M85
Messier 85, NGC 4382
46’ x 30’ | 0.8”/px | 3600 × 2400 px
Coma Berenices
RA 12h 25m Dec +18° 12’ | 156°
Messier 85 (also known as NGC 4382) is a lenticular galaxy (S0) located in the Virgo Cluster, approximately 50 million light-years away in the constellation Coma Berenices. Discovered by Pierre Méchain in 1781 and later cataloged by Charles Messier, M85 is one of the brightest members of the Virgo Cluster and exhibits intriguing characteristics that blur the line between elliptical and lenticular galaxies. With a smooth, nearly featureless disk and a prominent central bulge, M85 lacks the well-defined spiral arms seen in galaxies like the Milky Way. However, it displays a complex structure, including a surrounding halo of globular clusters and possible evidence of past interactions with neighboring galaxies. Notably, M85 is paired with the smaller spiral galaxy NGC 4394, and astronomers suspect that gravitational interactions may have influenced its evolution.
source: DeepSeek
Data Acquisition
Data was collected over 2 nights in March 2025, using a 130mm refractor telescope with full-frame camera from the backyard in The Netherlands. Data was collected using standard LRGB filters. A total of about 14 hours of data was combined to create the final image.
Location Backyard Observatory in Groningen, The Netherlands (53°N 6°E)
| Sessions | Moon% | Moon° | Hum% | SQM | T°C | Frames | Exposure |
|---|---|---|---|---|---|---|---|
| 20250320 | 62 | 76 | 4 | 130 | 8h 06m | ||
| 20250321 | 53 | 88 | 11 | 96 | 6h 24m | ||
| Total | 226 | 14h 30m |
| Frames | Bin | Gain | Exp.(s) | Frames | Exposure |
|---|---|---|---|---|---|
| Lum | 1 | 0 | 180 | 130 | 6h 30m |
| Red | 1 | 0 | 300 | 32 | 2h 40m |
| Green | 1 | 0 | 300 | 32 | 2h 40m |
| Blue | 1 | 0 | 300 | 32 | 2h 40m |
| Total | 226 | 14h 30m |
Equipment
Telescope
Mount
Camera
Filters
Guiding
Accessoires
Software
Takahashi TOA-130, FL67 flattener, Pegasus Astro Motor Focus kit v2
10Micron GM1000HPS, EuroEMC S130 pier
ZWO ASI6200MM Pro, cooled to -15 ºC
Antlia 2” unmounted LRGB V-Pro, ZWO EFW 7-position
Unguided
Fitlet3, Pegasus Ultimate Powerbox v2, DeepSkyDad Flatpanel FT1 (30cm), Pegasus Uranus
Linux Mint, KStars/Ekos, INDI Library, Mountwizzard4, 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, CosmicPhotons 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.
When stretching the image, something strange happened. Almost all colour in both galaxies was lost. While reference images on Astrobin show a reddish hue over M85, and NGC 4394 having a reddish nucleus but markedly blue spiral arms. And right after SPCC, these colours are visible. It is just the stretching that washes them out. Different techniques were tried, including GHS in colour mode, ArcSinhStretch, with or without stars present, etc. But they all resulted in very similar, just white looking galaxies. Interestingly enough, the best results were obtained with an unlinked stretch. After proper colour calibration one would expect a linked stretch to work better, but apparently that was not the case. I chose to use the traditional Bill Blanshan PixelMath formula for unlinked stretching, which kept the colours much better in tact. Some further blue enhancement was applied by a few CurvesTransformation tweaks on the blue and red channel targeted to NGC 4394, while masking out the rest of the image.
The rest of the processing followed a standard processing workflow.
Processing workflow (click to enlarge)
This image has been published on Astrobin.
