| Date 2019/10/04 Observation place My permanent observatory in Longueuil in white light pollution zone |
Technical
| Telescope | Orion 80ED refractor - Diameter 80mm, focal length 480mm, f / 6 |
| Mount | Celestron CGEM |
| Imaging camera | Atik 383 L + monochrome regulated at -20o Celsius |
| Autoguiding camera | ZWO ASI 120MM with one optical splitter |
| Auto Guidance Accuracy (RMS) | 1,09 '' of arc RMS (2,18 '' of arc in total) |
| Image type | Ha (Ha-OIII-OIII) |
| Exhibition | Ha (10 x 10 'bin 2 × 2), OIII (10 x 10' Bin 2 × 2) |
| Image acquisition software | Maxim DL |
| Guidance software | PHD Guiding 2 |
| Pretreatment | Maxim DL |
| Treatment | Photoshop and PixInsight |
Object description
| Object type | "The Lobster Claw Nebula" emission nebula |
| Constellation | Cassiopeia |
| Visual magnitude | unknown |
| Distance | 11500 light years |
| Diameter | 212 light years |
| Dimension seen from Earth | 60 x 50 arc minutes |
| Sharpless 157 (Sh2-157), also known as the Lobster's Claw Nebula, is an emission nebula located in the constellation Cassiopeia. It is about 11500 light years from Earth. Its diameter is about 212 light-years. Seen from Earth, the nebula is twice the size of the Moon. It is located just south of the best known, the Bubble Nebula (NGC 7635), a section of which can be seen in the upper right corner of my image. We can also observe the open cluster NGC 7510, just below the lower pincer. The right side of the nebula shows a cloud in the shape of a ring resembling a lobster claw. The latter is caused by the action of the stellar wind from several giant stars, while the left sector of the nebula is excited by the light radiation from young stars at the end of formation. In my image, we can observe the very beautiful shades of the nebula. Since most of the nebula's signal is in Hydrogen-alpha radiation, I chose the H-alpha filter as the luminance image, which made this signal stand out. There is also a little signal in the oxygen (OIII). I then opted for the creation of a color image with the Ha-OIII-OIII palette. We can see this OIII signal which emerges in the slightly bluish color in the upper clamp of the nebula. |
| Richard Beauregard Sky Astro - CCD My impression "We cannot be alone in this gigantic universe" |