Astrophotography Session in Early November

Clear skies are hard to come by these past 2 years, so when they do come along you gotta take advantage of them. Early November was a good time - clear skies, no moon.

First up is the Eastern Veil Nebula, NGC 6992. The Veil Nebula is a cloud of heated and ionized gas and dust in the constellation Cygnus. It constitutes the visible portions of what is known as the Cygnus Loop, a supernova remnant, many portions of which have acquired their own individual names and catalogue identifiers. The source supernova was a star 20 times more massive than the Sun, which exploded around 8,000 years ago. The remnants have since expanded to cover an area of the sky roughly 3 degrees in diameter (about 6 times the diameter, or 36 times the area, of the full Moon). (Wiki)

The complete nebula is too large to capture in a single image and would require a multiple image mosaic. But that would require a lot of time (and some techniques that I have not mastered yet).  So I've imaged the eastern section by itself. The nebula was captured over two nights, November 3 and 10, 2018, with a total exposure time of 5 hours. Using a monochrome camera with narrowband (NB) filters the resultant bi-color photo was a combination of thirty, five minutes exposures in both the Hydrogen Alpha wavelength, Ha, and the doubly ionized Oxygen wavelength, Oiii. This combination, applying the Ha to the red channel, and the Oiii to the green and blue channels produces what is known as an HOO image.

NGC 6992 - The Eastern Veil Nebula
Nov 3 & 10, 2018 - WO GT102 APO Refractor (4", f/5.6)
ASI1600mm Pro Camera - 30x300sec Ha; 30x300sec Oiii

Next is NGC 7380 (also known as the Wizard Nebula) which is an open cluster discovered by Caroline Herschel in 1787. William Herschel included his sister's discovery in his catalog, and labelled it H VIII.77. It is also known as 142 in the 1959 Sharpless catalog (Sh2-142). This reasonably large nebula is located in Cepheus. It is extremely difficult to observe visually, usually requiring very dark skies and an O-III filter.

Located 7200 light years away, the Wizard nebula, surrounds developing open star cluster NGC 7380. Visually, the interplay of stars, gas, and dust has created a shape that appears to some like a fictional medieval sorcerer. The active star forming region spans about 100 light years, making it appear larger than the angular extent of the Moon. (Wiki)

Similar to the process of imaging the Veil, the Wizard Nebula was captured using the two NB filters, Ha and Oiii, but also merging in the complete RGB for capturing the correct color of the stars. This image is typically named RGBHOO. Captured on Nov 10 and 11, 2018, it is the result of 2.4 hours of exposure (15x60sec in each color, RGB, and 10x300sec in the NB).

NGC 7380 - The Wizard Nebula
Nov 10 & 11, 2018 - WO GT102 (4"; f/5.6)
ASI1600mm camera - 15x60sec each RGB; 10x300 Ha and Oiii