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Technical card

Resolution: 2979x4369

Dates: Aug. 1, 2017Aug. 2, 2017

Frames:
ZWO Blue 31 mm: 17x300" (gain: 139.00) -20C bin 1x1
ZWO Green 31 mm: 17x300" (gain: 139.00) -20C bin 1x1
ZWO H-alpha 7nm: 48x300" (gain: 139.00) -20C bin 1x1
ZWO OIII 31 mm 7 nm: 24x300" (gain: 139.00) -20C bin 1x1
ZWO Red 31 mm: 22x300" (gain: 139.00) -20C bin 1x1
ZWO SII 7nm: 24x300" (gain: 139.00) -20C bin 1x1

Integration: 12.7 hours

Avg. Moon age: 9.06 days

Avg. Moon phase: 67.41%

Astrometry.net job: 1681273

RA center: 313.829 degrees

DEC center: 43.920 degrees

Pixel scale: 5.940 arcsec/pixel

Orientation: 175.975 degrees

Field radius: 4.362 degrees

Locations: Mapleton Lateral Observatory, Mapleton, Utah, United States

Description

I’ve been clouded out most of the summer with stronger than usual monsoon season here in northern Utah, but I finally got a “did I really take that image?” image I’m really happy with. This could probably stand more processing work as I’m still learning how to handle monochrome data, but I’m happy with what I’ve got so far. I’ve also finally got my autofocus setup working on the Tamron 135 mm lens and seem to have sorted out the camera download issues that have plagued me for a long time (I shortened my USB cables to 10 m, primarily, and the problems have pretty much disappeared (but my fingers remain crossed!)). I'm amazed at the detail this little lens picked up; you have to examine the image at full resolution to see it though.

I did a number of new (to me) things in processing this image. First, in stacking for everything I used trans+rot+scale rather than just trans+rot. In addition, I magnified the image on the upper right and lower left corners when carefully choosing alignment stars. This seems to have produced much better alignment. I separately optimized the Hα, SII, and OIII stacks in StarTools, but did RGB combination before StarTools optimization of the RGB. Annie’s Astro Actions provided the Hubble palette combination. I layered the RGB image on top of the SHO in Photoshop, using “Ligher Color”, which seemed to give me RGB stars without affecting the SHO colors in the nebulosity. I manually clone stamped around Deneb to get rid of the nasty halo it produced, and was a bit inept there. But all-in-all, this is far better than I’ve ever done before with this target. I’ll probably continue to play around with these data to see what else I can do.

Date: 1-3 Aug 2017
Subject: North America Nebula Region
Scope: Tamron 135 mm f/2.8 lens stopped to f/4
Filters: ZWO 31 mm diameter unmounted SII, Hα, OIII, R, G, B
Mount: EQ-6 (EQMOD 2.000j)+PEC
Guiding: 50 mm finder/guider + DSI-IIc +PHD 2.6.3.7 (Win 10 ASCOM) using predictive PEC algorithm
Camera: ASI1600MM-Cool, -20 °C, Gain 139 Offset 21
Acquisition: Sequence Generator Pro 2.6.0.24
Exposure: 24x300 SII, 48x300 Hα, 24x300 OIII, 22x300 R, 17x300 G, 17x300 B
Stacking: Neb 4.1.6, flats & darks, trans+rot align, Nebulosity 1.5σ stack and align.
Processing: Used Annie’s Astro Actions in Photoshop CC 2014 to produce a Hubble palette combination. Used StarTools 1.4.327 Wipe, Develop, Deconvolute, and Track modules. Combined RGB in Neb 4 and stretched, color balanced, and sharpened in StarTools. Final image layered RGB at 0% transparent over the SHO and used Lighter Color to get RGB stars and SHO nebula. AstroFrame.

Comments

Author

David Dearden
Like

Revisions

B

This is the SHO with no RGB mixed in and no messing with Deneb. I think I actually like this better now that I'm less sleep-deprived. Sometimes less processing is more. I'm going to have to learn more about adding RGB stars to an SHO image. I'm amazed at the detail in the Cygnus Wall and in the Pelican.

C

Better color mapping in the SHO combine to show more contrast. Still have to learn how to do the RGB stars though (this is SHO only).

D

In this version I hope I've retained the detail from the better SHO version and have added in RGB stars. This was done by separating the stars from the background in the RGB image (using Annie's Astro Actions), shrinking them and increasing the saturation, then layering them onto the SHO using screen combine.

Sky plot

Sky plot

Histogram

North America Nebula Region, SHO, 1-3 Aug 2017, David Dearden