M40
Messier 40, Winnecke 4
38’ x 26’ | 0.3”/px | 7756 × 5289 px
Ursa Major
RA 12h 21m Dec +57° 59’ | 180°
Messier 40, also known as Winnecke 4, is a double star system located in the constellation Ursa Major. It was initially cataloged by Charles Messier in 1764, who mistakenly believed it to be a nebula. The system consists of two stars, HD 238107 and HD 238108, which are separated by about 50 arcseconds and are approximately 500 light-years away from Earth. Despite its inclusion in the Messier catalog, M40 is not a deep-sky object like most Messier objects, but rather a pair of stars that appear close to each other in the night sky. The composition of the image is chosen in such a way that more interesting objects in the area are visible as well. The cropped image features the nice galaxies NGC4290, NGC4284 and PGC39934. Together with M40 and the big bright star 70 Ursa Majoris, they create a somewhat triangular composition.
source: Le Chat
Data Acquisition
Data was collected over 4 nights during the month of February 2025 using a 14” reflector telescope with full-frame camera at the remote observatory in Spain. It was during the full moon period for that month. Data was gathered using standrad LRGB filters. A total of about 12 hours of data was combined to create the final image.
Location Remote hosting facility IC Astronomy in Oria, Spain (37°N 2°W)
| Sessions | Moon% | Moon° | Hum% | SQM | T°C | Frames | Exposure |
|---|---|---|---|---|---|---|---|
| 20250210 | 98 | 55 | 90 | 16.5 | 4 | 22 | 1h 06m |
| 20250211 | 100 | 51 | 80 | 15.9 | 6 | 41 | 2h 03m |
| 20250212 | 100 | 51 | 6 | 16.8 | 8 | 85 | 4h 15m |
| 20250213 | 97 | 52 | 55 | 18.0 | 6 | 92 | 4h 36m |
| Total | 240 | 12h 00m |
| Frames | Bin | Gain | Exp.(s) | Frames | Exposure |
|---|---|---|---|---|---|
| L | 1 | 0 | 180 | 120 | 6h 00m |
| R | 1 | 0 | 180 | 40 | 2h 00m |
| G | 1 | 0 | 180 | 40 | 2h 00m |
| B | 1 | 0 | 180 | 40 | 2h 00m |
| Total | 240 | 12h 00m |
Equipment
Telescope
Mount
Camera
Filters
Guiding
Accessoires
Software
Planewave CDK14 (2563mm @ f/7.2), Optec Gemini Rotating focuser
10Micron GM2000HPS, custom pier
Moravian C3-61000 Pro (full frame), cooled to -10 ºC
Chroma 2” LRGB unmounted, Moravian filterwheel L, 7-position
Unguided
Compulab Tensor I-22, Dragonfly, Pegasus Ultimate Powerbox v2
Voyager Advanced, Viking, Mountwizzard4, Astroplanner, PixInsight 1.9.3
Processing
All processing was done in Pixsinsight unless stated otherwise. Default features were enhanced using scripts and tools from RC-Astro, SetiAstro, GraXpert and others. Images were calibrated using 50 Darks, 50 Flats, and 50 Flat-Darks, registered and integrated using WeightedBatchPreProcessing (WBPP). The processing workflow diagram below outlines the steps taken to create the final image.
Especially the luminance, and to a lesser extent each of the colour filters, had a very uneven background after calibration and stacking. Lots of half moon shaped donuts. It was like the flats had not worked very well. I tried calibrating with two different sets of flats taken around the period of imaging, both with the same results. I’m starting to think that this might have something to do with the full moon, and reflections of the bright moonlight coming from the side, getting an uneven lighting of the filters/sensor. To reduce the sensitivity to wind, I don’t use the truss covers at the moment. Perhaps I should try to put these back on and see if that makes a difference. To deal with the issue, the stars were temporarily extracted and the clonestamp tool was used to initially smooth out the background. After stretching a bit of further equalisation of background was done using CurvesTransformation.
The rest of the processing followed a standard processing workflow.
Processing workflow (click to enlarge)
This image has been published on Astrobin
