The two major diffuse nebulae M16 "Eagle Nabula" and M17 "Omega Nabula," and surrounding area are captured in a mosaic composition of two panels taken by QHYCCD's new APS-H size cooled CCD camera QHY16200A. Especially, Sharpless 54, located in the north of the major nebulae, attracted me with its subtle color undulation behind cloud of stars. Also, see the color contrast of the remarkable blue star on the left and sh2-54 the right. This star is at the center of the cluster NGC6625 and has magnitude of 5.69, but apparently does not have any unique name.

Processing Note:

All processes were in PixInsight. RGB frames from DSLR were integrated with BayerDrizzle, and composite with LRGBComposition. Mosaic was processed with GradientMergeMosaic with helps of template creation by CatalogStarGenerator script to correct distortion. Post process includes compression and local contrast enhancement with HDRMultiscaleTransform and LocalHistgramEqualization as well as conventional nonlinear techniques such as CurveTransformation. Deconvolution was employed only for B channel to eliminate influence of chromatic aberration Borg 55FL has.

Detailed acquisition information is as follows:

[Exposure Time]

L Images:

2016/8/8 21:33-23:50

300 secs x 25 frames, total exposure 125 minutes

RGB Images:

2016/8/8 21:30-23:49

140 secs x 48 frames, total exposure 112 minutes

Total exposure time: 237 minutes

[Equipment]

Equipment for L:

Borg 67FL + 7108 reducer, fl324mm F4.8

QHYCCD QHY16200A mono, -13 degrees Celsius

Equipment for RGB:

Borg 55FL + 7880 reducer, fl200mm F3.6

Cannon EOS Kiss X4 (IR modified), ISO1600

Common Equipment:

Mount: iOptron CEM60

Guiding Telescope: Takahashi GT-40

Guiding Camera: QHYCCD QHY-5IIL

Capturing Software: APT Version 3.12

Guiding Software: PHD2 Version 2.61

Processing Software: PixInsight 01.08.04.1195

Photoshop CC

L images for the LRGB was composition of images with cooled CCD Camera QHY16200A, while RGB images were from DSLR EOS Kiss X4.