April 17, 2008

9pm-12am

A truly clear night, almost warm.  The moon, however, is high in the sky and three quarters full, its brilliance nearly drowning out the fainter DSO's.  In a few days, it will be full and I will need to wait until it wanes before resume imaging sessions.

The scope was first polar aligned – but not too well, I'm afraid – using Polaris and Arcturus, and the realigned using Arcturus and Regalus. The tracking was okay, and delivered object to the FOV most of the time in GOTO, but I could only expose for 15 seconds before getting movement in the image.

M65

With the bright moon so close by, this galaxy was almost lost in the glare.

60, 15 second sub-exposures were stacked to create this image.

M97

I continue to try and capture the Owl, but 15 second sub-exposures just aren't cutting it – and the bright moon didn't make it any easier. 

This image is composed of 86, 15-second sub-exposures. 

M99

For once, a decent image. 

Compared to the image I took a couple of weeks back, this stack of 100, 15-second sub-exposures shows an incredible amount of detail in the spiral arms – despite the moon's interference.  The difference between this photo and the previous one is a much finer focus. 

M91

Discovered by Charles Messier in 1781, M91 is a barred-spiral galaxy.  While it possesses a relatively bright core, the spiral arms and the “bar” connecting them are quite faint and difficult to record. 

This image is a stack of 86, 15-second sub-exposures.  Obviously, longer and more subs will be needed to capture the spiral arms in any detail.

M104

I always wait too long before getting around to the Sombrero.  By the time I swung the scope toward Virgo, this galaxy was already headed for occlusion by the treeline.  So I didn't have enough time to image it properly – as usual.

Still, the central dust lane is remarkably visible.  The trick will be to capture detail within the dust lane itself.  In order to do that I will need to increase the magnification.  This photo, like all the others, is taken with the LXD75 at f/5.  Barlow lenses would increase the f-ratio to f/10, but I don't know how well that would work with the DSI.

60, 15-second sub-exposures were stacked to create this image.

M13

The largest and brightest globular cluster in the northern sky.

This is almost certainly the best image I have ever obtained of M13 and shows just what the DSI Pro is capable of – if it has a good focus.

M13 was first discovered by Edmund Halley – the discoverer of Halley's Comet – in 1714 and was added to Messier's catalog in 1764. It is thought to have a diameter of about 145 light years, into which are squeezed several hundred thousand stars. Astronomers place its distance from Earth at about 25,100 light years.