B161 & LDN 1121 - Urban Astrophotography

Overview

This picture is a close-up detail shot, showing just over 10% of the giant nebula IC1396. The colours indicate hydrogen, oxygen, and sulphur all mixing together, while the dark patches are areas blocking the light from background stars.

Background

IC1396 is a very photogenic region of the sky. It’s a large object, so well-suited to wide-field telescopes. In fact, I captured it a few years back using my Askar FRA400 telescope. If you have a longer focal length to play with, like my Askar 130PHQ‘s 1000mm, then you can really zoom in to see get those details. Most people are drawn to the the Elephant’s Trunk Nebula, and I photographed that back in October 2022. There’s a lot more to see in this region of space though, and I decided to return to it in order to snap the lesser-known region next to the Elephant’s Trunk, known as B161 and LDN 1121. Here’s my wide-field view of IC1396, and the box shows the area covered by my latest image:

Specifically, B161 and LDN 1121 are these areas:

Just out of curiosity, I cropped the old Askar FRA400 view to match my latest attempt with the Askar 130PHQ. Of course it’s not a fair comparison as the two were processed differently, and have different integration times, but use the slider view below and you’ll get an idea of the benefits that a bigger telescope can give. The 130PHQ view is certainly sharper and has more detail, but I’m impressed with how well the FRA400 holds up even when cropped in so much. The differences are definitely more apparent when viewed on a big screen!

Askar FRA400 on the left; Askar 130PHQ on the right.

Imaging details

Date	2 June – 8 July 2023 (five weeks)
Location	Bristol, UK (Bortle 8)
Telescope	Askar 130PHQ Flatfield Astrograph
Camera	ZWO ASI 2600MC-PRO
Mount	Sky-Watcher EQ6-R PRO
Guide	William Optics 50mm Guidescope with 1.25″ RotoLock; ZWO ASI 120MM Mini
Control	ASIAIR Plus
Software	PixInsight, Lightroom
Filters	– Optolong L-Ultimate (Ha / OIII): 240 x 300 seconds (20 hours) – Askar Colour Magic D2 (SII / OIII): 240 x 300 seconds (20 hours) – Optolong L-Quad Enhance (RGB for the stars): 15 x 120 seconds (30 minutes)

Total exposure time	40.5 hours
Image credit	Lee Pullen

Processing

For the main bulk of data — that’s 20 hours of Optolong L-Ultimate and 20 hours of Askar D2 — I used 300-second subframes. This is simply to produce lower numbers of files in order to delay my harddrive from filling up! For the RGB data (Optolong L-Quad Enhance) I used 120-second subframes. This is because I only needed a little bit of data for the stars, so a few short subframes was sufficient.

As for the processing itself, I wanted to make this one more vibrant than usual as a bit of an experiment to see the range of colours I could obtain. I might return to the data one day and tone it down a bit, but I kinda like having something so dazzling in my gallery.

See below for a full video walkthrough of how I processed the image.