I had a failure of my telescope (the mount) several weeks ago and have not been observing. If I’m going to have a failure like this, the best time is probably around the end of June when there is little darkness for astronomy. The circuit board is now repaired and very slowly coming north from Massachusetts via the post.
I took a look at the images that I feel are suitable for printing and decided I would clean up a favourite target, the “Bubble Nebula”. The data for this image was collected in two sessions back in 2022. I have another image of this target that I like very much (see image 3 below) but it is very different, showing only the bubble and its immediate area. With this small field of view the stars are fairly bloated and I’m not sure it will look good as a print without some more work.
Image 1: Wide-Field image of the Bubble Nebula and neighbouring objects.
This image is of a fairly large field of view, 2.6 by 1.9 degrees, but it has detail at the level of a few arcseconds, which will not be seen on a low-resolution image or on a print. The image is centred at 11h18m Right Ascension and 61 degrees north declination. Image 2 is a cropped version showing just the area of the bubble to illustrate the detail. Both of these (Image 1 and 2) seem good for printing.
Image 2: Crop of image 1 showing the immediate area of the Bubble.
Image 3: My previous image of the Bubble, from 2021.
The bubble is in the Cassiopeia constellation, the giant “W” in the northern skies. Years ago I learned that the Canadian professional astronomers called their newsletter “Cassiopeia” because it was so prominent in the northern skies and was always visible. Since then I’ve considered it the “Canadian Constellation”. My blog is “Gamma Cassiopeia”, the name of the star “Navi”, centre of the W. I have also spent many years working on Positioning, Navigation and Timing issues.
Cassiopeia was a Queen of Ethiopia and the mother of Andromeda in Greek mythology, who boasted about her unrivaled beauty. The gods didn’t take too kindly to her hubris and part of her punishment was to wheel around in the northern skies, upside down half the time. The constellation is one of the original ones in the European tradition, listed by Ptolemy in the 2nd century.
The giant W is not shown here, but if we follow a line from the cluster at the upper right down through the bubble we will soon hit the giant W. Some of the objects are in the neighboring Cepheus constellation. This region of the sky is in the bright stripe of the Milky Way galaxy as seen from Earth. That is, we are looking along the plane of the galaxy where there is lots of gas and dust and newly formed stars and nebulae. No other galaxies are visible because there is too much junk in the way.
The Bubble Nebula is an emission nebula: The "bubble" is created by a hot young star (44 solar masses?) heating up its neighborhood. The nebula is near a giant molecular cloud which is the material seen in the shell of the bubble. The bubble nebula was discovered in 1787 by William Herschel.
It is fairly small as seen from Earth (a few arcminutes across) but the bubble is actually around 4 light years in diameter. That doesn't sound like much but consider that Saturn is 1.3 light HOURS away from our sun. Our sun and all its planets would be insignificant specks inside this bubble.
Other objects in the image:
The small star cluster in the upper right is NGC7510, also called the “Dormouse Cluster” or the “Arrowhead Cluster”.
The small bright red nebula in the upper left is NGC7538, also called the “Northern Lagoon Nebula”, or the “Brain Nebula”.
The large faint nebula in the upper right is the Lobster Claw Nebula, AKA LBN540 or Sh2-157. I think it looks like a cartoon rocket ship.
The very bright spot in the Lobster Claw is called SH1-109.
The open star cluster at the bottom of the image is M52 or NGC7654, also called the “Scorpion Cluster”.
The Bubble Nebula itself is NGC7635, located in the lower centre of the image.
On the right of a line drawn from the Bubble to the Brain Nebula is a faint red patch, known as SH2-159 or LBN154. The fainter red patch to the left of this line is SH2-161 or LBN547.
Finally, the bright star at the bottom left of the image is “4 Cassiopeia”, a star in the constellation Cassiopeia. It is a red giant star, magnitude 5, 800 light years away from us. The stars of the W are all around magnitude 2 or 3, so they are much brighter. 4 Cassiopeia is bright enough to be visible with the naked eye.
A NOTE ON NAMING NEBULAE:
The “M” in M52 stands for Messier, who is responsible for the Messier catalogue of objects visible from Paris that are not comets but might have been confused for such (1770s). NGC refers to the New General Catalogue of Nebulae and Clusters of Stars, initially compiled in 1888 from the observations of Caroline and William Herschel. LBN stands for Lynds' Catalogue of Bright Nebulae, the work of US astronomer Beverly Turner Lynds in the 1960s. SH1 and SH2 refer to the two volumes of the Catalogue of H II Regions, published in 1959 by US astronomer Stewart Sharpless.
For observers in the northern hemisphere, the brightest objects will typically be in the Messier catalog and I will use that name first. The NGC catalogue is much larger and I will typically use this name next. More obscure objects will be named using SH or LBN or other names, which I will use only if there is no M or NGC name.
Image produced by combining RGB data with Hydrogen Alpha narrowband imagery. The H Alpha data was collected in January 2022 and the RGB data was collected in September 2022. Roughly one hour of each data type was used (~60 subframes of 60 seconds each) and images were increased 2x in stacking. The telescope was the RASA11 and the cameras were ZWO ASI 6200 MC (RGB) and MM (H Alpha). The luminosity channel was the H Alpha, and the RGB provided the colour. Note that the images were manually aligned in GIMP: Offset, rotation and a tiny amount of stretch!
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