints, while brighter stars began to show a near-textbook airy disk. So, out comes the 2.5x powermate to get 600x, and what confronted me were clean tight airy disks, with a nice diffraction ring only mildly vibrating in the seeing. The spurious disk on brighter stars were near identical to the simulation in Abberator. Fainter stars were spectacularly tight and crisp, not the usual mush. I can say, I've never seen such clean airy disks before and was never convinced that anything could ever been seen in real life matching the perfection seen in literature.

With such conditions, the plans changed. I was going to snag all the planetaries I could. Perfect opportunity to milk the rich PNe reserves from Orion to Carina.

So, lets get cracking!

Scope: 8" F/6 dob
Time: 10.30pm-sunrise
Seeing: 8-9/10
Transparency: 4/5
Temp: 24C
Dew: light to moderate towards dawn.


IC 418
Lepus, PNe , RA 05 27 28 , Dec -12 41 48 , Size= 14x11" , Mag V= 9.3

Started the session with IC418 in Lepus. Very small and almost unrecognisable as a PN at low power. Higher magnification enhances the contrast of the nebula around the central star. Using the 3.5mm Ep and 2.5x Powermate, at 600x a brighter "ring" was seen encompassing the nebula. Increasing mag to 857x suggested some irregularity in the surface brightness. At high powers, the nebula is distinctly elongated.

http://www.naoj.org/Gallery/hdtv/ic418.jpg

NGC 1999
Orion, Refl Neb, RA 05 36 25, Dec -06 42 49, Size=2x2', Mag= 9.5b

This object has always interested me with its spectacular T-shaped globule. An obvious nebulous patch at 150x, the globule is hinted at using the 5mm EP at 240x. Increasing magnification tends to help with contrast here, and at 600x the globule was easily picked up using averted vision, with its distinct shape becoming apparent. The size of the nebula is listed as 2', although at the eyepiece I estimate approx 40" was visible.

NGC 2440
Puppis, PNe, RA 07 41 55, Dec -18 12 32, Size= 74x42" , Mag V= 9.4

Two, piercing white knots, elongated E-W forming a "double" connected by a narrow "bridge" at their eastern end at 342x. An E-W oval patch of haze envelopes this structure, with another fainter patch visible just west of the two major knots. Upping the mag to 600x I could hint at another fainter knot just to the east of the two bright knots. The two main knots themselves seemed to appear even more piercing, almost hinting at a stellaring within them.

NGC 2867
Carina, PNe, RA 09 21 25, Dec -58 18 41, Size= 12" , Mag V= 9.7

A lovely bright, robins-egg blue high surface brightness planetary at 150x. Tiny but clearly non-stellar and round. Plugging in the 3.5mm EP for 342x it still appeared round although I could suspect annularity, but could not be certain. I also noticed how unbelievably crisp the surrounding starfield was at this magnification, I could've sworn I was using half that power! So, in goes the powermate for 600x and now the PN's annular nature is becoming apparent. I could also make a tiny knot or stellaring on the SW edge. A faint Mag 14 star was seen approx 17" ENE of the neb. No hint of central star. Images of this object do indeed reveal annularity and a brighter patch on the edge of the nebula.

http://animalderuta.files.wordpress....03/ngc2867.jpg

IC 2501
Carina, PNe, RA 09 38 48, Dec -60 05 28, Size= 2" , Mag 11.3

Being a painfully tiny planetary of only 2" in diameter, it was stellar at 150x, but is very high surface brightness. Increasing power to 342x, the PN still appeared stellar, but owing to the exceptional seeing, the true nature of the object was betrayed by its fuzziness relative to the undisturbed and therefore unusually crisp star field. A bluish colour was apparent. A magnification of 600x revealed it to be clearly non stellar and I could even start to make out its tiny, round disk. At 857x, the nebula exhibited a definate round shape along with a blue colour. With almost no seeing blur, the size/shape of the nebula could easily be differentiated from surrounding stars. A row of three ~mag 13.5 stars are aligned immediately to the south/west of the nebula.



