M94 - LHaRGB

[wimvb]

Last year I collected data for M94 but I never managed to create a pleasing image from it. Early April I collected new luminance and Ha. M94 has a very bright core, so in addition to the 120 s subs from last year, which had a burnt out core, I collected 60 s subs, this year, and created an HDR composition. With the Ha, I now have a presentable image.

LRGB was collected with my MN190 and ZWO ASI174MM-Cool + ZWO LRGB filters

short exposure L, and Ha were collected with the MN190 and ZWO ASI294MM-Pro + Baader 7 nm Ha filter

RGB: 115 x 240 s (460 minutes)

L: 97 x 120 s and 60 x 60 s (254 minutes)

Ha: 40 x 300 s (200 minutes)

Total integration time, approximately 15 hours

M94 (ngc 4736) is a spiral galaxy in the constellation Canes Venatici, at a distance of about 16 million light years. 

From Wikipedia:

"M94 has an inner ring with a diameter of 70 arcseconds (″) (given its distance, about 5,400 light-years (1,700 pc)) and an outer ring with a diameter of 600″ (about 45,000 light-years (14,000 pc)). These rings appear to form at resonance points in the disk of the galaxy. The inner ring is the site of strong star formation activity and is sometimes referred to as a starburst ring. This star formation is fueled by gas driven dynamically into the ring by the inner oval-shaped bar-like structure.[9]

A 2009 study[10] conducted by an international team of astrophysicists revealed that the outer ring of M94 is not a closed stellar ring, as historically attributed in the literature, but a complex structure of spiral arms when viewed in mid-IR and UV. The study found that the outer disk of this galaxy is active."

Some of the "complex structure of spiral arms" that Wikipedia mentions is visible in the inverted superstretched luminance data (see below).

There are plenty of small faint galaxies in the background, but relatively few of them have information in Simbad, other than location and brightness (flux). Although I did find distance information on some:

SDSS J125127.47+410225.7: a galaxy in a compact group of four galaxies (SDSSCGB 5669), with a redshift of 0.369. This puts it at about 4.8 billion light years from the Milky Way.

SDSS J124938.39+411345.5 (upper right) is an emission line galaxy at a distance of 2.5 billion light years

 

Edited May 23, 2021 by wimvb

[peter shah]

wonderful image ...the outer halo is showing nicely

[wimvb]

Thanks, Peter. That was the original intention when aiming for this target. But unfortunately at the cost of the core. I think I have that fixed now. I had hoped to get finer detail in the core, but Northern European skies don't cooperate.

[wimvb]

Tweak nr 1, enhanced contrast and sharpened the core. I'm not quite sure which I like best.

[gorann]

Great image Wim! More details are always nice (new version) as long as it does not look artificial, and your image is far from reaching that state.

[geeklee]

Brilliant image Wim.  The way you've brought out the faint very outer disc is excellent.  So subtle, but clear.

I think I prefer image 1, but switching between them at full resolution, perhaps a blend of both.  The first image holds the faint stuff and transitions in and out of it really well (the second is also excellent!).

[Tom OD]

That’s a beauty.