While waiting to be able to resume planetary and lunar imagery (bad weather conditions),

I was delighted again, trying to best deal with the raw data provided so amicably by Jim Misti, whom I thank again.

From what I have read about it, NGC 4725 is a barred spiral galaxy, located about 41 million light-years from Earth, in the direction of the constellation Berenice's Hair. From The Earth it is seen from an angle of 11 minutes (or 1/3 of the Full Moon) corresponding to a diameter of 130,000 light-years (identical to that of the Milky Way).

When one observes this galaxy carefully, one notices that it has only one spiral arm. Most galaxies, such as the Milky Way, are composed of two or more spiral arms rotating around a central nucleus. It is clear that the single arm is wrapped around an elongated nucleus is punctuated by clusters of young blue stars. This particular arrangement made it considered by astronomers as the model of a banded barred spiral galaxy.

The brightness of the central region, higher than normal, indicates that NGC 4725 is an active galaxy. This phenomenon is probably caused by an accretion disk orbiting a super-massive black hole located in the center of the galaxy.

NGC 4725 belongs to the category of "Seyfert galaxies". Seyfert galaxies are active, spiral or irregular galaxies, containing an extremely bright nucleus.

For this treatment, I used 3 software, Siril, IRIS and Photoshop.

Siril used me mainly to combine RGB channels and color balancing treatments and deep heaven. I gave up integrating luminance, impossible to get a correct result.

IRIS on the other hand was excellent for achieving an ideal luminance.

I then realized the combination L and RGB with Photoshop and all the adjustments necessary to get a presentable image, I hope.

Thank you for any comments and/or advice.

Image acquisition by Jim Misti.

Ritchey-Chretien 32“ telescope

Camera SBIG STL 1100

Luminance 12x5 mn

4x5 mn RGB

2016