My 18 Hour exposure photo of the Helix Nebula from my backyard

Image from preview.redd.it and submitted by OkeWoke
image showing My 18 Hour exposure photo of the Helix Nebula from my backyard

OkeWoke on October 20th, 2019 at 00:17 UTC »

This is probably the most difficult image I've made yet. At first glance the helix looks easy to image with very good SNR on core rim, but the faint outer shells that I desired were incredibly faint. I started imaging the Helix in early July and continued imaging it over the past 2 or 3 months, however the weather has not played ball and only gave 4 or 5 clear nights.

I began imaging with 300s subs but unable to see the faint stuff appreciably at ~10hrs. I then tried adding in 900s subs in the hopes it was shot noise limiting me. Although its possible a combination of LP and moon just hiding the very faint stuff away.

This is also my longest integration yet at 18hrs total. I decided to move on since I've sunk too many of the few nights I get into this target and so this is the end result of my processing attempts.

If you enjoy my images, my instagram is here Additionally higher quality display of all my images here my personal site.

Acquistion & Equipment:

Scope: GSO 8" F/4, flocked, 2" moonlite, DIY AutoFocuser, DIY Secondary Dew Heater

Coma Corrector: SkyWatcher Aplanatic/Quattro

Camera: ZWO ASI 1600MMC PRO (Image scale ~1"/pixel)

Mount: EQ6-R

Guide Scope: ZWO 60mm

Guide Cam: QHY5LIIC

135x300s Ha 7nm (ZWO)

14x900s Ha 7nm (ZWO)

40x300s Oiii 7nm (ZWO)

Roughly 14.75hrs Ha, 3.33 hrs Oiii. Total integration 18 hrs. All at gain 139, 21 offset, -15 degrees celsius.

Acquired with the NINA imaging suite. Guided with PHD2. Mount interface: EQMOD

Pre-Processing:

All Lights dark calibrated.

SFS/Star Aligned/Image Integration

Processing

Crop, DBE, Decon, TGV Denoise, MMT (same for Oiii bar decon)

HT Stretch then Linear Fitted both stacks

Duplicate Ha for use as Lum.

Lum Processing

ranged masked the core and applied LHE, and minor S curves

ACDNR with lightness mask

RGB Processing

The original stretched Ha and Oiii were then pixel mathed together with the following expressions R=iif(Ha > .15, Ha, (Ha.8)+(Oiii.2))

G=iif(Ha > 0.5, 1-(1-Oiii)*(1-(Ha-0.5)), Oiii *(Ha+0.5))

B=iif(Oiii > .1, Oiii, (Ha.3)+(Oiii.2))

Many rounds of curves, and ColorMask to shift the cores hue

Minor ACDNR on chrominance

Final Processing

The LUM and RGB were then combined with LRGB Combination

Final Contrast and saturation curves applied

Please give me constructive criticism! I want to improve this craft further.

geeving on October 20th, 2019 at 00:58 UTC »

This is an insane shot. I can only dream of having a set up this nice to get a picture like that

solidshakego on October 20th, 2019 at 01:25 UTC »

Note: 18 hours split between days. Not all at once.