Each month I will focus on one object which is available in the Galaxy on Glass range. This month I have chosen the beautiful Pickering’s Triangle.
Pickering’s Triangle is one section of what is known as a supernova remnant – the remains of a giant exploded star.
Stars have a lifetime. How they live, and die depends largely on their size, or more accurately, their mass. Giant stars, those 8X more massive than our Sun have relatively short lifetimes, ending in massive explosions when virtually all the remaining material is blasted out into space. This is known as a supernova explosion.
Pickering’s Triangle is a supernova remnant: the remains of such an explosion – a shockwave of gas, dust and plasma moving through space. It is estimated the original supernova explosion took place around 8000BC. Pickering’s Triangle can be located in the constellation of Cygnus the Swan, riding high in the northern Hemisphere sky during the summer months. It is actually just one part of a major shock wave known as the Cygnus Loop or the Veil Nebula. I have imaged other parts of the Veil, including The Witch’s Broom and the less romantically named section, NGC 6992. All are available in the Galaxy on Glass Original Collection.
The entire Veil is estimated to be around 2,400 light years away. When finely resolved, some parts of the nebula appear to be rope-like filaments. The shock waves are so thin, less than one part in 50,000 of the radius, that the shell is visible only when viewed exactly edge-on, giving the shell the appearance of a filament. Here is an expanded view from my image of some of the stunning filaments:
Imaging Pickering’s Triangle
This object is extremely faint from Earth and not much light is reaching the telescope and camera. In addition it emits light at specific wavelengths associated with certain ionized states of gases.
I use specialist filters which capture certain emissions from these gases, in this case Hydrogen Alpha (Ha), Oxygen III (OIII) and Sulphur II (SII). Using my telescope and cameras I captured around 30 hours of data through these three filters over many nights. Each exposure was 25 minutes and at the end of each night I discard the sub optimal images, such as when the seeing conditions were not perfect or a satellite crossed the field of view. Over time I build up the data for each filter and eventually have enough to start the long process of calibration and processing.
During this process I want to extract the beautiful detail that exists buried within the raw data and at the same time make it look stunning for the Galaxy on Glass range. I use a convention to assign the colours developed for the Hubble Space telescope. This means that I assign the SII to the red channel, Ha to the green and OIII to the blue channel. You will see in this picture that there is a lot of blue, meaning the object is emitting a lot of light associated with the ionized Oxygen. Using this convention shows rich blues and golds and the wispy details of the nebulosity.
View the availability of Pickering’s Triangle.