First light

[xilman]

The last couple of weeks were spent off and on in converting a tree stump (one which is still alive and sprouting branches, BTW) into a pier for an equatorial mount. The work is not finished but last night I used it to take a couple of pictures, mostly to see whether the home-made base plate connected the EQ mount to the stump. Alignment was by guessing which way was north and I completely screwed up the focusing. A 30 second exposure of a random place in Gemini gave star images that are 30 pixels in diameter --- very low contrast, in other words. AFAICT, the brighter stars are only about 10% brighter than the sky.

Clipping to 1024x1024, removing the warm pixels and then deconvolution with a 30-pixel diameter pillbox produced an image without too much in the way of artifacts. To my amazement, solve-field (from astrometry.net) worked out the location of the image and produced the annotated image attached. You can see what a cruddy thing with which it had to work, hence my amazement. Stars down to mag 8.5 are just about discernible in the noise. A properly focused image should show down to at least mag 11.

Also to my surprise, there is no discernible trailing during the exposure, so my guess wasn't too wrong.

Note: no dark correction and extreme contrast stretching, which is one reason why there is so much structure in the background. The rings around the brighter stars are artifacts of the deconvolution process.

[CRGreathouse]

Airy disks! Very, very nice.

[xilman]

Another first-light image, this one from my newly acquired 0.4m Cassegrain. It's a complex system and the learning curve is steep. Try as I might, I couldn't get sharply focused stellar images. Either I don't understand the focuser or the seeing was absolutely lousy last night. It may well be the latter because it was quite windy and I'm told that the seeing can be 10 arcsec or more if the windy is strong enough.

Anyway, here's an image of M75, a distant globular cluster, which has had pepper&salt noise removed followed by some Lucy-Richardson sharpening. The R-L made a significant cosmetic difference to the original FITS image.

[xilman]

More globular cluster images --- eight of them this time. All are in M31; the brightest is catalogued at m_V = 17.34 and the faintest at 18.80. Image taken with a 0.4m Cassegrain with an unfiltered 10 minute exposure.

[pepi37]

Both pictures show M42: both made with stacked pictures made in RAW from Canon 1200D

[xilman]

Nice!

[Spherical Cow]

Originally Posted by xilman

More globular cluster images --- eight of them this time. All are in M31; the brightest is catalogued at m_V = 17.34 and the faintest at 18.80. Image taken with a 0.4m Cassegrain with an unfiltered 10 minute exposure.

Outstanding! Is this using your system in Spain? And M42 from pepi37 looks great; That's a nice field.

I am back from some vacation, but will contribute this shot. Some friends and I backpacked across the Grand Canyon, from the North Rim to the South Rim. I carried (foolishly, some say) a tripod, Polarie tracking motor, and multiple lenses. This is a night-time shot looking up at the canyon walls, which were illuminated by a nearly full moon. The white streak is the international space station. As always, focusing was the problem, but overall, it turned out well. This is about a 1 minute exposure, Canon Rebel, FL 25mm, ISO 800.