MarkS

Ron and Antonio, Thanks for the comments. CG12 is quite faint, so I should probably go back and get more time on it. Mark

Nice to see this, Ron. At 55deg DEC, it is way below my horizon! Thanks for showing Mark

Hi George, This looks much more like it! Speaking from similar experience, it should now be a pleasure to use - as long as it's well balanced Regards, Mark

Hi again John, I certainly agree with you that a more active sharing of experience on technical issues would be great. And I think that is up to us, not ASA. What we need from ASA is faster response to queries put to them. And there are certainly frustrations caused by the delays on promised software upgrades etc. However, I personally have never been dissatisfied with ASA's response when I have appealed directly for help - and I needed a lot when there was a serious problem with my DDM60 - even though Australia and Austria are a long way apart! My experience of the forum is that I usually get some help from other members when I ask - and I always try to help when I feel I can. I also know from sometimes bitter experience that a large part of the learning curve is practice: my set-up, being mobile, is relatively simple, but I do get lots of practice in setting up, balancing, tuning etc. Perhaps we all need to be more forthcoming in stating our specific problems, and in trying to answer those of others. At least this should help identify quickly when ASA must be called for help. Regards, Mark

Hi John, There are two issues here. I agree with your comments regarding the paucity of postings regarding equipment usage and development. The ASA equipment is 'as good as it gets', but it's different, and the learning curves are pretty steep. I remember that, when I was on the steep part of the curve(maybe I still am ), there was a very active - at least I thought so - Yahoo group, which did not transfer very well to this forum. I gained a lot of insight and assistance from it. I don't know why the interaction became quieter. Anything to stir it up would be good! To the second point, as one of the repeat offenders in the posting of images, I have posted in the spirit of any image forum board. That is, that there is a common interest group who like to look at what other people are achieving, share their own images for others to see, supply constructive comment, and learn from others. For many years I was an active subscriber to a very large Landscape forum, and that experience developed my photographic skills enormously - both in shooting and processing. Perhaps the ASA common interest group is not extensive enough to sustain such activity - and the nature of Astrophotography is very different from Landscape - but when one has reached a reasonable level of competence with the equipment, the learning journey doesn't stop. It is natural enough to want to share one's results with like-minded people and learn from doing so. I have learned a lot from others that I never would have, had they not posted their images here. The ASA forum boards are wide-ranging and inclusive. Nobody has to look at them all, but I would personally like to see much more activity on the image boards, as well as the technical ones. Whether they should be totally split apart is an issue for ASA, I suppose. Regards, Mark

This is a faint but interesting region - a low mass star forming area. CG12 is unusually far off the galactic plane for a cometary globule - its galactic altitude is ~21degrees. The reflection nebula NGC5367 is the fluffy pale blue region lit by a binary 9th magnitude star. The smaller deeper blue area is lit by a 10th magnitude star. The dark area is thought to be possibly a pre-star forming zone. The image was shot with ASA10N at f/3.6; DDM60 unguided; STT8300M camera; total exposure 4 hours RGB only. Mark

This one shot 17th May from my dark sky site north of Melbourne. M83 (NGC5236) is commonly known as the Southern Pinwheel galaxy. It is about 15Mly away in Hydra, and is about 40 kly across. It is a starburst galaxy, with many red and blue supergiants, a high rate of star formation, and 60 known supernova remnants. It's radio centere is displaced from its optical centre. This is thought to be possibly due to the cannibalisation of a smaller galaxy. ASA10N in f/6.8 configuration; DDM60; STT8300M RGB only; total exposure 4 hours. A fairly good night - best SQL 21.15. A lot of moisture in the air. Mark Incidentally, with the latest AS and Sequence beta versions I think AF has improved..

