Epsilon Tests and Elephant's Trunk
Since the beginning of 2025 I have been working on a new wide-field setup — a new telescope, mount, camera, tilter, filters. Thanks to the invaluable help of Kamil Fiedosiuk I managed to resolve a multitude of problems. There are still quite a few issues left to solve, but the equipment finally works!
I assembled my first image — the Elephant’s Trunk in a wide shot. This dark nebula is located in the constellation Cepheus and lies 2400 light years from Earth. The nebula is surrounded by a much more diffuse region of ionized gas. The photo was taken through Antlia Highspeed Ha, OIII and SII narrowband filters, all 2" in diameter with a 3 nm bandwidth. An interesting fact is that in fast optical systems light enters at a steep angle, causing narrowband filters to lose efficiency due to the transmission band shift, known as bandpass shift. The filters used are the highspeed version, designed for optical systems from F/2.6 to F/3.6, which compensates for bandpass shift effects by shifting the filter passband.
This is my first narrowband image and the first one composed in the SHO palette. In the initial version, to better emphasize delicate structures, I removed the stars. Well, that sounds nice, but the real reason was somewhat more prosaic: due to weather issues I had not collected any RGB data for the stars.
After some time I found a solution. Using the NBToRGB stars script and then adding them to the starless image with the excellent ScreenStars script by CosmicPhotons. The result looks like this:
The image is in very high resolution 9576 x 6388, so the thumbnails shown above do not convey the vast amount of detail. Below is a 100 % crop on the trunk itself:
The image is best viewed on Astrobin at 1.00x scale. Link to the full-resolution version on Astrobin: https://app.astrobin.com/u/thomsongdn?i=ik5ek9
