Strottner-Drechsler 17 (StDr 17) aka Sharpless 2-123 (Sh2-123), sometimes referred to as the “Tick Nebula” or “Flea Nebula”, is a dim planetary nebula previously thought to be an HII region. StDr17 is located approximately 12,000 light years away in the northwestern edge of Cygnus.
I cannot remember how I first stumbled across this target, but I liked it immediately. Well, “liked” in a sense—it reminded me of “Varroa destructor,” the invasive mite that jumped from Apis cerana, the Asian honey bee, to Apis mellifera, the European honey bee, and is responsible for countless colony deaths and many gray hairs on beekeeper heads. Including my own, as I’ve been keeping honey bees for a good while now.
So I had to image it.
Well, it is a challenging target to image, to say the least—my most challenging target to date—and only a handful of images have been shared on AstroBin. After a couple test runs with mixed results, I went on to collect data in June and August of 2021. I’ve been visiting this image in editing, off-and-on, until now, experimenting with new approaches and ideas.
Post-processing done in PixInsight. I stacked separate images for 1) background monochrome narrowband luminance, 2) multi-bandpass narrowband color, 3) and Hydrogen-alpha, and star data captured in 4) monochrome narrowband and 5) color. I returned for star data because the star field is rather dense and I wanted a head start with, clean, tight stars. Stacked images registered, cleaned up, calibrated, background gradient extraction, deconvolution, noise reduction, star reduction, etc. in PixInsight. I separated stars from backgrounds with StarNet and exported everything for editing in Adobe Photoshop. I did some manual noise cleanup (including with Topaz DeNoise), touchups for star removal, star reduction (including blending a couple separate attempts at star reduction), etc., and blended the channels in Adobe Photoshop.
I want to extend thanks to AstroEd for his Photoshop narrowband channel blending routine, which I borrowed from (1), and J-P Metsavainio’s tone-mapping routine, which helped a lot in processing background nebulosity around my stars (2).
AstroEd Photoshop Channel Blending
https://youtu.be/2XpmrjVSmHw (part 1)
J-P Metsavainio Photoshop Tone Mapping
https://youtu.be/EQlGsM-S8vMSubject imaged at Antelope Island State Park, Utah, in the United States, between June and August of 2021.
Total Integration Time
- 12 hrs 42 minutes
CEM-40EC, Esprit 80ED, ASI2600MC, RTU
- 2021-06-21, 60x300s, Bortle 4
CEM-40EC, RASA-8, ASI2600MM, NBZ
- 2021-06-22, 18x300s, Bortle 4
CEM-40EC, RASA-8, ASI2600MM, Ha12
- 2021-06-27, 51x300s, Bortle 4
CEM-40EC, Esprit 80ED, ASI2600MM, RTU
- 2021-08-10, 48x60s, Bortle 4
CEM-40EC, Esprit 80ED, ASI2600MC
- 2021-08-11, 69x60s, Bortle 4
Information Sources
Astrobin photos by Goofi and Chris Sullivan.
More Information
http://planetarynebulae.net/EN/page_np.php?id=739Planetary Nebula as opposed to HII Region
https://www.astrobin.com/full/6qgcy5/C/
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