In one of my previous post I mentioned how Messier 44, the Beehive Cluster, would be an easy find the evening of April 22-23, so even if I took this photo on the 21st, the same evening that I took a photo of the Moon, all I needed was to moved a few degrees north after observing the Mooon to image this large open cluster.
Messier 44 – Beehive Cluster. Benoit Guertin – taken with Skywatcher 80ED and Canon 80D
Photos of open clusters with small refractors always lack the diffraction spikes that really make the stars stand out. So a little photo editing did the trick to spice up the image.
Canon 80D ISO 3200
Stacked 22 x 10sec
The Beehive cluster, also known as Messier 44 (M44) is one of the nearest open clusters, and therefore one of the largest in the night sky. While open clusters are often too dim to be seen with the naked eye, all you need is a pair of binoculars or a camera with long exposure to see it.
What makes this weekend special is that in the night of the 22nd to 23rd of April, the Moon will pass within 1-1/2 degrees of this cluster. So finding it will be child’s play.
Messier 44 – Open Cluster Benoit Guertin
On April 22nd, simply look for the Moon once the sky is dark, and just above it you will find the Beehive cluster with its 1000+ stars. OK, even with a telescope you won’t be able to see all the stars, but take some time to notice how this group of stars stands out with regards to background stars further away in our galaxy. And while you are at it, consider that nearly 410 years ago, Galileo made the first observation of these stars.
From there you can also hop over a to the west and observe the color difference in bright stars Castor and Pollux in the Constellation Gemini. And if you instead decide to go east, the smaller Messier 67 open cluster is also accessible with binoculars.
Not too far my previous post’s open cluster lies a smaller and younger NGC 6709. Both were imaged on the same evening, but I only got 15 minute of integration due to advancing clouds. However with these open clusters, I don’t think a greater number of frames would amount to much more details.
Open Cluster NGC 6709
Canon Rebel XTi
30 x 30sec (ISO 400)
Open star clusters are the galaxy’s youngest stars. They are created from the collapse of giant molecular gas clouds, often forming large and very hot stars shinning brightly in the blue-white part of the spectrum. As they are rapidly consuming their fuel, they are also short-lived. By ending as a super nova, they create the heavier elements beyond carbon that exists all around us.
Below is open star cluster NGC 6633, estimated to be 660 million years old (our solar system is 4.6 billion years old). The cluster is of a decent size covering just about the size of a full Moon in the night sky. The brighter and whitish stars stand out against older and further stars in the background.
Open Star Cluster NGC 6633
Younger star clusters such as the Pleiades (Messier 45) have yet to burn away their molecular gas clouds. However there is no hint of glowing gas (nebula) with NGC 6633.
Canon Rebel XTi
51x30sec (25.5 minutes) ISO 400
An easy target for anyone is the constellation Auriga and it’s three bright open star clusters. It may be considered a winter constellation, but there is still plenty of time for some decent observation. In the early April evenings , Auriga lies west about 45 degrees over the horizon. It’s brightest star, Capella, the sixth brightest in the night sky can easily be located. Therefore these open clusters are easy targets for a quick star-hopping observation for anyone with a small telescope or binoculars.
Auriga in April with three bright open clusters (boxed)
My last few posts have been the photos that I’ve captured of these three Messier objects: M36, M37 and M38. Below is a view if the boxed area from above but with the photos of the open clusters inserted at their correct location.
M37, M36 and M38 (respectively) in Auriga
To see larger images of the open clusters, refer to my following blogs:
Following my previous post on Messier 36, a simple 2 degree slew of the telescope and I was centered on Messier 38 (NGC1912). This open cluster measures 21 light years across ( 21′ apparent) or twice the size of M36. It is also much older than M36 which is why you’ll find less hot blue stars within the group if you compare with M36.
Just half a degree below is an older and smaller open cluster NGC1907. While some have speculated that they are locked together (a binary cluster?) this cluster is 500 million years old, almost twice the age of M38, hence were formed at different periods and most likely from different molecular gas. This is just a chanced fly-by with no interactions.
Open Clusters Messier 38 and NGC1907
Canon Digital Rebel XTi (400D)
30 x 30sec (ISO 800)
Registration with IRIS
Post-Processing with GIMP
Open Cluster Messier 36 (NGC 1960) is located in the Auriga constellation. Located about 4,100 light years from Earth, and 14 light years across, it has at least 60 members. It is very similar to the Pleiades (M45) and if M36 was at the same distance (M45 is 10 times closer) it would be of similar magnitude. Two other open clusters from Messier’s catalog are located nearby: M37 and M38. The stars in the cluster are of spectral type B2, and fairly young: 25 million years.
Open Cluster Messier 36. Skywatcher 80ED, Canon 400D 18x30sec
The blue-ish stars contrast with the older yellow and orange stars in the background. This can be further enhanced by using the SBLUR function in IRIS to selectively blur and enhance the colors of bright stars. While the colors are exaggerated in the image below, it is nevertheless interesting to see the vast diversity of stars and their color.
Open Cluster Messier 36. Skywatcher 80ED, Canon 400D 18x30sec (SBLUR for colour)
Telescope: Skywatcher 80ED
Camera: Canon Digital Rebel XTi (400D)
Exposure: 18 x 30sec (ISO 800)
On the same night that I imaged Messier 44 I decided to hop over to another nearby open cluster: Messier 67. While M44 appears three times larger, both of these open clusters are estimated to be of roughly the same size, but M67 happens to be 5 to 6 times farther away.
Click on the image to get the full image, it’s scaled and cropped below.
Open Cluster Messier 67 Benoit Guertin
Telescope: Sky-Watcher 80ED
Camera: Canon XTi (ISO 400)
Image: 19 x 30sec
Welcome to a journey into our Universe with Dr Dave, amateur astronomer and astrophotographer for over 40 years. Astro-imaging, image processing, space science, solar astronomy and public outreach are some of the stops in this journey!