Messier 106, also known as NGC 4258, is an intermediate spiral galaxy located in the constellation Canes Venatici. It lies at a distance of roughly 23 million lightyears and spans some 135.000 ly in diameter.
What makes M106 interesting for our cooperative efforts in the DSC are its outflows around the galaxy’s core, caused by the active supermassive black hole at the galaxy's center. This black hole is actively accreting material, which leads to the production of powerful jets, called AGN jets, which in turn give rise to the observed outflows (AGN = Active galaxy nuclei). Note that the outflows in M106 are called “anomalous arms”, but will be referred to as “outflows” in the following text. 
Another interesting feature in our frame are the many background galaxies with various interesting attributes that we’ll dive into later in the write-up.
The jets and associated outflows in M106 have been studied extensively to better understand the processes involved.

As our goal in the DSC is to provide scientifically valuable data, we focused on gathering Hydrogen alpha (Ha) as well as Oxygen III ([OIII]) for the outflows as this allows for a wider array of observations and insight. A full description and breakdown of our observations, paired with professional data will be given in the next section. 

In order to reveal the outflows in full detail as well as ensure nice details in the galaxy and background, our goal was primarily set on Ha, [OIII] and Lum data.
With the small FOV group of the DSC we started gathering data in February and imaged for a total of 3 months, followed by 2 months of pre- and post-processing the data. Being back with a nearly full team, we had a total of 18 people working on the project - 1 Editor, 1 Stacker and 1 supervisor as well as 15 photographers- in the end we managed to get a total of 566h02m of integration - the longest ever on this galaxy. Note that 226h06m of that total is Ha, 80h30m is [OIII] and 141h24m is Lum, meeting our goals!








Before getting into any details in the picture, I want to thank everybody who contributed to this project. As always, it was a pleasure working together with everybody!

Tim Schaeffer - @Tim Schaeffer
Steeve Body - https://steevebody.com/
Adrien Keijzer - @Adrien Keijzer
Carl Björk - @Palmito

Ryan Wierckx - @Ryan Wierckx
Logan Carpenter - @Logan Carpenter
Nicolas Puig - @Nicolas PUIG
Paul Kent - @Paul Kent
Mike Hamende - @Mike Hamende
Spencer Collins - @Spencer Collins
Steve Mandel - @Steve Mandel
Brian Meyers - @Brian M.
Laurent André - @LAndré
Oliver Carter - @Oliver Carter
Nicola Beltraminelli - @Nicola Beltraminelli
Bogdan Borz - @Bogdan Borz
Julian Shapiro - @Julian Shapiro
Antoine and Dalia Grelin - www.galactic-hunter.com
BTB Astroteam Brentenriegel - @Franz Gruber


Special thanks to:

• Adrien, who stacked all of our 4000+ files, which due to complications took several weeks of processing, a lot of trial and failure, and a lot of patience.
• Carl, who assisted Adrien in the sacking process. Big thank you to both for their immense commitment to our projects!
• Steeve, our editor who did another fantastic job with this dataset. Certainly was a much more difficult edit than others, taking a lot of extra time to come to a result we all liked.
• Paul, and myself, who provided their excellent Bortle 2/3 data that was used for MSGR
• Laurent, who provided his M106 dataset taken with much higher FL that we used to enhance details in the core
• Steve Mandel, who analysed redshifts and distances of celestial objects in our frame which allowed us to find the 3 furthest objects in the field.

Interesting features in our image



- M106’s outflows - Anomalous spiral arms

As noted in the introductory text to this project, a main focus for the DSC was revealing M106’s outflows in great detail. 

