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Globular Clusters

M13 (2025-05-19)

I imaged the Great Hercules Cluster and two elusive galaxies

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I imaged the Great Hercules Cluster and two elusive galaxies

Less than 1 minute Minutes

I captured this image of the beautiful globular cluster M13 from my backyard through my ES ED80CF telescope with just 1 hour of total integration time. In the annotated image I highlighted two faint galaxies, NGC 6207 (30 million light-years away) and IC 4617, which is about 553 million light-years away!

M13, located about 25,000 light-years from us in the constellation Hercules, is a dense sphere of hundreds of thousands of ancient stars, making it one of the brightest and most spectacular globular clusters visible from the Northern Hemisphere.

In 1974, the Arecibo Observatory famously sent a radio message toward M13, encoding information about humanity in hopes of reaching distant intelligences – though the message will take about 25,000 years to arrive, by which time M13 will have shifted in the sky.

Imagine, among the myriad stars of M13, a hypothetical planet tidally locked to its sun, where one side always faces the star. On this world, it is perpetually daytime – with a crowded sky of the cluster’s core, where stars are packed up to a hundred times more densely than in our own stellar neighborhood!

M13 (2025-05-19)M13 with annotations (2025-05-19)
M3 with annotations (2025-05-19)

From my backyard to Light-Years: Imaging the M3 Globular Cluster

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From my backyard to Light-Years: Imaging the M3 Globular Cluster

Less than 1 minute Minutes

On May 19, 2025 the sky was clear with cool temperature – perfect conditions for astrophotography without any interference from mosquitoes. I turned my telescope toward some of the season’s rising globular clusters. My first target for the night was Messier 3, a spectacular globular cluster in the constellation Canes Venatici (the Hunting Dogs).

The image below is the result of a one-hour integration, captured using an ES ED80APO CF refractor paired with a ZWO ASI533MC Pro (my one-shot color camera). To reduce light pollution, I used an Optolong L-Pro filter, with guiding provided by an Orion Mini 50mm scope and a ZWO ASI224MC camera. I used the Juwei 17 harmonic drive mount, controlled by a Mele Quieter 4C mini PC running NINA. Image processing was done in PixInsight, with finishing touches in GIMP.

M3 is one of the brightest and largest globular clusters in the northern sky: it contains an estimated half a million stars! Located about 34,000 light-years away from Earth, M3 measures about 180 light-years across.
M3 is also scientifically significant, as it contains at least 274 variable stars (the highest number found in any globular cluster). Its estimated age is between 8 and 11.4 billion years, making it a true ancient relic of our galaxy.

M3 (2025-05-19)M3 with annotations (2025-05-19)

In the annotated version of the image you’ll also notice the faint galaxy NGC 5263, sitting approximately 240 million light-years away.

Thank you for reading this post and clear skies!

M13 (2023-05-30)

The Great Globular Cluster in Hercules in its splendor

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The Great Globular Cluster in Hercules in its splendor

Less than 1 minute Minutes

I decided to image the Great Globular Cluster in Hercules (M13) despite the presence of the bright Moon. In this article I would like to share the result of this effort, which is my best capture of M13 to date.

The sky was clear and seeing and transparency were above average. I couldn’t miss this opportunity and decided to give a try. I imaged Messier 13, the Great Globular Cluster in Hercules.

Messier 13 shines as the most remarkable globular cluster visible in the Northern Hemisphere. Situated 25,000 light years away from us, this celestial gem stretches across 145 light years and has an estimated population of 300,000 stars.

Now imagine how the sky would appear from an hypothetical planet orbiting one of the stars near the center of Messier 13. The distance from our hypothetical planet to the closest star would be about 0.05 light-year. For comparison, in our solar system, this would be inside the Oort Cloud!
Across the entire sky, inhabitants of this hypothetical planet would see 10,000 stars brighter than 1st magnitude, and more than a thousand brighter than Sirius!

Setup

Date: 2023-05-30
Location: my driveway in Richmond Hill (ON)
Scope: C8 SCT
Camera: ZWO ASI533MC PRO (cooled at -10 °C)
Filters: none
Mount: Celestron AVX
Guiding camera: ZWO ASI224MC, IR-Cut filter, PHD2
Guide Scope: Orion Deluxe Mini 50mm Guide Scope
Software: NINA, PixInsight, BlurXTerminator, NoiseXTerminator, GIMP
Total integration time: 60 minutes (30×120 seconds).
Calibration frames: 10 dark, 15 flat, 100 bias
Size: 29.7 x 29.7 arcmin
Radius: 0.350 deg
Pixel scale: 0.592 arcsec/pixel

Note: Scroll the slider to switch between the images of Messier 13 and the galaxy IC 4617 (highlighted in red) with and without annotations.

Scroll the slider to switch between the images of Messier 13 and the galaxy IC 4617 (highlighted in red) with and without annotations.Scroll the slider to switch between the images of Messier 13 and the galaxy IC 4617 (highlighted in red) with and without annotations.
I spent lot of time balancing the mount, polar alignment was very accurate, and with the optimal sky conditions, the mount was guiding almost perfectly, as you can see in this screenshot.
I spent lot of time balancing the mount, polar alignment was very accurate, and with the optimal sky conditions, the mount was guiding almost perfectly, as you can see in this screenshot.

I would like to conclude this post with a curiosity. In 1974, the Arecibo Radio Telescope in Puerto Rico sent a message towards Messier 13. The message, conceived by a team of scientists led by Frank Drake, aimed to communicate our presence and intelligence to potential extraterrestrial civilizations. Comprising a pictorial representation of our fundamental knowledge, the message contained a numerical system, atomic numbers, and the DNA structure, among other key elements. The message will take around 25,000 years to reach its destination!

The comet C/2017 K2 (PANSTARRS) and the globular cluster M10

A bright comet meets a globular cluster

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A bright comet meets a globular cluster

Less than 1 minute Minutes

A few days ago, while using my astronomy planner app (SkySafari), I noticed an interesting event on the night of July 14: the comet C/2017 K2 (PanSTARRS) and the globular cluster Messier 10 would have been in the same field of view of my refractor telescope and imaging camera. I checked the weather forecast and it was clear, so I prepared my equipment for the night and when the sky was dark enough (around 11pm EDT) I launched my routine imaging process. Due to the comet motion in the sky I had to keep the exposure time shorter than usual, so I wasn’t totally sure about the results. But looking at the final processed image, it was a success!

Until the next time, clear skies!

Setup

Scope: Explore Scientific ED80CF APO refractor
Mount: Celestron AVX mount
Imaging Camera: ZWO ASI533 MC PRO (cooled at -10°C)
Filters: Optolong L-Pro
Guiding camera: ZWO ASI224 MC with a IR Cut filter, PHD2
Guide Scope: Orion Deluxe Mini 50mm Guide Scope.
Software: NINA, PixInsight
Total Integration Time: 30 minutes (15x120s, dark, flat, bias)

July 14, 2022: the comet C/2017 K2 (PANSTARRS) shared the field of view with the globular cluster M10 in Ophiucus and I imaged them from my driveway!

The comet C/2017 K2 (PANSTARRS) and the globular cluster M10

This animation shows the motion of the comet C/2017 K2 (PANSTARRS) amid the stars in just 30 minutes!

The comet C/2017 K2 (PANSTARRS) motion on July 14, 2022