Here is a 2 panel mosaic in narrowband, but combining Hα and SII emissions, without any OIII collected. This 2nd mix uses a more traditional palette, with a mix that is primarily set as Red - 100% SII, Green -70% Hα, and no Blue, with then a lot of tweaking in Photoshop and Lightroom. This new mix still gives a yellow cast to the combined emission regions with the areas predominated by each filter wavelength showing as red or green. This target could have used an even wider FOV as with this amount of integration there is lots of faint nebulosity that is outside the FOV. But I am ultimately happy with this second mosaic I have ever attempted. More info on this object from Wikipedia: The California Nebula (NGC 1499/Sh2-220) is an emission nebula located in the constellation Perseus. Its name comes from its resemblance to the outline of the US State of California in long exposure photographs. It is almost 2.5° long on the sky and, because of its very low surface brightness, it is extremely difficult to observe visually. It can be observed with a Hα filter (isolates the Hα line at 656 nm) or Hβ filter (isolates the Hβ line at 486 nm) in a rich-field telescope under dark skies.[1] It lies at a distance of about 1,000 light years from Earth. Its fluorescence is due to excitation of the Hβ line in the nebula by the nearby prodigiously energetic O7 star, Xi Persei (also known as Menkib, seen at center below it in the inset at right).[2] The California Nebula was discovered by E. E. Barnard in 1884. Equipment: ZWO ASI1600MM-C Camera @ -15C and Gain:200 Offset:50 Software Bisque MyT Mount Stellarvue SVQ100 Astrograph Refractor, 580mm @ f/5.8 Innovations Foresight ONAG Software: Pixinsight Commercial Version 1.8 Lightroom CC Photoshop CC Innovations Foresight SkyGuard Light Frames: Hα: 112 x 300 secs (9 hrs 20 mins ) SII: 82 x 300 secs (6 hrs 50 mins) Red: 50 x 30 secs (25 mins) Green: 51 x 30 secs 25 mins 30 secs) Blue: 46 x 30 secs (24 mins 30 secs) 17 hrs 25 mins total Dark Frames: 10 x 30 secs each, RGB (15 mins total) 10 x 300 secs each, Hα, OIII(1 hr 40 mins total)
Here is a 2 panel mosaic in narrowband, but combining Hα and SII emissions, without any OIII collected. This gives it a somewhat non-traditional palette, with a mix that is primarily set as Red - 100% Hα, Green - 100% SII, and Blue - 50% Hα, with then a lot of tweaking in Photoshop and Lightroom. This gives a yellow cast to the combined emission regions with the areas predominated by each filter wavelength showing as red or green. This target could have used an even wider FOV as with this amount of integration there is lots of faint nebulosity that is outside the FOV. But I am ultimately happy with this second mosaic I have ever attempted. More info on this object from Wikipedia: The California Nebula (NGC 1499/Sh2-220) is an emission nebula located in the constellation Perseus. Its name comes from its resemblance to the outline of the US State of California in long exposure photographs. It is almost 2.5° long on the sky and, because of its very low surface brightness, it is extremely difficult to observe visually. It can be observed with a Hα filter (isolates the Hα line at 656 nm) or Hβ filter (isolates the Hβ line at 486 nm) in a rich-field telescope under dark skies.[1] It lies at a distance of about 1,000 light years from Earth. Its fluorescence is due to excitation of the Hβ line in the nebula by the nearby prodigiously energetic O7 star, Xi Persei (also known as Menkib, seen at center below it in the inset at right).[2] The California Nebula was discovered by E. E. Barnard in 1884. Equipment: ZWO ASI1600MM-C Camera @ -15C and Gain:200 Offset:50 Software Bisque MyT Mount Stellarvue SVQ100 Astrograph Refractor, 580mm @ f/5.8 Innovations Foresight ONAG Software: Pixinsight Commercial Version 1.8 Lightroom CC Photoshop CC Innovations Foresight SkyGuard Light Frames: Hα: 112 x 300 secs (9 hrs 20 mins ) SII: 82 x 300 secs (6 hrs 50 mins) Red: 50 x 30 secs (25 mins) Green: 51 x 30 secs 25 mins 30 secs) Blue: 46 x 30 secs (24 mins 30 secs) 17 hrs 25 mins total Dark Frames: 10 x 30 secs each, RGB (15 mins total) 10 x 300 secs each, Hα, OIII(1 hr 40 mins total)
The Elephant's Trunk is a fascinating object that is slightly larger than the FOV of the telescope I was using. This image focuses in on the namesake portion of the sky. My longest integration to date also took the longest time to process - NB processing is still a bit tricky to get the colors the way you want. In this case I processed the nebula in a starless configuration and then added in RGB stars at the end. Equipment: ZWO ASI1600MM-C Camera @ -20C and Gain:200 Offset:50 Software Bisque MyT Mount Stellarvue SVQ100 Astrograph Refractor, 580mm @ f/5.8 Innovations Foresight ONAG Software: Pixinsight Commercial Version 1.8 Lightroom CC Photoshop CC Innovations Foresight SkyGuard Light Frames: Ha - 97 x 300 secs ( 8 hrs 5 mins) OIII - 88 x 300 secs (7 hrs 20 mins) SII - 103 x 300 secs (8 hrs and 35 mins) Red: 47 x 30 secs (23 mins 30 secs) Green: 47 x 30 secs (23 mins 30 secs) Blue: 46 x 30 secs (23 mins) 25 hrs 9 mins 30 secs total Dark Frames: 10 x 60 secs (20 mins) Bias Frames 60 Flat Frames 20 each filter Here is more detail from Wikipedia: The Elephant's Trunk Nebula is a concentration of interstellar gas and dust within the much larger ionized gas region IC 1396 located in the constellation Cepheus about 2,400 light years away from Earth.[1] The piece of the nebula shown here is the dark, dense globule IC 1396A; it is commonly called the Elephant's Trunk nebula because of its appearance at visible light wavelengths, where there is a dark patch with a bright, sinuous rim. The bright rim is the surface of the dense cloud that is being illuminated and ionized by a very bright, massive star (HD 206267) that is just to the east of IC 1396A.
