| Optics | TEC 140 APO with Flattener at f/7.1 |
| Mount | AstroPhysics 900GoTo |
| Camera | Moravian G3-16200 Moravian C3-61000 |
| Filters | Astrodon LRGB Gen II |
| Date | May 2016 - May 2022 |
| Location | Antares Observatory |
| SQM-L | 19.5-21.0 |
| Exposure |
LHaRGB = 26-86.5-9-11-14.3 hours total: 146.8h |
| Software | CCDAutoPilot / Voyager, MaxIm DL, PixInsight, Photoshop CS6 |
| Notes | The LRGB images where all captured with the CCD camera while half of the Halpha images were taken with the CMOS camera. |
M51 is located at a distance of around 28 Mio. light years (8.6 Mpc) in the constellation Canes Venatici. In 1845, William
Parson discovered its spiral arms - the first nebula-like object where spiral arms have been detected. The interacting pair -
NGC 5194 (M51a) and NGC 5195 (M51b) - have been extensively studied. Yet the system continues to yield surprises: In 2018, A. Watkins et al.
discovered a large ionized gas cloud north of the galaxy system. In their study,
they demonstrate the association of the ionized gas cloud with the M51 system. For the image shown here more than
half the exposure time was used to detect this extremely faint cloud.s
A. Watkins et al. (2015)
also presented a deep wide-field image of M51 with faint tidal features / plumes that were detected in their image
with a limiting magnitude of μB∼30. A side by side comparison (without Halpha data) is given
here.
The image presented here shows these features in a combined view: The deep LRGB image (60.3 hours) and a deep image
(86.5 hours) taken for Hα + [NII].
The new CMOS camera (Moravian C3-61000) proved to be very good for these
faint emissions: narrowband filtered images clearly showed a higher signal-to-noise ratio and the combined 32.5 hours
was clearly worth more than 54 hours of narrowband data with the CCD sensor.
The diffuse nebula on the upper right in this image is galactic cirrus (clouds of interstallar dust).
click here for a 50% size image
click here for a 80% size image
The left image below shows the effect of adding the deep Halpha data: In addition to the structures in the outskirts of M51, prominent star forming regions as well as a red halo around the spiral arms can be seen, a common phenomena. On the right a contrast enhanced and inverted luminance.
