Instrument

Takahashi FSQ-106ED @ f/5.0 (530 mm F.L.) Captured at 2.1 arcsec/pixel.  Shown at 4.2 and 7.53 arcsec/pixel.

Mount

Losmandy G11 with Gemini L4 v1.0

Camera

SBIG STF-8300M Self Guiding Package w/ mono ST-i, using Baader RGB filters.

Acquisition Data

6/24/2014 to 7/20/2014 Chino Valley, AZ... with CCDSoft & CCD Commander.

Exposure

Software & Processing Notes

• CCDSoft, CCDStack, PixInsight and Photoshop CS6.

• eXcalibrator v4.25 for (g:r) color balancing, using 260 stars from the SDSS-DR9 database.

• CCDStack to calibrate, register, normalize, data reject, combine the sub exposures and to create the RGB image.

• PixInsight for gradient removal and initial non-linear stretching.

• PhotoShop for final touch-up.

Comment

North is to the top.

IC 4665 is an open cluster in the constellation Ophiuchus. Philippe Loys de Chéseaux discovered it in 1745. At a distance of 1,100 to 1,400 light years, IC 4665 is approaching us at 12 km/sec. The cluster's very young age, about 35 million years, accounts for the beautiful blue hot stars. By comparison, our cooler yellow Sun is about 4.5 billion years old. The bright yellow and orange stars are not members of the cluster.

IC 4665 is easily seen with a small telescope or binoculars. With very dark skies, it is visible to the naked eye.