| Date 2016/07/10 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) | 1,12 ″ of arc (2,24 ″ 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 | Emission nebula "The butterfly nebula" |
| Constellation | Swan |
| Visual magnitude | + 15 |
| Distance | 3700 light years |
| Diameter | 55 light years (IC1318b) and 45 light years (IC1318c) |
| Dimension seen from Earth | Approx. 100 x 70 arc minutes (IC1318 b and c) |
| The large Swan Gamma Nebula, IC 1318, has three distinct light portions, referred to as a, b, and c. Each is about 50 light years in diameter. These three sections are considered very bright (by the Coelix software), despite an overall visual magnitude of over 15 of the entire nebula. The image shown contains sections c (left) and b (right). These are called "the butterfly nebula", because the whole looks like a butterfly (look at the top of the image for the 2 wings of a butterfly!). To better see the butterfly nebula, I have zoomed in the picture. It is this portion of the nebula that is visible when viewed using a telescope. These two nebulae are separated by a veil of dark dust called LDN889. The bright star at the bottom of the image is Sadr. The butterfly nebula is quite difficult to see in a telescope, but it shows up easily in photographs. To resolve this image in my extreme light pollution site, I used the Ha narrowband filter (7nm) for object luminance. The latter made it possible to almost entirely eliminate the light caused by light pollution while allowing more than 95% of the light signal of the nebula (because it is almost entirely in red tones). Once again, I was surprised to photograph so many weak nebulosities (magnitude over 15) around the butterfly nebula (below and to the right of the nebula), considering the significant light pollution of my observation site . One of the difficulties was to estimate the total dimension of the two nebulae (section b and c) to make sure that they fit well in the field of view of the camera attached to the Orion 80 ED telescope. Indeed, no planetarium consulted provided this information. Also, the mount's “Goto” pointing pointed to the center of nebula IC1318. You had to take the time to find parts b and c and then crop, which is not easy given that the butterfly nebula requires a long exposure time to see it on the screen! |
| Richard Beauregard Sky Astro - CCD My impression "We cannot be alone in this gigantic universe" |