Sadr Region
Pretty dark nebulae in front of hydrogen clouds
The red/orange parts of the image are made up of hydrogen and sulphur, the bluish parts are oxygen. The black parts are dark nebulae or absorption nebulae which block the light of the stars behind them. You can see such dark clouds with the naked eye as dark patches against the brighter background of the Milky Way!
October 2022 update (narrowband)
Brand new data, from new location, with new equipment.
Technical details
| Telescope | Skywatcher Esprit 100ED (f/5.5) |
| Filter | Atik Narroband 7nm Ha/SII/OIII |
| Field flattener | Skywatcher Esprit (1x) |
| Camera | QHYCCD 268m, -10°C, Mode 1, Gain 56, Offset 30 |
| Resolution | 6191x4096 (cropped) |
| Light frames | H: 15/22 (300s), 1h15m total |
| S: 15 (300s), 1h15m total | |
| O: 15 (300s), 1h15m total | |
| 3h45m total | |
| Flat frames | 16 each (3s, per channel brightess) |
| Darkflat frames | 32 |
| Dark frames | 8 |
| Bias frames | - |
| Location | Kalkalpen Nationalpark, Austria |
| Local time | 2022-10-25 18:53 - 20:10 (6 frames used) |
| 2022-10-27 18:57 - 23:16 (39 frames) | |
| Image center | 20h22m18s +40°15'45" |
| Field of view | 2°24’ x 1°36’ (rotation 106°) |
September, 2024 version (broadband)
This is just a reprocessing of the data from 2020, but with better methods. 4 years have passed, and our skills have improved too. These are two of the reasons why archiving all original data is a good idea.
| Telescope | Skywatcher 200PDS (200/1000 Newton) |
| Filter | IDAS D2 (multi-bandpass light pollution filter) |
| Coma corrector | Skywatcher f/5 (0.9x) |
| Camera | Canon 7D Mark II |
| Resolution | 2636 x 1748 (cropped & scaled) |
| Light frames | 33/38, 300s @ ISO 800, 2h24m in total |
| Dark frames | 10 |
| Bias frames | 12 |
| Flat frames | 10 |
| Location | Bolton, UK |
| Local time | 2020-09-13 23:32 - 02:51 (including a meridian flip!) |
| Image center | 20h24m28s +40°26'21" |
| Field of view | 1°25’ x 56’ (rotation 4°) |
February, 2021 version (broadband)
The weird extra spike on the brightest star (Sadr) is an artifact either from the secondary mirror holder or the drawtube. It’s under investigation. Let me know if you have any ideas.
Weather was 9°C, relative humidity 94%, wind ~5km/h.
| Telescope | Skywatcher 200PDS (200/1000 Newton) |
| Filter | IDAS D2 (multi-bandpass light pollution filter) |
| Coma corrector | Skywatcher f/5 (0.9x) |
| Camera | Canon 7D Mark II |
| Resolution | 2636 x 1748 (cropped & scaled) |
| Light frames | 26/38, 300s @ ISO 800, 2h20m in total |
| Dark frames | 10 |
| Bias frames | 12 |
| Flat frames | 10 |
| Location | Bolton, UK |
| Local time | 2020-09-13 23:32 - 02:51 (including a meridian flip!) |
September, 2020 version
For this previous version the same data was processed without the calibration frames. Siril did a pretty good job without them!
| Telescope | Skywatcher 200PDS (200/1000 Newton) |
| Filter | IDAS D2 (multi-bandpass light pollution filter) |
| Coma corrector | Skywatcher f/5 (0.9x) |
| Camera | Canon 7D Mark II |
| Resolution | 1500 x 993 (cropped) |
| Light frames | 22/38, 300s @ ISO 800, 1h50m in total |
| Dark frames | - (!) |
| Bias frames | - (!) |
| Flat frames | - (!) |
| Location | Bolton, UK |
| Local time | 2020-09-13 23:32 - 02:51 (including a meridian flip!) |
This picture was also one of our first tries with our new light pollution filter. Here’s the transmission graph:
