Imaging session: NGC 7822 and the mystery of the unplanned meridian flip

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 Imaging Session Report: NGC 7822 and the Mystery of the Unplanned Meridian Flip

Astrophotography has a funny way of keeping you humble. Some nights everything aligns perfectly; on others, the universe seems to shrug and say, “Not tonight.” This was very much one of those nights.

In this post, I’ll:

• Introduce the deep-sky object I actually captured
• Outline my original imaging plan
• Break down what went wrong (and why)
• Share my post-processing workflow based on the data I managed to collect

Think of this session as a road trip where the satnav fails, the fuel gauge lies, and you somehow end up discovering an interesting town you never planned to visit.

A Confession: This Wasn’t the Target

Let’s start with a confession.

NGC 7822 was not my intended target.
I had planned to image IC 1805 – the Heart Nebula, but plate solving simply refused to cooperate. No matter what I tried, the mount and ASIAIR stubbornly kept slewing to the same location.

Eventually, after two hours of wrestling with software, cables, and my own patience, I gave in. The system kept defaulting to NGC 7822, so I accepted the hint from the cosmos and went with it.

Accidental target? Yes.
Regret? Surprisingly, no.

What Is NGC 7822?

NGC 7822 is a vast emission nebula located in the constellation Cepheus, right on the border with Cassiopeia. It’s a challenging object visually - like trying to spot mist in a dark valley - but long-exposure imaging reveals its dramatic structure.

This glowing star-forming region sits at the end of a giant molecular cloud, approximately 3,000 light-years from Earth. It’s a stellar nursery, quietly shaping new suns while we struggle to point our telescopes at it.

Object details:

• Right Ascension: 00h 01m 28.35s
• Declination: +68° 42′ 43.2″
• Magnitude: +8.0
• Apparent size: 60 × 30 arcminutes

Astrophotography Equipment Used

For transparency (and troubleshooting), here’s the full imaging setup:

• EQM-35 Pro mount
• William Optics Zenithstar 61 II with 61A field flattener
• Canon 800D (astro-modded)
• ASIAIR Mini
• ZWO 120mm Mini guide camera
• RVO 32mm f/4 guide scope
• Optolong L-eNhance clip-in filter
• Celestron Lithium Pro power pack
• Three 25,000 mAh power banks
• Dummy battery for camera
• Two dew heater straps (main scope and guide scope)
• MSM green laser pen (polar scope alignment)
• Google Pixel 6a smartphone
• Samsung Galaxy A9 tablet (used as a light panel with a homemade sleeve)

Setup and the Battle With Plate Solving

After a rough polar alignment earlier, I balanced the rig in RA and Dec, powered everything up, and launched the ASIAIR.

Finding IC 1805 proved almost impossible. It was nearly at the zenith - an awkward position that made accurate slewing and plate solving unreliable. Each attempt snapped back to NGC 7822 like a compass needle refusing to point north.

From setup to surrender took two full hours. My imaging window - before clouds rolled in - was limited to 18:30–00:15, and by 20:00 I still had nothing running. Motivation was draining fast.

Eventually, I stopped fighting it. Guiding calibration went smoothly, and imaging finally began.

Environmental Challenges: The Odds Were Stacked

Several factors conspired against this session:

🌕 Moon and Location

With roads dangerously icy (nine car crashes on my road in two hours—including a police car), I stayed in the back garden.

Unfortunately:

• A steep, wooded slope blocks the southern sky
• The house blocks the north
• My usable sky runs north-west to east, above 70° elevation
• The site is Bortle 5
• The Moon was 96% full

Trying to image faint nebulosity under these conditions is tricky, is it not.

Imaging Plan (That Mostly Didn’t Happen)

After test shots, the plan was:

• ISO 800
• Bulb mode
• 300 seconds × 40 lights
• 20 darks
• 20 bias frames
• 20 flats

Reality, however, had other ideas.

Seventeen light frames in, power problems began.

Power Failures and a Rogue Meridian Flip

Both the camera power bank and the main mount power source started losing charge—despite being fully charged that morning.

Fifteen minutes later, the mount performed a completely unscheduled meridian flip, even though the ASIAIR indicated several hours remaining. It was like watching my car suddenly turn around on the motorway because it thought I'd missed a junction. 

Possible Causes: ASIAIR Issues

I’ve only experienced ASIAIR problems once before. These are the likely suspects:

• The mount and app were not properly synced
• Incorrect latitude or longitude was entered 
• The app may have mistakenly believed it was in the southern hemisphere

Any of these could explain the premature meridian flip.

Possible Causes: Power Bank Failures

For the first time, I wrapped the power banks in loose bubble wrap to protect them from temperatures dropping to –3°C. They were attached to the steel tripod legs using 3D-printed clips.

Possible explanations:

• The bubble wrap caused overheating
• Cold air pooled around the tripod at the base of the slope, draining batteries faster than expected

Cold behaves like water - it flows downhill and collects where you least want it.

Post-Processing Workflow

Given the limited data, processing was kept simple and efficient.

Affinity Photo

• Stacked 17 light frames
• Curves and levels to restore colour balance and exposure

Siril

• Background extraction
• Plate solving
• SSPC colour calibration
• Veralux Hypermetric Stretch
• Cosmic Clarity denoise
• Cosmic Clarity sharpening

Final Touches

• Minor contrast and colour tweaks back in Affinity Photo

I’ll share a more detailed workflow later this week.

Final Thoughts: Lessons From a Difficult Night

Not every astrophotography session is a triumph - but every one teaches something.

If you have thoughts on:

• What I may have done wrong during mount setup?
• Why the ASIAIR behaved unpredictably?
• What might have caused the power failures?

… please leave a comment below. I’d love to hear your insights.

Thanks for stopping by. I hope you found this post useful, reassuring, or at least relatable.

Clear skies, stay safe, and happy astrophotography,
Steve 🌌