M72 - Globular Cluster in Aquarius | Astrophotography Pictures and Tips
Messier 72 is a globular cluster located very close to another Messier object, M73. The cluster can be found in the constellation Aquarius approximately 54,570 light-years away.
Object Designation: M72, NGC 6981
Constellation: Aquarius
Object Type: Globular Cluster
Distance: 54,570 light-years
Magnitude: 9.3
Discovery: Pierre Méchain in 1780
M72 is bright but small, and is best captured with a large telescope. Being in Aquarius, M72, along with M73 which can be imaged in the same field of view with most setups, The pair is a good Summer astrophotography target.
M72 Astrophotography with a RASA 8 and Color Camera
September 2023
We shot M72 and M73 at the same time for 10 hours total using our fast RASA 8 f/2 telescope under the Bortle 2 skies of Utah Desert Remote Observatories.
The M72 cluster and the M73 asterism are so close to each other that it just makes sense to get them both in one go. one time as they both are very close to one another. We did 300-second exposures and, after 10 hours, hoped to see some IFN in the area which we did once the data was stacked!
GEAR USED:
Camera: ZWO ASI2600MC
Telescope: Celestron RASA 8
Mount: 10Micron GM1000 HPS
Guiding: ZWO ASI 220MM Mini
Accessories: Celestron Focuser / PrimaLuceLab Eagle 5S
Processing: Pixinsight, with R-C Astro plugins. Final touches in Skylum Luminar Neo
ACQUISITION DETAILS:
Total Exposure Time: 10 hours
Exposure Time per frame: 300 seconds
Filters: N/A
Gain: 100
How to Find M72
Messier 72 can be found about 54,570 light-years away in the constellation Aquarius, making is one of the most remote Messier clusters in the sky. It is right next to the M73 asterism.
Messier 72 appears faint and not impressive through an eyepiece. Only 4 or 5 central stars can be resolved, the rest is just part of the blurry blob.
M72 lies at the edge of the constellation Aquarius. The easiest way to find M72 is to start from the last bright star of Aquarius towards the constellation Capricornus, and go slightly south.
The best time to observe and photograph the M72 Cluster is in August.
Messier 72 Asterism Information
Messier 72 is a globular cluster believed to be about 9.5 billion years old. It is home to approximately 100,000 stars. So far, 43 stars within the cluster have been identified as variable stars.
Discovery
M72 was discovered on August 29h 1780 by Pierre Méchain.
This was the first of 5 clusters that Pierre Méchain would discover during his time assisting Charles Messier.
Messier confirmed the discovery and added to his catalog about a month later, on October 4th 1780. He wrote the following in his notes:
"Nebula seen by M. Méchain on the night of August 29-30, 1780, above the neck of Capricorn. M. Messier looked for it on the 4th and 5th of October following: the light is as faint as for the preceding [M71]; near it is a small telescopic star: the position was determined from the star Nu Aquarii, of fifth magnitude".
Messier 72 by the Hubble Space Telescope
NASA and ESA released a beautiful picture of Messier 72 taken with the Hubble Space Telescope, which you can see below.
This was achieved using the Wide Field Channel of the Advanced Camera for Surveys on the Hubble Space Telescope. The data was captured using yellow and near-infrared filters (F606W and F814W), with exposure times of about ten minutes per filter.
The image combines visible and infrared wavelengths and has a field of view of about 3.4 arcminutes. Can you spot the several galaxies visible around the cluster?
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How to Process Messier 72
Processing M72 is easy if you're just looking to get a good image without caring too much about revealing the very faint IFN around. If you do not care about the IFN, then you just need to stretch the image, take care of the noise, and play with the colors! There isn't any detail to bring out anywhere or intricate things to do to get a good image.
If you are looking to really show the IFN as best as possible, you will need to spend a good chunk of time carefully bringing out these faint particles of dust without making the rest of the image noisy. For this, play with masks and be very careful whenever you touch curves or the histogram.
Below you can see what a single 300-second shot looked like. As you can see, no IFN is visible at all and both M72 and M73 are difficult to spot.
If you'd like to learn how to process images with IFN in them (or ISM, another type of space dust), we strongly suggest taking a look at our 4K video walkthrough that shows all the techniques you can use to process such images. It also comes with high-resolution raw data!
Messier 72 FAQ
What is M72?
M72 is a globular cluster.
In which constellation is Messier 72 located?
M72 can be found in the constellation Aquarius.
How big is M72?
Messier 72 has an apparent size of about 6.6 arcminutes, and a diameter of 104 light-years.
How far is Messier 72?
M72 is believed to be around 50,570 light-years away from Earth.
How long should my exposure time be when photographing M72?
We recommend taking 30 to 60-second exposures if you want the cluster to look as crisp as possible. If you want the IFN in your shot, you'll need to take 5 to 10-minute exposures.
Should I use a filter to image M72?
M72 is a globular cluster with no apparent HA, SII, or OIII in its vicinity, so image it without filters!
What equipment do I need to photograph M72?
You can capture this object with any telescope, but the larger the better!
Final Thoughts
Messier 72 is small and faint globular cluster that is not as impressive as some other Messier globulars. It becomes much more interesting with the presence of IFN, although that is challenging to capture and process.
Have you imaged M72? If so, upload your picture in the comments! We'd all love to see your work :)
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