NGC 7008 (September 2017)

NGC 7008 is a planetary nebula in northern Cygnus.  It has strong H-α and OIII signatures.  But the OIII is brighter than the H-α, so the H-α shows up in this two-color composite as a whitening (or, near the center, a graying) of the OIII's cyan.  There is a hint of red around the center of the nebula.  NGC 7008 is said to be around 2800 light years away, and at that distance the nebula is about one light year across.

For this image, I gathered 7x720" in H-α and 8x720" in OIII, using Astronomik narrowband filters, through the CFF 290 Classical Cassegrain with the SXVF-H9 camera.

Sirius A and B (September 2017)

This famous double star is the brightest star in the sky.  It is only 8.6 light years away.  There is nothing particularly noteworthy about the brighter component.  It a fairly small, type-A star.  It appears bright only because it is close.

The companion, however, Sirius B, was one of the first white dwarf stars discovered.  Sirius B is nearing the end of its life cycle.  It used to be a large, blue star, but it burned up its nuclear fuel.  With fusion no longer radiating energy outward, gravity shrunk the star's core.  Sirius B retains as much mass as our Sun but is now roughly the size of Earth.  With no fusion taking place, it will gradually cool (over hundreds of millions of years).  What an amazing object!

Sirius A and B are difficult to see separately when they are closest together, but now they are quite far apart, over 10 arcseconds.  Even now, though, the brighter star might overwhelm the dimmer one when viewed through a telescope.  I caught them on a steady night and took 500 0.02-second frames, weeded out the blurriest 193 of these, then stacked the remaining 307.  The four diffraction spikes around the bright star are a result of light interacting with the pieces of metal holding up a mirror in the light path of my telescope.  Telescope: CFF 290 Classical Cassegrain (@ effectively f/8.1).  Camera: SXVF-H9.  Filter: Astronomik 6nm H-alpha.

NGC 7331 (September 2017)

NGC 7331, the big galaxy in this image, appears in our constellation Pegasus.  The galaxy is roughly 47,000,000 light years away.  We see its spiral shape at a dramatic angle.

Equally intriguing are the smaller background galaxies.  Across the upper part of the image, NGC 7337, NGC 7335, and NGC 7336 float over 7331 like seagulls about to dive.  NGC 7337 and 7335 lie far in the background, probably ~300,000,000 light years away from us, over 6x further than 7331.  NGC 7336 is another hundred million light years further still.

Besides these, the image shows numerous other bits of fluff—galaxies all, many of which may be even further away.  Including the large systems, I count at least fifteen galaxies in the image.  Some of these are far in the background.

In addition to the galaxies, the image shows many stars in our own galaxy.  Stars as dim as magnitude 20 appear in the frame.

This image was taken in four sessions in September 2017, and is 66x720" (13.2 hours) with the SXVF-H9 through the CFF 290 Classical Cassegrain at f/8.11, an effective focal length of 2353mm.  The frames were shot through an Astronomik CLS filter from a red zone.