Archive for May 2021

Globular Cluster, M3, NGC 5272 in Canes Venatici: May 2021 Observer’s Challenge Report #148

May 19, 2021


Compiled by:

Roger Ivester, North Carolina


Sue French, New York

May 2021

Report #148

Messier 3 (NGC 5272), Globular Cluster in Canes Venatici

Sharing Observations and Bringing Amateur Astronomers Together


This month’s target

Charles Messier discovered M3 on 3 May 1764 with a 3.5-inch refractor. The French text of Messier’s catalog in the Connaissance des Temps translates into English as: “Nebula discovered between the Herdsman and one of the Hunting Dogs of Hevelius; it does not contain a star, the center is brilliant & its light imperceptibly fades, it is round; when the sky is good, one can see it with a refractor of one foot [at the time, telescopes were generally described by their length]; it is reported on the Chart of the Comet observed in 1779. Mémoires de l’Académie of the same year. Reexamined 29 March 1781, still very beautiful.”

According to William H. Harris’ Catalog Of Parameters For Milky Way Globular Clusters, , M3 resides 10.2 kiloparsecs (~33,000 light-years) away from us and 12.0 kiloparsecs (~39,000 light-years) from the galactic center. It shines with an integrated V-magnitude of 6.19, and the spectral type of the integrated cluster light is F6. Does its color look slightly yellow to you?

May 2021 Observer’s Challenge Complete Report: may-2021-observers-challenge-_m3-2

Mario Motta: Observer from Massachusetts

My previous M3 was from 2013 (second photo) which I retook some frames, and reprocessed my old, better image I think with stars separated to the center, but Roger Ivester, your “dark lane” is now gone, overwhelmed by many more stars.

(The dark lane in the second photo which we have discussed earlier, is not visible in the following photo.)

April is generally a bad month in Massachusetts, with plenty of rain. No good weather this week, then the moon will be around. So, here is an image taken of M3, six years ago in color.

My 32-inch telescope, with my older SBIG STL1001E camera, RGB filters. About 1.5 hours totaling my older subs on file.

Note the dark lane on the SE in the following image which was referred to or referenced above.

Roger Ivester: Observer from North Carolina

M3 (NGC 5272) globular cluster in Canes Venatici 

Date: March 2021 

Telescope:  10-inch f/4.5 reflector

Eyepiece:  20mm + 2.8x Barlow 

Sketch magnification 160x

Field of View:  0.38º 

80mm refractor:  Little or no resolution, appearing mostly round with an intense core, and a fainter enveloping halo.  

10-inch reflector at 160x:  Excellent resolve of stars, mostly round, and with a large number of outlier stars beyond the halo.  A very interesting dark lane was noted in the SE-NE of the cluster.  

NGC 4565 via 32-Inch Telescope: By Guest Host, Mario Motta

May 19, 2021

The APOD image today is NGC 4565, an incredible image from the CFH telescope on Mauna Kea (An 8.0 meter mirror, one of the largest scopes in the world), see the image at the bottom of this email.

Not the same level of fine detail of course (I am “only 0.8 meter” in size or 32-inches) but, it does compare nicely. I am pleased. It’s great when you can compare your image with a major “professional” telescope, for sure!

For a comparison, I’ve posted both images together: Roger

I’m especially happy that the color is almost a match, as I’m a stickler to “get the color right”, and based on the professional image, I think I achieved this.

Much of this is not only “just good” optics, but good processing.

Despite imaging since the 1980’s I am still learning, and have adopted some recent techniques in PixInsight which helped get the color exactly correct, and squeeze out good detail.

Speaking of the CFH (Canada-France-Hawaii) telescope, I visited the facility some years ago, its mirror was cast in the Arizona mirror lab by Roger Angel who perfected the technique of casting and polishing these behemoth mirrors.

One of his mirror makers, Peter Wangness left the lab to set up his own private mirror making commercial business. He says I was his first customer, when he cast my 32-inch (0.8 meter) scope as a favor, and at cost as a test back in 2004. He pre-made the rough curve before I ground and polished it.

To minimize cost and engineering, he simply took the plans of the 8 meter mirror and shrunk it down to 0.8 meter…so my 32-inch is in effect a “1/10th” model of the CFH telescope. Something I have always been very happy about.

For all reading this: you can now compare directly an image from the 8 meter CFH, and its 1/10 scaled model…which is my scope.

Mario Motta