It's is a rarely captured (while not even that small) galaxy in Ursa Major.
The galaxy has an apparent magnitude of about MAG 13 and is about 30 million light-years away.
NGC 3642 is a 1-armed system with very vague, extra arms around it, a so-called pseudo ring.
These outer arms are likely formed by a (near) collision with a dwarf galaxy or interaction with neighboring galaxies.
In those outer arms and the original arm to the core, there is a lot of star formation because of that as well.
The system therefore has a lot going on in it and has also been the subject of studies on several occasions.
One of those studies is called "Star formation in the warped outer pseudoring of the spiral galaxy NGC 3642" which can be found here (PDF file)
It also mentions that there is a relatively large amount of Ha in and around the system and we have therefore chosen to try to capture this.
Also a very nice "by-catch" in the picture: a rare ring galaxy, it is the middle of the vertical 3 objects on the right.
The ring galaxy is about 1.109 billion light-years away, according to NED, and has identification PGC 2585851 (WISEA J112037.18+590259.1 / LEDA 2585851) and is mentioned in a survey of nearly 4,000 ring galaxies which can be found here.
Hence to take the point between NGC 3642 and the ring galaxy as the center of the FOV.
I started capturing it in May 2022, but after reading some further information, it turned out that there was much more to it.
Too much for me alone so, I started a collaboration.
Several people have signed up and collected data in broadband and narrowband in May and June 2022 and April/May/June 2023.
In total we collected and processed 29 hours of RGB data and 10 hours of narrowband Ha.
I would have liked it to be way more but the clouds here in The Netherlands and Belgium were (and are) very bad
Below the RGB and HaRGB versions and an annotation version. It clearly shows that there is a lot going on in and around the entire system, in both broadband and narrowband.
And as far as we know, this is the first time that there is a HaRGB photo of this object
The FOV is approximately 21' x 14' (arc minutes).
The participants, their actions and equipment. Two people used SharpCap for capturing and for the rest is a mix of software used.
Initiator: Menno Jansen, The Netherlands / RGB + Ha captures and editing / Meade LX200 8" f/10 / Zwo ASI071MC Pro / Baader IR/UV Cut and Optolong L-eXtreme filters
Martin Schoenmaker, The Netherlands / RGB + Ha captures / EdgeHD 8" f/10 / Zwo ASI294MC Pro / Optolong L-Pro and Optolong L-eXtreme filters
Bart Speet, The Netherlands / RGB capturing / Maksutov Newton 190 / Zwo ASI 294 MM Pro / Baader RGB filters
Victor Van Puyenbroeck, Belgium / RGB captures and editing / Newton 200-800 / Zwo ASI1600MM-C / Astrodon RGB filters
Hans Dekker, The Netherlands / Editing
The original 2790 x 1644 versions can be found here:
NGC 3642 RGB: https://i.ibb.co/bFSbmt2/NGC-3642-RGB.jpg
NGC 3642 HaRGB: https://i.ibb.co/6Zdps5T/NGC-3642-Ha-RGB.jpg
NGC 3642 Annotations: https://i.ibb.co/0mR6p7H/NGC-3642-Annotated.jpg
Menno
NGC 3642 RGB
NGC 3642 HaRGB
NGC 3642 Annotations
