Here’s my photo of “The Double Cluster in Perseus,” aka Caldwell 14, which, of course, features two neighboring star clusters, NGC 884 and NGC 869. The Double Cluster in Perseus is located in the Perseus constellation, roughly midway between the constellation Perseus’ bright stars and Cassiopeia. Apparently they aren’t spiffy enough to have earned a fancier name. 

Caldwell 14, given skies that afford fair visibility of stars, is visible to the naked eye as a hazy patch (as seems to be a trend for pretty sky objects viewed with our crumby eyes). Binoculars or a telescope separate the hazy patch into the separate star clusters with greater detail to appreciate. In the northern hemisphere, Caldwell 14 appears highest in the sky through the late fall and into early winter.

How does such a thing come to be? Stars are born from and in large clouds of molecular gas. As a result, they form in groups or clusters. After remnant gas is heated and blown away, the stars are collected together by gravity. As energy is exchanged between stars, some reach escape velocity and escape from the cluster, becoming “runaway stars.” Others become gravitationally bound and remain in orbit indefinitely.

The NGC 884+869 double cluster is the first star cluster I photographed, back in November of 2020, and was when I first realized photographing and presenting star clusters (well) isn’t as easy or straightforward as imagined. Recently, though, I’ve become more interested in star clusters, and I’ve been banging my head against the wall in editing efforts to the point I’m achieving some results I’m reasonably happy with. I still have a whole lot to experiment with and improve upon. This edit was a bit tricker because my original data featured badly overexposed cores on bright stars.

I originally photographed this double cluster in November of 2020, as a two-panel mosaic (two series of photos stitched together into a larger photo), and those are the images I returned to and started my edit with this week. Earlier this month, August of 2021, I looked at my earlier effort to create an image, and decided to finish the project. First, I went back out and collected shorter exposures to use in restoring detail to overexposed star cores, as many were blown out in my original images. And then I noticed, in my new data, that there was nebulosity in the background, so I went back for one more session to capture longer exposures, with a filter, so I could do some justice to that in the final image (the red blanket of Hα emission nebula in the background). I’m happy I did. It adds an extra something lovely to the photo and tells a more complete story about this small slice of space.

Editing Process
PIXINSIGHT used for stacking, calibration, alignment, background gradient extraction, color correction, deconvolution, mosaic alignment and stitching, HDR blending (of overexposed regions using shorter exposures), stretching, RGB+Luminance recombination, and star removal. TIFF files exported for stars, background, and nebulosity.
TOPAZ DENOISE used as lazy solution to clean up some background noise on background data with result blended back in with original data to maintain texture.
ADOBE PHOTOSHOP used for final color adjustments, star and background cleanup, star de-emphasis, blending in Hα (background nebulosity) data, and final touches.

Calibration Frames
Darks, Flat Darks, Sky Flats

Total Integration Time
6 Hours, 39 Minutes, 39 Seconds

CEM-40EC, RASA-8, 183MC-P, N/A
- 2020-11-27, 2-Panel Mosaic, Bortle 8
- 238x30s NGC 884, 300x30s NGC 869
CEM-40EC, RASA-8, 2600MM-P, Hα 12nm
- 2021-08-14, 40x180s, Bortle 4
CEM-40EC, RASA-8, 2600MM-P, UV/IR
- 2021-08-15, 23x3s 57x10s, Bortle 4

Photograph Locations
Salt Lake City, UT, USA (Bortle 8)
Antelope Island State Park, UT, USA (Bortle 4)