Instrument

12.5" RCOS @ ~ f/9 (2880 mm fl) at 0.64 arcsec/pixel. Shown at  1.30 & 3.37 arcsec/pixel.

Mount

Paramount ME

Camera

SBIG STL-11000 w/ FW8 filter wheel & AstroDon Gen-2 RGB filters.

Acquisition Data

9/6/2018 to 10/9/2018 Chino Valley, AZ. with CCD Commander & CCDSoft.  AOL guided

Exposure

eXcalibrator RGB ratios are 1.00, 1.17 & 1.21

Software & Processing Notes

• CCDSoft, CCDStack, PixInsight, Photoshop CS6.

• eXcalibrator v6.2 for (g:r),(b:r) color balancing, using 203 stars from the Pan-STARRS database.

• CCDBand-Aid to repair KAI-11000M vertical bars.

• CCDStack to calibrate the all sub exposures and to data reject and mean combine the color data.

• PixInsight to register, data  reject, mean combine the luminance sub exposures, create the LRGB image, gradient removal, non-linear stretching with HistogramTransformation, color saturation, green cast removal with SCNR and selective detail enhancement with HDRMultiscaleTransform.

• PhotoShop for additional background neutralization, background smoothing, removal of a strong reflection, selective sharpening and JPEG creation. 

• Noiseware 5, a PhotoShop plug-in.

Comment

Shown rotated 60° clockwise.

At the image bottom is the blue reflection nebula, Cederblad 201 . The extended dark nebula is cataloged as Barnhard 175. Together, they are known as Van den Bergh 152, in the constellation Cepheus.

Max Wolf's assistant, August Kopff, photographically discovered the complex structure on October 21, 1908. To Wolf, it looked like a cave and he started calling it the Cave Nebula. Wolf also thought the nebula was an actual cave formation in the Milky Way stars. It was finally designated as vdB 152 and is still sometimes called Wolf's Cave.

Here is Max Wolf's Dec. 1908 announcement in the Monthly Notices of the Royal Astronomical Society, Vol. 69, p.117