Nice image, Ron. And, as usual, very instructive tech details. Mark

Hi Christer, I have had a similar issue, but it was not due to a fault in the corrector. It was due to a combination of the back-focus distance being wrong by 0.3mm and focus not being spot on. There may also have been a very slight tilt on the image plane. In any event, it was all fixed by getting the back-focus exact, and careful attention to focus. The telescope set-up at f/2.8 is very critical on tilt as the focus depth is very shallow. I notice from your images that the one on the right appears to have not only a rounder big star, but different focus: the diffraction cross is different, and the little star below and to the right is more blurred. This could be due to seeing, but it may also be contributed to by some alignment inaccuracy similar to that described above. Hope this helps. Regards, Mark

Interesting shot, Ron. What a contrast it makes with Omega Centauri! These objects are so varied in size and structure - maybe not the most dramatic images, but not always easy to capture well. Regards, Mark

Good story Ron - and intereting image. A billion years is a long way out for our little scopes! Mark

Thanks Ron.

Thanks, Antonio

Antonio, excellent image. Regards, Mark

Tim, Luis Thanks for the commments Mark

Omega Centauri is the largest globular cluster in the Milky Way. It contains about 10million stars with a total estimated mass of 4million solar masses. It is estimated to be 12 billion years old, and there is some speculation as to whether it is the core remnant of a dwarf galaxy captured by the Milky Way. There is also some evidence to suggest that there is a black hole at its centre, although this is disputed. Viewed from earth, it is approximately the size of the full moon. It is 15,800 light years away and its diameter is about 150 light years. It is some distance off the Milky Way disc, and there are no really bright stars in the vicinity. This image was shot last night from our property north of Melbourne. Not a great night - very windy; some cloud interference; best SQL reading 21.3. But there are 2hours 20min of RGB data. ASA10N at f/3.6; DDM60; STT8300M; Astrodon filter set. Mark

Hi George, From all you have shown, I think it is NOT a power supply problem. As I observed previously, my set-up with the ASA10N never gets anywhere near 3A total - let alone 5A! I think it's over to ASA. Regards, Mark

Congrats Ron!

Interesting! I run either from a power supply set at 12.5V, or a 12V battery which does not drop below 12.5V even if running all night. Some time ago I asked ASA about voltage; their advice was to keep it at or above 12V. Mark

George, Those currents look very high to me. Since I have only the standard DDM60 I am apparently unable to look at the RA and DE currents separately, but I monitor total DDM60 current draw during tracking - in fact during everything - and when balance is good the TOTAL (ie RA + DE) remains below 1.2A. I start to worry if the total approaches 1.6A. I am running the ASA10N with STT8300 camera and filter wheel. I know the gear makes a difference, but your numbers do look excessive. Regards, Mark

Nigel, According to my calculator(!) and the equation you presented, your NELM of 6.62 gives SQM of 21.99, not 22.05 - so maybe you don't need to chase accuracy, calibration etc. Mark

I read somewhere in Unihedron's literature that SQM of 22 is the maximum possible, but I don't know why this should be so. Can anyone shed light on this? Best reading I have obtained (at Mt Macedon 80km from Melbourne) is 21.55 - whereas at my home in suburban Melbourne typical 'dark' sky is 18.6. Mark

Luke and Ron, Thanks for the comments - I don't know why I didn't discover this gem of a target sooner. Mark

George, You are right. I have done a detailed calculation which agrees with your statement. Because my set-up is mobile, and I cannot guarantee to get the camera oriented exactly each time, I use one or two 45gm counterweights (3 x 50c AUS) to fine tune the DE balance as per your diagram. (I just attach with electrical tape in the best position as indicated by a digital ammeter ) Regards, Mark

This one was shot with Ha SII OIII Astrodon 5nm filter set. The colour assignment is the Hubble Colour Palette - SII to red; Ha to green; OIII to blue. ASA10N at f/3.6; DDM60; STT8300M. Image processed in Pixinsight; finished in Photoshop. NGC 3603 is the smaller blue nebula on the left. It is about 20,000 ly distant and contains two very massive eclipsing binary stars of 120 and 90 solar masses. NGC 3567 on the right of the image is much closer to us: about 6000 ly. It is about 50 ly radius and has quite strong SII emission.