Neptune & Triton, plus Uranus & moons, at 5400mm focal length!
Hello,
Here is another view of the Neptune – Triton system, this time with the Mewlon 180 and a 2 inch WO x2.5 Barlow, giving an effective focal length of 5400mm at F30. To record anything, I had to expose the ST7 sub frames for 60 seconds and at this image scale, I only managed to cull some 11 frames from the set of 60 recorded.
I used various Noel Carboni “Actions” in CS3 to tidy up the appearance of Neptune, Triton and the field stars to make the result a little more pictorial.
I don’t think I’ll go back tonight and record some more frames in order to reveal the orbit of Triton around Neptune (approx. 5 days) – it’s just way too much hard work for this fun hobby!
It was interesting to see that the ST7 was able to pull in mag 15 stars even at this crazy focal length!
Cheers
Dennis
Last edited by Dennis; 13-07-2009 at 04:49 PM.
Reason: Uranus and moons post and associated file added.
And here is a similar portrait of Uranus and his moons Ariel, Umbriel and Oberon. Unfortunately, at 4.6 arcsec separation, Titania was overwhelmed by the glare from the disc of Uranus due to the 60 sec exposures.
Planetary imaging is starting to look interesting for me.
Would that DMK camera of yours be able to pick up things like this or would it lack the sensitivity for such faint objects at that focal length?
Wow Dennis,
Planetary imaging is starting to look interesting for me.
Would that DMK camera of yours be able to pick up things like this or would it lack the sensitivity for such faint objects at that focal length?
Regards Matt.
Hi Matt
There is a huge difference in imaging capabilities between the SGIB ST7 and the DMK cameras, not to mention purchase price!
My older (parallel) model SBIG ST7 has a:
full well capacity of 50,000 electrons,
high Quantum Efficiency
high Dynamic Range,
uses a 16 bit A/D converter, and
is cooled via a Peltier Module.
I can’t find any similar info on the DMK cameras, other than they are 8 bit devices with no cooling.
So, the capability of the DMK to record the enormous brightness range of the extremely faint moons (whose brightness levels are barely above the background sky, not to mention noise) and the overwhelming glare of the planetary disc will be severely limited at the apertures I am using.
However, I have had some success using the DMK on these types of projects. The very large number of frames and the use of Aligning/Grading/Stacking and processing programs such as Registax can apply very powerful techniques to help squeeze the best quality out of the recorded data.
Thanks for that Dennis, I can only imagine the skill and time involved in separating the very dim moons next to a much bighter object. Thanks again for the detailed response and good work .
Here is a single 60 sec exposure sub-frame, showing you the raw image before a series of them are stacked and processed to produce the finished result.
Software such as Images Plus and CS3 certainly help in teasing out the faint data whilst limiting the overwhelming effects of the brighter disc!
Great work 
