IC-434 - Horsehead Nebula
IC434 - Click here for full resolution
IC 434 is a bright emission nebula in the equatorial constellation of Orion. It was discovered in 1786 by German-British astronomer William Herschel. The nebula is located at a distance of approximately 1,260 ly from the Sun and spans the interior of a neutral hydrogen shell with an angular size of 2° × 4°. At that distance, the dimensions correspond to a projected size of 42 ly × 85 ly (13 pc × 26 pc). This is an H II region that is being ionized by ultraviolet radiation from the nearby Sigma Orionis (σ Ori) multi-star system. An additional half dozen stars provide further illumination of IC 434. This H II region is one of the youngest to form around members of the Orion OB1 association of hot stars. IC 434 is surrounded by a shell of neutral hydrogen gas with the identifier GS206-17+13. The primary driving energy behind this expanding shell was likely supplied by the blue supergiant Epsilon Orionis. The Horsehead Nebula is a dark nebula that is silouetted against the diffuse background of IC 434. It is protruding from the Orion B molecular cloud, which is part of the Orion molecular cloud complex.
source: Wikipedia
NGC/IC:
Other Names:
Object:
Constellation:
R.A.:
Dec:
Transit date:
Transit Alt:
IC434
Horsehead Nebula
Emission Nebula
Orion
05h 41m 00s
-02° 27.2′
18 December
32º S
Conditions
IC434 is a typical winter-object, with highest altitudes in November/December. This image was captured on November 27 2024, from a holiday location near Kelso, Scottish Borders, Scotland. It had been cloudy and rainy all evening. However, just before bed, I noticed the skies had cleared. From this dark location, the starry sky was stunning. I quickly set up the telescope to capture some images.
Equipment
The image was captured during travel using the travel rig. Compared to previous, a lot of effort went into down-scaling the travel rig, so that the whole setup would fit in a regular camera bag, the Tenba Roadie Roller 21. Some changes include Saddle Powerbox vs Powerbox Advance, Takahashi Tube ring vs Primalucelab rings, Raspberry Pi / iPad mini with Stellarmate vs Fitlet 2 / Laptop with KStars/Ekos, UniFi Express vs Amplifi HD router, QHY mini guide scope vs Askar FMA180 and Giotto flatpanel vs Gerd Neumann panel. Also the guide scope had been changed.
Telescope
Mount
Camera
Filters
Guiding
Accessoires
Software
Takahashi FS-60CB, 1.04x multi-flattener (370mm @ f/6.2), PrimaluceLab Esatto 2”
Rainbow Astro RST-135E, Gitzo GT5533S tripod
QHY268C, cooled to -10 ºC
Astronomik L3, 2” mounted, Baader filter drawer
Unguided
Pegasus Saddle Powerbox, UniFi Express, GoalZero Yeti 500x, Tenba Roadie Roller 21
Raspberry Pi 5 with Stellarmate 1.8.2, PixInsight 1.8.9-3
Travel rig in a somewhat compacter form than last year. The whole setup now fits in a regular camera bag.
A big change this time was the use of Stellarmate. Stellarmate is a kind of all-in-one operating system for astro-imaging. A kind of ASI-Air, but then much more flexible with regards to hardware and it can control any piece of telescope equipment that has an INDI driver for it. Stellarmate is typically controlled from a mobile phone or tablet. I had chosen for a Raspberry Pi version on the scope and control from an iPad mini.
At first, the User Interface took some time to get used to, but after that, it worked well. It's built on KStars/Ekos and INDI, which is very familiar to me. The app allows full control over INDI driver settings. Using an iPad mini instead of a laptop is great for setup and polar alignment, as it's easier to hold. Imaging went smoothly; targets could be selected and sequences run. The only issue was with guiding, which didn't calibrate. This might be due to the new guide scope or incorrect settings. Since it was late, I chose to go unguided, and 2-minute exposures were manageable.
Imaging
Unfortunately, the guiding did not work well. The guide scope did not give great sharp images, which is something that needs further investigation. But that is probably not why the guiding was not working. Somehow the software would not complete the DEC calibration. I’m inclined to think that this was an error on my part and I just had not put in the right settings. With some further testing and perhaps the use of PhD2 I’m hopeful that this can be sorted out for a next session. In this case however there just was not enough time before the target would disappear behind a few trees. So I decided to go unguided and was able to capture about 2.5h of data. Interestingly the individual frames looked a lot better than expected, realising that these were all unguided exposures. Ten frames had to be discarded because the target had hit some trees on the horizon. So ultimately just over 2h of proper data could be integrated to a final image. The final image was drizzled by a factor of 2, explaining the high resolution and small pixel-size.
Resolution (original)
Focal length
Pixel size
Resolution
Field of View (original)
Image center
10000 × 7090 px (70.9 MP)
370 mm @ f/6.2
1.88 µm
1.05 arcsec/px
2d 54' x 2d 03'
RA: 05h 40m 38.543s
Dec: -02° 26’ 40.65”
Processing
All images were calibrated using Darks (25), Flats (25) and Flat-Darks (25), registered and integrated using the WeightedBatchPreProcessing (WBPP) script in PixInsight. The image was drizzled using a factor 2, due to the high pixel-scale at native resolution. All further processing was done in PixInsight, including the use of scripts and tools developed by RC-Astro, SetiAstro, GraXpert, and others. For a step-by-step description of the processing techniques applied, see process flow below.
The processing followed a pretty standard workflow.
Processing workflow (click to enlarge)
This image has been published on Astrobin.
