This image is a mosaic of 4 Ha images of 14+12+12+17 images of 1800s each. The total exposition time is 27hr 30m. The telescope used is FSQ and QHY90A the CCD. The frame were taken on July 2016.
The Veil Nebula is a cloud of heated and ionized gas and dust in the constellation Cygnus. It constitutes the visible portions of the Cygnus Loop, a supernova remnant, many portions of which have acquired their own individual names and catalogue identifiers (NGC6960,6992,6995,6974,6979 and IC1340). The source supernova was a star 20 times more massive than the Sun, and it exploded between 10,000 and 20,000 years ago. The remnants have since expanded to cover an area of the sky roughly 3 degrees in diameter (about 6 times the diameter, and 36 times the area, of the full Moon). While previous distance estimates have ranged from 1200 to 5800 light-years, a recent determination of 2400 light-years is based on direct astrometric measurements. (The distance estimates affect also the estimates of size and age.) (Wikipedia).