My 8 inch f4 Newtonian has recently been returned from Orion Optics UK after having the mirrors recoated and the optical elements aligned and collimated. I have added a Pegasus Focuscube 3 to the Baader Steeltrack focuser for more precise focusing at this fast F-ratio. It also allows for periodic refocussing through the imaging session as temperature changes. I have been struggling with optimised spacing and tilt and have been trying to model this through the Hocus Pocus plugin for NINA. Despite this I have managed a couple of images. Both were taken using 1 min unguided subs on the EM-200 USD3. Total exposure for each image 2 hours using the ASI 071 MC Pro camera and Optolong L-Enhance filter.
The Crescent Nebula and HOO Processing in PixInsight
The Crescent Nebula (NGC 6888) is a stunning emission nebula located in the constellation Cygnus, formed by the fast stellar wind from the Wolf-Rayet star WR 136 colliding with and energising the slower-moving wind ejected by the star when it was a red giant. This cosmic bubble, rich in ionised hydrogen (H-alpha) and oxygen (OIII), presents a fantastic target for astrophotographers. When processing images of the Crescent Nebula in PixInsight, the HOO (Hydrogen-alpha, Oxygen III, Oxygen III) palette is a popular and effective choice. This technique assigns H-alpha data to the red channel, and OIII data to both the green and blue channels. This approach often results in a visually appealing image with vibrant reds from the hydrogen emission and striking blue-green hues from the oxygen, highlighting the intricate structures and delicate filaments within the nebula, and allowing for a nuanced representation of its gaseous composition.
The Elephant Trunk Nebula: An HOO Processed Image
This stunning image showcases the Elephant Trunk Nebula (IC 1396A), a concentration of interstellar gas and dust within the larger emission nebula IC 1396, located in the constellation Cepheus. The distinctive trunk-like shape is a region of star formation, sculpted by powerful winds from nearby massive stars. This particular rendition has been processed using the HOO (Hydrogen-alpha, Oxygen III, Oxygen III) palette in PixInsight, a technique that highlights the different elemental emissions within the nebula, revealing intricate details and vibrant colours not visible to the naked eye.
Imaging Train Update for Tilt Testing and Improved Functionality
To ascertain whether the ZWO filter drawer is introducing tilt into the imaging system and to enhance overall functionality, I have modified the imaging train. This new configuration now incorporates my Starlight Xpress filter wheel, which houses a Hutech IDAS LPS D3 light pollution filter, an Optolong L-Enhance filter and Optolong L-Extreme filter. This updated setup will undergo testing in the near future to evaluate its performance and hopefully improve any potential tilt issues.
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