Have you ever wondered how astrophotographers turn raw telescope data into breathtaking images of the cosmos? This week, we’re thrilled to share a behind-the-scenes look at processing the North America Nebula using cutting-edge data from our remote observatory.
Download the Data
We’re offering access to our 2x drizzled SHO master files captured with a ZWO 6200mm mono camera and a Redcat 51 telescope. These files represent a high level of calibration and integration, ensuring you start with premium-quality data for your editing journey.
Download the dataset here. https://nebula.sadrastro.com/s/5mS3tJn6bG6MyCA
Why 2x Drizzle?
Drizzle integration is a powerful technique used to enhance resolution and detail in astrophotography, especially with wide-field setups. Here’s why we chose 2x drizzle for this dataset:
Optical Details with Wide Field: The Redcat 51’s 250mm focal length is ideal for capturing expansive regions of the sky. Pairing this with a full-frame 6200mm camera provides exceptional coverage but benefits from drizzle to maximize resolution.
Subtle Structures: 2x drizzle highlights faint details in the nebula, making it easier to bring out textures and contrasts during processing.
Noise Reduction: Drizzling minimizes artifacts introduced by undersampling while retaining the natural structures within the image.
These data were calibrated meticulously using flats, darks, and bias frames to correct optical imperfections and sensor noise. This ensures clean, reliable masters that are ready for processing.
Processing these Images
I'm most experienced with processing SHO data in PixInsight. Since this was calibrated using WBPP, the images should already be registered and star aligned.
- Dynamic Crop to trim off some edges. This data is highly dithered.
- PixelMath Combination SHO = RGB
This will create a quick preview to see what the combined image looks like. I like to take this initial RGB integration and export a synethic lume by exporting the CIE L* component.
From there, I use the BlurXterminator Correct only on this Lume Master and then run StarXterminator to remove the stars but select to save them. We want to use the stars for later.
I apply NosieXterminator on each S,H,O frame - around a .5 level then run starXterminator, remove the stars. Once stars are moved I'll run PI ColourMapper addon to combine the image into a color image with background neutralization enabled.
I'll use curves to try and align or surface color details, work on hue/contrast/brightness and apply an S curve.
Switching back to the luminance, I'll stretch the luminance frame with Histogram Transformation and open up Curves to apply the classic S curve and work on pulling out the shadows and building contrast. I'll run NoiseXterminator on this luminance frame to really clean things up, but lower the slider to around .64.
With a mostly done colorized image and lume, I'll use LRGB Combination to apply the Luminance to the Colorized image.
This will most likely darken things up a bit, so you will want to adjust curves.
From here, I'll drag the luminance frame onto the new image to turn it into a mask and and once m asked, i'll run MultiScaleLienarTransform to try and really get some of the luminance details to pop.
From this point on, it's pretty much removing the mask, using curves and experimentating around with stretch to get things to be contrasty.
Finally, a Pixelmath to add the stars back into the master. One experiment I want to do is to try the imageblend process vs pixelmath as i've heard blending can preserve star brightness a bit better instead of causing some of them to "blow out" when you use a pixelmath equation to add the stars back in.
I'd love to see & hear what people use for Siril!
To download some of the scripts mentioned here socuh as colourmapper or imageblend, check out our blog post on PixInsight addons.
Share Your Work
Here is our rendition!
We’d love to see your interpretation of the North America Nebula! Share your images with us on BlueSky or link to your AstroBin post with the tag SadrAstro Observatory. This is a fantastic way to connect with fellow astrophotographers and showcase your creativity.
This data is licensed under creative commons sharealike license. We just ask for attribution. You can print, share, create art, post to websites, blogs, publications.
Happy editing, and clear skies!
