Instrument

Takahashi FSQ-106ED @ f/5.0 (530 mm F.L.) Captured at 2.1 arcsec/pixel.  Shown at 2.93 and 5.19 arcsec/pixel.

Mount

Paramount MyT

Camera

SBIG STF-8300M Self Guiding Package w/ mono ST-i, using AstroDon E-Series LRGB filters.

Acquisition Data

2/15/2017 to 2/25/2017 Chino Valley, AZ. with CCD Commander & CCDSoft. 

Exposure

eXcalibrator RGB ratios are 1.00, 0.97 & 0.99

Software & Processing Notes

• CCDSoft, PixInsight, Photoshop CS6.

• eXcalibrator v6.2 for (g:r),(b:r) color balancing, using 1232 stars from the SDSS-DR12 database.

• PixInsight to calibrate, register, data  reject, mean combine, background clean-up with CosmeticCorrection,  create the RGB image, gradient removal, non-linear stretching with HistogramTransformation & color saturation.

• PhotoShop for additional background neutralization.

Comment

North is to the top.

Charles Messier discovered M48 in 1771. Charles mistakenly cataloged the cluster's location. This lead to later independent discoveries by Elert Bode in 1782 and Charles's sister, Caroline Herschel, in 1783. Charles published his sister's discovery in his catalog as H VI.22 on February 1, 1786.

The cluster spans roughly 23 light-years and lies about 1,500 to 2,000 light-years away, toward the constellation of Hydra. M48 is about 300 million years old, still young enough to have many young bright blue stars. Clusters, like this, are loosely bound by gravity. As they age, the clusters spread out and the member stars slowly escape.