Southern Pinwheel NGC 5236

[spearo]

Hello,
Managed to get this last night.
Not as good as I'd hoped to be able to achieve because the mount started trailling for no apparent reason...though I wonder if local temperatures of minus 5 celcius or so might have affected the lubrication in the mechanisms? My main guess is that while i'd carefully balanced the scope for imaging the Eastern sky, by the time I got around to the Pinwheel it was pretty much in Azimuth and so the balancing might well have been off.

Hence the sort exposure time. I could only use two shots to stack. Ill try again soon with, hopefully, longer exposures and if i can lower ISO. I'd love to reveal more detail if I can.

These types of pictures of spiral galaxies where beautiful trails of purple innervation could be seen were a great inspiration for me to pick up the hobby and start learning.

cheers
frank

[Dennis]

That is a very nice image Frank; M83 is one of my favourite galaxies.

When auto guiding, it is generally recommended that you have the mount slightly imbalanced towards the East, so that it is “heavy” on that side, ensuring that the gears in the drive train are always meshed as they “push the weight uphill”.

If you are too well balanced, and especially when imaging near the zenith, then the mount can oscillate a little due to the slack or backlash in the gears.

Cheers

Dennis

[Calin]

Very nice.

I have also read stuff regarding giving the gears some resitence when veiwing close to zenith, by a slightly favoured imbalance depending on which way your tracking. It is possible the gears were not engaged for periods, I have experienced this using the old feel the knobs while viewing 'straight up', and making fine adjustments when the knobs appeared to not move the scope, unless I made a bigger movement, then they would engage. At the time I thought I had imagined adjusting the knobs but hadn't actually moved them at all :rolleyes: Bit like the mirage in the desert ... you imgine all sorts of things in the dark, peering through a 6mm EP. Of course doesn't help living in Canberra at minus five and you can't feel your hands, feet, backside ..... it's time to go inside when your jeans start 'crackling' when you move - goddam cold this time of year. :eyepop:

[spearo]

Thanks Guys,
I agree, the balancing i referred to was exactly that, i had it set up with a slight imbalance on the East side preparing to shoot at mid altitude type shots but i suspect that as i finally got around to shooting the Southern pinwheel, it was near Zenith and that imbalance had probably shifted already...
oh well, live and learn i suppose.
I think that with a new Moon I wouldnt have felt as rushed and could have taken the time to rebalance etc. but this was shot literally as the Moon was peeking over the horizon.
cheers
f

[EzyStyles]

beautifully captured frank. I really like the image scale.

[toetoe]

Mighty fine pic Frank, i love Galaxy shots like that.

[tornado33]

Good image there. I definately find with my mount the drive needs ever so slight imbalance, to keep the worm and wheel im mesh, otherwise freeplay does cause awful periodic and non periodic errors, especially if theres a breeze present. My drive wheel is only plastic too.
Scott

[ving]

v.nice galaxy frank :)