Instrument

12.5" RCOS @  ~f/9 (2897 mm fl) 0.641 arcsec / pixel.  The Zoomify image scale is 0.85 to 3.07 arcsec / pixel.

Mount

Paramount ME

Camera

SBIG STL-11000 w/ internal filter wheel, AstroDon Gen II Filters

Acquisition Data

4/2/2011 to 5/5/2011 Chino Valley, AZ... with CCDAutoPilot3 & CCDSoft.  AOL guided

Exposure

Lum 495 min (33 x 15 min, bin 1x1...  best 33 of 40)

RGB 675 min (15 x 15 min each, bin 2x2)

Software

CCDSoft, CCDStack, Photoshop CS3, Noel Carboni's actions and Russell Croman's GradientXTerminator.

Color balance by MBG (my best guess)

PixFix32 (pre-beta) to repair column defects.

CCDStack to calibrate, register, normalize, data reject,  combining the sub exposures and LRGB combine.

PhotoShop for non-linear stretching, LLRGB combine.

Noiseware Pro, a PhotoShop plug-in.

North is to the top.

NGC 4395 is a remarkable low surface brightness spiral galaxy, about 26 million light-years from Earth, in the constellation Canes Venatici. In addition to being a Seyfert 1 Galaxy, NGC 4395 is noted for having the smallest known central black hole. Galactic black holes typically weight in at a million to a billion solar masses. NGC 4395's black hole is only 300,000 to 400,000 solar masses.

When viewed edge-on, galaxies typically have a central bulge. NGC 4395 has no bulge; it is essentially a flat disk. This odd shape may be linked to the size of the black hole. It may have already "eaten" all the stars in the center of the galaxy. This would also explain why the black hole doesn't seem to be growing and has a small size.

This image was used in a 2016 publication by Amy E. Reines and Andrea Comastri.
Observational Signatures of High-Redshift Quasars and Local Relics of Black Hole Seeds