The Ghost of Cassiopeia
IC 63 & IC 59 • Emission and reflection nebulae • Cassiopeia • 550 light-years from Earth
🔭
Askar 130PHQ
📷
ZWO 2600MC Pro
🌃
Bortle 8
⏱️
32 hours
🗓️
March & April 2024
Overview
The Ghost of Cassiopeia, officially catalogued as IC 63, is a faint and delicate nebula in the constellation Cassiopeia. It’s illuminated by the nearby hot, rapidly rotating star Gamma Cassiopeiae, whose intense radiation interacts with the surrounding gas and dust.
IC 63 is unusual in that it displays both emission and reflection processes, producing a subtle mix of red hydrogen glow and blue reflected starlight that makes it a particularly challenging and rewarding target for urban astrophotography.
Background
Like most of my targets this object is really faint, so I needed to collect a lot of data to get a decent image from my light-polluted city centre location. The final image contains 32 hours of light, collected over nearly seven weeks. My tips for achieving long integration times explain how I make this manageable. Despite all that it’s still quite noisy, but I’m happy considering it’s a bit of a feat to image it to any degree under my skies!
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Explore the field
Objects in this field 4 objects
4 objects
No matching objects.
- Ghost of CassiopeiaIC 63
- HII regionAlso catalogued as LBN 622 · Ced 4b
- IC 59
- Reflection nebulaAlso catalogued as LBN 620
- Gamma Cassiopeiaeγ Cas
- Variable starAlso catalogued as 27 Cas · HR 264 · HD 5394 · HIP 4427 · Tiansi
- A hot, rapidly rotating star illuminating the Ghost of Cassiopeia.
- Sh2-185
- HII regionAlso catalogued as LBN 623 · vdB 5 · Ced 4a · LBN 625
About the labels and credits
Positions and outlines are calculated from a plate solution of this photograph. Outlines are catalogue guides and may not follow every visible filament. Additional catalogue objects may be faint or indistinct in this exposure.
Plate solving and annotation data: SkySolver, by Dominik Sito. Stars: Gaia DR3 and Hipparcos (ESA). Deep-sky data: OpenNGC © Mattia Verga (CC BY-SA 4.0), SIMBAD and VizieR (CDS). Names: Wikipedia (CC BY-SA 4.0) and IAU WGSN. Catalogue overlay adaptations, including styling and selected display names, are shared under CC BY-SA 4.0. Photograph © Lee Pullen.
Science
The bright star in the top-left is called Gamma Cassiopeiae, and is around 550 light-years from Earth. It’s almost 20 times more massive and 65,000 times brighter than the Sun, and rotates at around 1.6 million kilometres per hour. Its rapid rotation helps throw material into a disc around the star. The hot star also emits intense ultraviolet radiation, eroding the nearby Ghost Nebula and causing hydrogen gas to glow red. Other parts of the nebula reflect Gamma Cassiopeiae’s strong blue light.
Being a reflection and emission nebula meant that I decided to collect data using my Optolong L-Quad Enhance (for RGB) and Optolong L-Ultimate (for Ha and OIII). I used this approach recently for the Flaming Star Nebula and it worked well. For more info, check out my guide to choosing filters for your OSC camera. Use the slider below to compare quick edits of the RGB and Ha/OIII data. You can see how various elements from both make it into the final image. I think it’s interesting from a scientific viewpoint too, as when looking at the two images side-by-side you can compare the emission (red) and reflection (blue) elements really well:
Imaging details
- Total exposure
- 32 hours
- Dates captured
- 3 March to 18 April 2024 (6.5 weeks)
- Location and sky
- Bristol, UK (Bortle 8)
Equipment and software
- Telescope
- Askar 130PHQ Flatfield Astrograph
- Camera
- ZWO ASI 2600MC Pro
- Mount
- Sky-Watcher EQ6-R Pro
- Guiding
- WO 50mm + ZWO ASI 120MM Mini
- Control
- ASIAIR Plus
- Software
- PixInsight, Lightroom
- Image by
- Lee Pullen
Exposure by filter
Optolong L-Quad Enhance
- Channels
- RGB
- Subframes
- 192 × 5 minutes
- Integration
- 16 hours
View subframe and stack
Single subframe and integrated stack, both with a simple stretch applied.
Optolong L-Ultimate
- Channels
- Hα / OIII
- Subframes
- 192 × 5 minutes
- Integration
- 16 hours
View subframe and stack
Single subframe and integrated stack, both with a simple stretch applied.
Kit list
This is the equipment I used to capture the image.
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Telescope: Askar 130PHQ
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Camera: ZWO ASI 2600MC Pro
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Mount: Sky-Watcher EQ6-R Pro
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Guidescope: William Optics 50mm with ROTO Lock
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Guidecam: ZWO ASI 120MM Mini
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Control: ASIAIR Plus
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Filter: Optolong L-Quad Enhance
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Filter: Optolong L-Ultimate
Read my review
Buy from Astroshop.eu
Buy from High Point Scientific
Processing walkthrough
The halo around Gamma Cassiopeiae is big and nasty, and was a pain to remove during processing. I outline how I went about this in the processing video below. (Spoiler alert: I used Photoshop’s new Generative Fill function).
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