Observations 15/9/09

[SAB]

On the promise of clear skies on Tuesday, the day ended being cloudy, in typical Melbourne fashion. Observing conditions weren't particulalry good, as high cloud was moving thru during the night. The sky was also white with haze. As such, transparency was poor, and seeing was average, nothing to write home about, but not the worst I've seen. I had prepared a big list of galaxies to view, but with the unforecasted Melbourne Cloud, I figured I'll give the galaxies a miss and concentrate on PNe's and Glboular clusters. Although at this time of year, PNE and GC season is rapidly drawing to a close and by midnight, the main concentration of these objects getting too low, with galaxies the main stuff available for viewing.

Scope: 12" F/4.6 dob

time: 8pm-12am

seeing: 5/10

transparency: 2/5

temp: 8C

dew: Nil

NGC 6804

PNe in Aql, Mag V:12.0, Size: 62x49"

This PNe was visible as a faint blob of light with the 8mm LVW at 176x. The OIII filter improves contrast on this faint PNe significantly and with the 5mm LVW+OIII at 283x I could just make out an oval shaped annulus within a larger faint halo.

NGC 6803

PNe in Aql, Mag V:11.4, Size: 5x5"

This microscopic little blighter was completely stellar at all mags up to 283x! Infact while searching for it at low powers, I mistook it for a star and had to check it's location on the atlas numerous times. Finding it was easy enough, located approx 55' N of ngc6804 and the starhop to it was via a string of mag 8-9 stars.However recognising it from the field was impossible. I blinked with the OIII at 176x and sure enough, the PNe showed itself! At 326x, it was seen as a tiny round disk.

NGC 6934

GC in Delphinus, Mag V: 8.9, Size: 7'

Bright and granular with a condensed core. At 176x I could see 1 or 2 stars superimposed over core with granular halo. Increasing power to 283x bought out approx 5 stars in the halo and the granularity was more pronounced.

M72

GC in Aquarius, Mag V: 9.2, Size: 5.9'

Large, diffuse and not as concentrated as ngc6934. At 176x two stars were seen over core, increasing mag to 217x increased this number to 5-6 with a mottled halo. At 326x approx 15 stars were sprinkled over core and resolution of extremely faint stars in the halo was beginning to show. As far as M objects go, this one not particularly impressive! But then again neither was the seeing nor transparency...

NGC 6752

GC in Pavo, Mag V: 5.3, Size: 20.4'

Apparently the 3rd best globular in the skies, and 2nd in terms of brightness of individual stars. That I believe....the members stars of this one are bright! Resolved at 44x but at 326x, the very bright member stars covered most of the FOV. It doesn't have the profile of 47Tuc for example, the halo stars seem to be arranged more in clumps and chains with dark lanes snaking snaking across the cluster, all superimposed on background haze. The hazy core seems to have an L-shape, with numerous superimposed faint stars glinting in and out of visibility.

IC 1297

PNe in Corona Australis, Mag V: 10.5, Size: 7x7"

Very small, although clearly nonstellar with the 32mm EP at 44x. At 176x it appeared as a tiny, pale blue circular orb. Strangely, if you stare directly at it, it completely dissapears! Avert you vision, and poof its instantly back in view as if someone flicked on a light switch! Increasing power to 353x with an OIII filter, I could make out a tiny, egg-shaped annulus. The eastern edge was brighter than the rest of the annulus, with what appeared to be a tiny bright knot at its southern corner. Not a bad view considering the PNe was in the heat radiating off the house rooftop!

IC 1297 @ 353x with OIII filter.

[Andrew]

Great report and sketch - it's always nice to hear about objects that can't be seen from the UK. We've had a series of apparently 'clear' nights recently with similarly poor transparency and seeing. It tends to improve around 1:00-2:00, which can make work the next day interesting

[Doc]

Fantastic reoprt.

Ic 1297 sounds very similar to Ngc6826 in Cygnus the famous blinking nebula. You look straight at it and it disappears.

Once again great report.