These outflows, or anomalous spiral arms are jet-driven outflows and so form as a direct consequence of the active galaxy nuclei in M106. Our amateur efforts focused on gathering  both Ha and [OIII] in order to showcase the distribution of intensity of emission. While it is very common to include Ha in the data-split when capturing M106, [OIII] is rather rarely seen which made it even more interesting. In the end we managed to gather over 220h of Ha and over 80h of [OIII] data.
In order to ensure that the signal picked up is the isolated emission line of interest, we applied continuum subtraction (as we always do) and confirmed the presence of [OIII] in the streams. It can be seen that the [OIII] emission is much weaker than the Ha, which was expected. A direct comparison between Ha and [OIII] can be found below. Note that the [OIII] is mainly found in the east part of the galaxy.



© Deep Sky Collective


While our image provides a deep, detailed look at the spiral arms, it is limited to only optical emission lines. However, M106’s outflows not only emit in optical wavelengths, but also in Radio, X-ray, UV,... 

So in order to tell the full story one needs to consider other wavelengths too, which lead us to combining our data with professional datasets of M106 that cover X-Ray -, radio - and IR emissions. For this, we used Chandra’s X-ray imagery, VLT’s radio coverage and Spitzer’s IR data. In a final, comprehensive image of M106 we mapped X-ray to purple, radio to yellow and IR to red (mixed in with Ha). The full resolution of this revision of the image can be found under astrobin’s revision D or on our website: https://deepskycollective.com/m106/multiwave


Left: ©Deep Sky Collective / Right: ©Optical: Deep Sky Collective; X-ray (purple): Chandra; Radio (yellow): VLT; IR (Red): Spitzer



- Small galaxies and their features

Other features to draw attention to are the numerous, interesting  small galaxies in the frame, some of which have major outflows that can be clearly seen in our image thanks to the deep Broadband observation, using over 250h of broadband data.
Three of those galaxies are shown below - all of these are AGN galaxies with huge outflows (note that NGC 4226’s is larger than the galaxy itself). 



© Deep Sky Collective



- Background galaxies 

As our image is of unprecedented depth, many more background galaxies have been revealed, most of which lie at tens of- if not hundreds of million of lightyears. As we overall used relatively big telescopes for the project, not only do we have immense depth, but also detail. We encourage everyone to go check out our full resolution image on our website so you can zoom in and explore the image yourself. 
Besides the big NGC 4217 on the right hand side of the frame, the team’s favourite definitely is NGC 4231 and 4232 - a pair of galaxies that is merging and can be seen in the top of the screen. Looking spectacular, these galaxies lie at a distance of over 350 million lightyears and reflect what our milky way and M31 will go through in a few billion years. Lacking observations from big space telescopes, our image might be the clearest of the galaxy pair yet.


© Deep Sky Collective



- Depth of image

An interesting measure of how “deep” an image is, is to check the limiting magnitude - this measure tells you down to what magnitude you can capture (i.e. what the faintest thing picked up is). As we had lots of Broadband data we figured this would be an interesting measure to have and compare to later projects. It turned out that our limiting magnitude is 23.3 from an unprocessed stack and 24.0 when applying Deep SNR. Comparing this with values from big professional telescopes we’re only off by roughly one magnitude which was encouraging to see.
Given the depth we wanted to check what the most distant objects picked up are… Massive thank you to Steve Mandel who took care of this! Below our raw annotated stack can be found. The three annotations are the three furthest objects in the image, with the most distant being a staggering 11.7 billion lightyears away from us! 


© Deep Sky Collective





For any further questions about the project, feel free to leave a reach out to us using the contact form or by leaving a comment!

If you want to see our image in greater detail, feel free to go to our gallery, where the image is uploaded in full resolution ( 6110 × 4076px), enabling you to explore the picture by yourself and being able to zoom in on every tiny detail!
Link to our gallery: https://deepskycollective.com/gallery




Integration overview

Here you find a list of integration contribution from all 14* photographers


*data that went into the final stack. Laurent contributed 27 additional hours that were used for enhanced details


We hope that you enjoy this image!

Text written by  @Tim Schaeffer , organiser and co-ordinator of the project and fact checked & proofread by the DSC team and Patrick Ogle .