NGC 6995, The Bat Nebula
RA (J2000): 20h 56m 14s
Dec (J2000): +31 degrees 26' 07"
Position Angle: 90 degrees
Bat Nebula (NGC 6995) is located in the eastern portion of the Veil Nebula
Complex. This entire region is created by an expanding
shockwave resulting from a supernova that exploded approximately 8,000
years ago. The shockwave slams into surrounding dust in the
interstellar medium, ionizing gases such as hydrogen, oxygen, and
sulfur, which emit specific wavelengths of radiation during electron
recapture. The above image was taken though two filter, one that
passes radiation from singly ionized hydrogen (HII, Hydrogen Alpha,
656.3 nm, shown in red) and another that passes radiation from doubly
(OIII, 496nm and 501nm, shown in blue). The result is a
beautiful, lacelike structure that has fascinated astronomers since its
original discovery in 1784 by William Herschel. The
filamentous structure of the nebula results from the fact that we are
viewing the thin shockwave fronts edge-on.
Dates: August 23,
FSQ106 at f5 on the Takahashi NJP
Autoguider: ASI178 autoguider with SvBony 30mm guidescope, focal length
Camera: ZWO ASI294MM at -10C,
7 position ZWO filter wheel. Pixel size is 2.3 microns (Bin 1x1),
yielding an image scale with the FSQ (530mm focal length) of 0.90
"/pixel (well matched for my seeing of 3 arcseconds).
Camera gain set to 50 (e-gain
2.13 electrons/ADU), offset 25.
Read noise at this gain level was 2.18 electrons rms.
Ha, OIII filters; 2 inch.
software: MaximDL for camera control and autoguiding; CCD
Commander for automation.
exposure 4 hours (Ha: 2 hours, 300 second subs; OIII 2 hours, 300
integration, deconvolution (BlurXTerminator), noise reduction
Pixinsight; subsequent processing in Photoshop.
note: Graphics on this website may not be reproduced without
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