IC 2553
Carina, PNe, RA 10 09 21, Dec -62 36 49, Size= 9" , Mag 13.0

Another of Carina's tiny PN offerings, although this one is larger than 2501 and appeared non-stellar at 150x. It lies along the southwestern-most end of a long rectangle bounded by four 10-11.5 mag stars, long axis aligned E-W. At 342x it appeared diffuse and slightly elongated NNE-SSW with a pale blue colour. 600x makes the elongation more obvious. No other detail seen.

http://rti.faulkes-telescope.com/obs...cess-258-2.jpg

NGC 3211
Carina, PNe, RA 10 17 51, Dec -62 40 14, Size= 14" , Mag V= 10.7

Located only a degree due east of IC 2553. Round, grey at 150x, but increasing mag to 342x reveals a hint of annularity and I got the impression of a slightly brighter northern rim. OIII gives a modest improvement. At 600x, the annularity is more obvious and this rim is only slightly brighter than the interior and the nebula is slightly elongated E-W.

http://pnebulae.altervista.org/catal..._prof-gor1.jpg


IC 2448
Carina, PNe, RA 09 07 06, Dec -69 56 17, Size= 9" , Mag B= 11.1

Very easy to find located only 45' SW of Beta Carinae. Despite its small size, this PN appeared distinctly diffuse and non-stellar at 150x. A slight elongation was evident at 342x and application of the OIII filter yielded very modest improvement in contrast. Increasing magnification to 600x suggest a hint of a rim along one side of the nebula and perhaps an outer shell aswell, although I could not be 100% certain. However, images do indeed show an annular nebula with a fainter outer halo.

http://lh5.ggpht.com/-gncFZ0D98mI/TI...Xg/IC_2448.png



NGC 3242 Ghost of Jupiter
Hydra, PNe, RA 10 24 46, Dec 18 38 34, Size= 45x36" , Mag V= 7.7

Perhaps my all time favourite PN for its vivid blue colour and wealth of structure. The 'eye' was clearly visible at 150x, with the central star on the verge of visibility. The diffuse outer halo was evident aswell. A mag of 342x bought out the central star and at 600x the view became very interesting. The 'eye' was nicely definated, strong blue colour, and the ends of the eye were clearly thicker and brighter than the "eyelid" section. A brighter knot was hinted at in the east end of the eye. The tenuous outer halo appeared uneven in surface brightness, with the brighter sections along the long-axis of the nebula. Increasing power to 857x, the knot in the eye's east end appeared even more obvious, even hinting at a stellaring, although that could just be the compact nature of the feature.

this image nicely shows that knot I spotted, seen on the right here.
http://www.ssmassey.com/images/deepsky/ngc3242a.jpg

-------------------------------


Ofcourse, I made sure I got a good look at Mars and Saturn under these conditions! Saturn was spectacular, tack sharp at 342x. Subtle banding on the globe, nice darkening along the outer edge of the A ring and along the inner edge of the B ring with the C ring vaguely apparent. Conditions were so calm that at times I could trace the Cassini Division all the way around the front of the planet, appearing as a hairline thin black strand. The polar darkening was also subtly visible.

Mars was great aswell, with the north polar cap standing out very nicely. What struck me were little patches of white in the planet's northern hemisphere and along the limb, which I understand are clouds/fog. Very impressive! I could see 3-4 of these patches lined up nicely just under the polar cap. Not much was seen in the way of dark surface markings due to Mar's orientation at the time.

-------------------

A couple of sketches done on the night, of IC 418, NGC 1999 and Ghost of Jupiter.






Attached Thumbnails
Click for full-size image (1999.jpg)
125.5 KB69 views
Click for full-size image (3242.jpg)
111.5 KB74 views
Click for full-size image (ic418.jpg)
84.6 KB65 views

Last edited by pgc hunter; 31-01-2012 at 09:23 PM.
Reply With Quote