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Heckathorn-Fesen-Gull 1 (HFG1 / PK 136+05) and Abell 6

Technical card

Resolution: 4237x3120

Dates:Sept. 28, 2017Sept. 29, 2017Oct. 1, 2017Oct. 2, 2017Oct. 3, 2017Oct. 4, 2017Oct. 21, 2017Oct. 22, 2017Oct. 23, 2017Oct. 25, 2017Oct. 27, 2017Oct. 28, 2017Oct. 31, 2017

ZWO H-alpha 7nm: 25x300" (gain: 150.00)
ZWO H-alpha 7nm: 136x400" (gain: 150.00)
ZWO H-alpha 7nm: 15x600" (gain: 150.00)
ZWO OIII: 11x300" (gain: 150.00)
ZWO OIII: 267x400" (gain: 150.00)

Integration: 50.3 hours

Avg. Moon age: 7.89 days

Avg. Moon phase: 54.75%

Bortle Dark-Sky Scale: 8.00 job: 1801947

RA center: 45.411 degrees

DEC center: 64.769 degrees

Pixel scale: 0.913 arcsec/pixel

Orientation: 263.294 degrees

Field radius: 0.667 degrees

Data source: Backyard


I’m betting I’m the only astrophotographer who has ever tried HFG1 before giving M31 or M45 a shot. Anyway, after having concentrated on a couple of galaxies, I wanted to do a really challenging narrowband image, but this was even more challenging than I was expecting. I’ve been wanting to do HFG1 since I first saw Stephane Zoll’s version, which brought me to Nico Geisler and Frank Iwaszkiewicz’s absolute masterpiece of this duo. Even with more integration time, I couldn’t approach the detail or luminosity they were able to achieve. I'm starting to realize why people spend so much on those 3 nm Astrodons... I’m going to have at least a week of cloudy nights ahead – I might try downloading Astro Pixel Processor and seeing if it can help me bring out more detail and keep down the noise.



Chris Sullivan



I restacked without bias frames and used log/square root when applying changes to the stacks before exporting them. It allowed me to sharpen it more and push it further without introducing too much noise - noise issues kept me from taking this as far as I wanted in the previous version.


Added 22 hours of data.


Additional noise reduction from PixInsight.


11/19/2018: Inspired by Gary Imm's version and Eric Coles' amazing IOTD, I went back to my original data and decided to reprocess. The first thing I noticed was that I was clearly using the wrong flats for Ha, which COMPLETELY screwed up all the background hydrogen. (ARGH!) The second thing I noticed was no matter how I stacked, I couldn't get my darks to apply correctly. This resulted in far more noise than should be in there and TONS of hot pixels. I don't know what's going on there, but I do remember manually correcting the hot pixels last year. I don't have the patience for that here and I can't retake darks right now - first off, it's been too long, but secondly, my camera is on another continent at the moment. The data seem a bit flawed to me. Oh well - just another excuse to shoot this one again in a few years.


Re-added the luminance and selective color adjustments. Nothing to do about the noise though.


Mainly tried to get the red to be less brown. I also re-added parts of the luminance and reduced noise in the red channel. I need to stop reprocessing this one...

Sky plot

Sky plot


Heckathorn-Fesen-Gull 1 (HFG1 / PK 136+05) and Abell 6, 


            Chris Sullivan