Messier 3

[Jkulin]

This was just a very quick session as we won't have any true Astro darkness for a couple of months.

I was unsure what I was going to do and then saw that M3 was ideally placed for me to grab a few hours as I didn't want to waste the lack of the moon.

I have reprocessed this about 3 times as I knew there was some nice gentle star colour, hopefully I have respected that they aren't strong but subtle colours.

Capture details: -

10" GSO/Altair RC Truss, Moravian G2-8300 Mk!!, iOptron 120EC Mount, Ultrastar Guide Camera, Chroma 2" Filters, QHY OAG. Processed in PI and PS 2020

Chroma Blue 2" unmounted: 8x390" -20C bin 1x1
Chroma Green 2" unmounted: 8x300" -20C bin 1x1
Chroma Luminance 2" unmounted: 11x300" -20C bin 1x1
Chroma Red 2" unmounted: 8x348" -20C bin 1x1

Further details here: - https://www.astrobin.com/7z8grc/

Anyway, here's the bumf: -

Messier 3 (M3 or NGC 5272) is a globular cluster of stars in the northern constellation of Canes Venatici. It was discovered on May 3, 1764, and was the first Messier object to be discovered by Charles Messier himself. Messier originally mistook the object for a nebula without stars. This mistake was corrected after the stars were resolved by William Herschel around 1784. Since then, it has become one of the best-studied globular clusters. Identification of the cluster's unusually large variable star population was begun in 1913 by American astronomer Solon Irving Bailey and new variable members continue to be identified up through 2004.

Many amateur astronomers consider it one of the finest northern globular clusters, following only Messier 13. M3 has an apparent magnitude of 6.2, making it a difficult naked eye target even with dark conditions. With a moderate-sized telescope, the cluster is fully defined. It can be a challenge to locate through the technique of star hopping, but can be found by looking almost exactly halfway along an imaginary line connecting the bright star Arcturus to Cor Caroli. Using a telescope with a 25 cm (9.8 in) aperture, the cluster has a bright core with a diameter of about 6 arcminutes and spans a total of 12 arcminutes.

This cluster is one of the largest and brightest, and is made up of around 500,000 stars. It is estimated to be 11.4 billion years old. It is located at a distance of about 33,900 light-years away from Earth.

Messier 3 is located 31.6 kly (9.7 kpc) above the Galactic plane and roughly 38.8 kly (11.9 kpc) from the center of the Milky Way. It contains 274 known variable stars; by far the highest number found in any globular cluster. These include 133 RR Lyrae variables, of which about a third display the Blazhko effect of long-period modulation.

The overall abundance of elements other than hydrogen and helium, what astronomers term the metallicity, is in the range of –1.34 to –1.50 dex. This value gives the logarithm of the abundance relative to the Sun; the actual proportion is 3.2–4.6% of the solar abundance. Messier 3 is the prototype for the Oosterhoff type I cluster, which is considered "metal-rich". That is, for a globular cluster, Messier 3 has a relatively high abundance of heavier elements.

https://en.wikipedia.org/wiki/Messier_3

Edited May 26, 2020 by Jkulin
typos

[geoflewis]

That’s a superb M3 John - I should know as I used to live just off Jct 4 before I moved to Norfolk. Seriously, your ‘Messier’ 3 is superb. I think that globular clusters are what saves the summer for LRGB imagers like me, as many of them are bright targets and can be captured pretty well in a bright sky, even with the Moon around in a summer sky.

[Jkulin]

Thanks Geof, I only grabbed that as a second thought, I've done M13 and M92 and from my location there aren't many I can image otherwise, so now what to capture over the next 4 nights?

[geoflewis]

1 hour ago, Jkulin said:

Thanks Geof, I only grabbed that as a second thought, I've done M13 and M92 and from my location there aren't many I can image otherwise, so now what to capture over the next 4 nights?

Well if you're thinking globular clusters, then M53 is not far from M3, albeit a bit lower and a bit further west. M5 is lower still and transiting just before midnight at about 40 degrees altitude, followed later on by M12, M10 and M14, though those are all even lower, transiting in the low to mid 30s degrees altitude, so if altitude looking south is a problem then maybe they're not possible.

[Jkulin]

Thanks Geof, I think I'm sorted for this week, but will put M53 on the list for the next object after this session. M5 is always a problem with it being low behind the trees for me, so I doubt I will be able to grab that from my location.

[MarkAR]

Lovely image, nice colour stars.