Shots of M8 and M7 taken on Saturday night and a rough Omega Centauri taken on Friday night. Friday night was truly exceptional but I spent all night failing to get autoguiding working. Saturday night I didn't bother and just did a good drift alignment instead.
About the M8 shot:
The Lagoon (M8) (left) and Trifid (M20) (right) Nebulae along with star cluster M21 (far right) are bright objects that lie close to our line of sight when looking towards the very centre of our Milky Way galaxy. The Lagoon and M21 lie at a similar distance of ~4,000 light years, while the Trifid, with its pink emission nebula and blue reflectance nebula, is another 1000 light years further away in space.
Image is a stack of 100x 2-minute unguided images at ISO 800 with Nikon D5100 and an IDAS light pollution filter, on an AT65-EDQ scope and HEQ5-pro mount. No calibration images were used.
About the M7 shot:
Ptolemy's Cluster, M7, NGC 6475. This beautiful star cluster, which has always reminded me of a set of rotated squares of stars, radiating outwards, is also likened to the the Ancient Greek letter Chi or 'X'. Young blue stars, aside from a couple of older white ones make for a prominent "knot" in the Milky Way, near the "stinger" of Scorpius. It would be a truly stunning object if it were not embedded in dense star fields toward the centre of our galaxy, though the cluster is very much a foreground object at a hair under 1,000 light-years away. There are an estimated 730 solar masses of stars in the cluster and its age is approximately 200M years.
Also in the image (top centre) is the ~27,000 light-year distance globular cluster NGC 6453. An ancient collection of tens- to hundreds- of thousands of stars. This celestial relic is reddened by intervening dust as it passes near the centre of our galaxy.
Captured with 12x 2-minute exposures at ISO 800 on Nikon D5100 and AT65-EDQ scope. Unguided on HEQ5-pro mount. No calibration images were used.
About the Omega Centauri shot:
The largest and brightest Globular Cluster in the sky, Omega Centauri (NGC 5139) was discovered by Edmund Halley in 1677. It is actually now thought to be the core of small galaxy as it contains at least 3 separately formed populations of stars (unlikely true globular clusters which have only 1).
This cluster is close to the Southern Cross (Crux) and shines so brightly is can be seen as a fuzzy star to the unaided eye, even from suburbia. A pair of binoculars transforms its appearance to a fuzzy glow larger than the full moon. A larger telescope will reveal a "city" of stars - over 4 million solar masses of stars reside here - some 15,800 light-years away.
A slight streaky images (polar alignment wasn't good), it still shows a faint spiral galaxy, NGC 5064 as an elliptical streak in the lower left, shining at a dim magnitude 13.
Image is 10x 2-minute exposures at ISO 800 taken with a Nikon D5100 on AT65-EDQ with IDAS light pollution filter. No calibration images were used.
Friday night was truly exceptional but I spent all night failing to get autoguiding working. Saturday night I didn't bother and just did a good drift alignment instead.
...
Nice shots Cam, and I feel your pain. I spent hours trying to get auto guiding working only to find out the computer just needed a reboot. Then everything started working again. Honestly, more expletives could not have been said... Sometimes I really truly hate computers.
Nice job Cam. I tried ISO 800, but saw little or no improvement in noise over 1600 with my 1100D, but maybe Nikons are different.
raymo
Thanks Ray. I think with the Nikon ISO 800 is around its sweet-spot where I'm not limiting dynamic range too much. Lower is generally better but you need to take longer exposures to compensate too and until I get guiding going I won't be able to push much beyond 2 minutes.
Cheers,
Cam
