Astro Anarchy: February 2018

Tuesday, February 6, 2018

Sharpless 157 in Cassiopeia, project continues

Few weeks ago I published a new photo of Sharpless 157, it can be seen HERE. We had one of

the rare clear nights at last Sunday night. I managed to get just enough exposures to add a second frame to this two frame mosaic image of Sh2-157.

Sharpless 157 (Sh2-157)
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Image is in mapped colours, from the emission of ionized elements, R=Sulphur, G=Hydrogen and B=Oxygen. The photo width is about one degree of sky. (The full Moon covers about 0,5 degrees of sky.)

An experimental starless version
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A closeup
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Detail from middle right

INFO

Sharpless 157

The night sky between the constellations Cassiopeia and Cepheus is rich with nebulae and star clusters. The nebulae visible in this image include Sharpless 157 and Lynd’s Bright Nebula 537. The star clusters include Markarian 50 and NGC 7510. The planetary Nebula PLN 110-0.1 (WeSb) can be seen at lower left.

Sharpless 157 is sometimes referred to as the Lobster Claw Nebula for obvious reasons. The bright spot at upper left quarter of this photo is Lynd’s Bright Nebula (LBN) 537. Also designated at Sh 2 – 157a, it is a ring nebula around the Wolf-Rayet star WR 157.

At the lower right quarter of the image lays open star cluster NGC 7510.

With labels
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An older wide field photo of the area
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The area of a new photo is marked as a white rectangle. The Bubble nebula can be seen as a bluish pearl, just half a degree North West from the Sharpless 157.

This photo is shot at 2007 with a QHY 8 astrocamera and the Baader narrowband filter set, H-a, S-II and O-III

Technical details

Processing work flow

Image acquisition, MaxiDL v5.07.

Stacked and calibrated in CCDStack2.

Deconvolution with a CCDStack2 Positive Constraint, 33 iterations, added at 50% weight

Color combine in PS CS3

Levels and curves in PS CS3.

Imaging optics

Celestron Edge HD 1100 @ f10 with 0,7 focal reducer for Edge HD 1100 telescope

Mount

10-micron 1000

Cameras and filters

Imaging camera Apogee Alta U16 and Apogee seven slot filter wheel

Guider camera, Lodestar x 2 and SXV-AOL

Astrodon filters,
5nm H-alpha 3nm S-II and 3nm O-III

Exposure times

H-alpha, 24 x 1200 s, binned 2x2 = 8 h
O-III, 10 x 1200 s, binned 4x4 = 3 h 20 min.
S-II, 9 x 1200 s. binned 4x4 = 3 h
Total 14 h 20 min

A single uncropped, calibrated and stretched 20 min. exposures as they come out from the camera.

H-alpha