Image 1: M101 the Pinwheel Galaxy with companion NGC5474, imaged in April 2023 from Lac Teeples. This is my blended version.
Image 2: M101 the Pinwheel Galaxy with companion NGC5474, imaged in April 2023 from Lac Teeples. This is my "crispier" editing.
Messier 101, M101, or the Pinwheel Galaxy, is a large and fairly commonly observed galaxy. It is not one of our nearest neighbors, but it is close enough that it is fairly large in the sky, 28 by 27 arcminutes. That is nearly as big as the moon, but it is so faint you need quite a telescope to see all of this.
I’m writing this in late October, a very poor time to observe this galaxy. The Telescopius website (used in astronomy planning) tells us that the ideal time to see it (at 10pm) is in early June. The image was actually captured in April 2023 but I simply never completed it. The main reason (aside from laziness) is that I had a very nice image from a few years ago (Image 3) and I wasn’t satisfied with the new one. I’ve finally decided to clean it up as much as I can and post it.
There are two versions here. One is very crisp and sharp but it is also noisy if you look at in close up (image 2). The other is soother, with a smooth version merged with the sharp one (image 1). Both look quite good!
Image 3: M101 the Pinwheel Galaxy with companion NGC5474, imaged in March 2021 from Lac Teeples
In spring and summer 2019 I was struggling with poor skills and poor equipment trying to image astronomical objects. I chose to look at M101 and worked away at it. Finally in July I managed to get an image which showed the galaxy and some of the spiral arms. It was blurry and faint but that was my first decent astrophotography image. I was delighted. A slightly cleaned up version of that image is shown below (Image 4).
Image 4: M101 the Pinwheel Galaxy, imaged in July 2019 from Lac Teeples
M101 is a very nicely structured “grand design spiral” galaxy that is reasonably close to us, is reasonably bright (not obscured by junk in the Milky Way) and is face-on so we have a great view of the spiral structure. It was discovered by Geodesist Pierre Mechain in 1781 and then verified by Charles Messier for placement in his catalogue, where it is one of the final entries.
The Wikipedia article claims that it can be seen with binoculars, but it would be quite difficult and would likely appear like a dot of light, hard to distinguish from a star. Pierre Mechain said that it was only 6 or 7 arcmin across, so he only was able to see the bright core with the equipment he had at hand. With a decent telescope and a camera it is easily imaged today.
Our own galaxy, the Milky Way, is also a spiral (probably not as "grand") and has a few hundred billion stars. M101 is estimated to have 1 trillion, so it is 2 or 3 times bigger than the Milky Way. That’s big! The diameter of the disk is roughly twice that of the Milky Way. Overall it is probably more like the Andromeda galaxy than our home galaxy.
There are many nebulae that are star formation regions glowing red with Hydrogen-Alpha emission. My new image shows these regions fairly clearly. I have cropped the image to include a companion galaxy, NGC5474 which is interacting with M101.
I notice that many images on the web show the arms with a blue tint. There is a Hubble image that is very blue. I noticed that some of the Hydrogen-Alpha regions (at a specific RED wavelength) are also showing as blue in some of these images. That is impossible. Overall I suspect that the colour balance may be slightly off but I suspect it is truer to the real colours than most images on the internet of this object.
Image 1 was captured using the RASA-11 telescope and the ZWO ASI6200MM and MC cameras. It is an RGB colour image with Hydrogen-Alpha narrowband imagery superimposed. There are approximately four hours of data involved in this image.
Image 2 was captured with the RASA-8 telescope and the ZWO ASI6200MC camera. It is an RGB image.
Image 3 was captured with a Celestron 8" Schmidt- Cassegrain telescope and the ZWO ASI-294 camera.
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