Messier 45, also known as the Pleiades, the Seven Sisters and Subaru among many other names is perhaps the brightest open cluster in the sky, at least in the northern sky. It consists of a bunch of hot, young blue stars that are passing through a patch of dust in the Milky Way. That dust reflects the light from the stars creating the blue glow around the stars.
This is 14 hours of RGB data taken two minutes at a time from a dark sky site in West Virginia. Imaging on this was only done when the moon was below the horizon. For the technical details you can see the astrobin page.
The cluster is, on average, about 440 light years distant and it spans almost two degrees of sky. It’s a n easy naked eye object, even in fairly bright skies. Over the centuries, many cultures have used it as a visual acuity test. The more stars someone could resolve, the better their vision. That’s a test I’d fail pretty badly 🙂
This is the second time I’ve tried to image M45. The earlier effort was my second deep sky image (here) and it was only 48 minutes of acquisition time from a very bright suburban sky. I’ve always wanted to go back to it and I’m glad I got the chance. Though I was hoping for at least 24 hours of data, bad weather in February and losing access to the dark sky site in West Virginia brought an end to image acquisition for this one. But, even with that limitation I’m super happy with how this one turned out. The amount to detail in the nebulosity is amazing!