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Just another observation of M4

Dob Observing Report
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#1 azarquiel.2001



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Posted 01 July 2022 - 06:27 AM

Hi all!

A new object report from my last getaway just one week ago. As usual, if you prefer to read it in PDF format with the support of some images that helps me to explain better myself you can check it in the web:




Please take into account those images are pictures not sketches. As you can read in my web they have been gathered from public databases, mainly from telescopes in Palomar Mountain, HST and Calar Alto (Spain). What I have tried (quite successfully, I think) is to reflect how the object shifts with the change of eyepieces. The images can become a composite of several to show a better result. Also I have added a fixed rectangle to show the effect of the apparent field of the eyepiece. I play a little bit with the brightness and contrast to show how your eyepiece field is darker at lower eye pupil, but you lose details in the object. I mean, if you try to find exactly the same picture in the web you are going to fail. It takes a couple of hours (sometimes more) to generate all the pictures to get the better result, plus an extra hour to write down my voice-notes.


Nagler 31mm (70x - 1º 10’ - 6.6mm).  How beautiful M4 looks with large apertures! It has always looked interesting when I have seen this object with other apertures (smaller than 10") but without being able to get much detail out of it. Like a very faint open cluster from which one sensed a subtle beauty but with the impression that I could get more of it if I had more aperture. This is the case. The object changes a lot with this telescope. Even with the 31mm it takes up much of the eyepiece field, I think more than a fifth of the entire field Despite being an open cluster it has a very beautiful shape because it is very balanced and, even having stars of different magnitudes, there is not so much variation between them. And as the object is composed by hundreds of stars the details are multiplied throughout it. I am struck by a kind of straight line of stars with higher brightness that runs through the core of the object from north to south. To the right of this line (in my eyepiece) there is a sort of grouping of stars forming a Y, and above it and the line of stars in the center there is a pair of brighter stars of a reddish color that also captures my attention. Moving on to look at the outermost part of the object I am attracted to the sort of ‘arcs’ of stars I see at both 7 and 5 o'clock. Most of the stars have a cool, white or blue hue with a few exceptions of a slightly redder color.


Nagler 22mm (98x - 50’ - 4.7mm).  What a spectacle! The object increases its beauty and  also the difference between the magnitude of the stars is increased. The center of the object continues to attract my attention with this row of stars running along its entire length. The two pale red stars at 1 o'clock are very beautiful, submerged among so many white/blue stars. Also very striking, is the large number of stars that can be resolved. The cluster does not look like an undefined gray cloud that sometimes accompanies open clusters. On the contrary, a multitude of stars can be defined on everywhere, as very faint but independent points. That view gives the whole a beautiful and charming appearance. They say that beauty is in the symmetrical proportion, probably that is happening to me with this object, the number of stars, their distribution and balance in the different magnitudes makes the object beautiful, plain and simple beautiful. It is a pleasure to spend the minutes contemplating each star individually, seeing how it is part of this set. It is difficult to explain the pleasure that produces this feeling of beauty to be contemplating an object so easily resolvable while showing a clear structure of the whole.

A beautiful image with the 22mm.




Delos 14mm (154x - 28’ - 3mm). Woooow what a beauty! I lose a bit of color in the stars, they all pale equally and appear more homogeneous in color, but in turn more and more individual stars of lower magnitude are resolved. Also this eyepiece has 72º of apparent field and that encloses the object making the impact on your mind even greater as all your attention is focused only on the object itself. It is the center of the object that captures your attention the most but it is worth looking at the outermost stars and the arcs they form. In particular in the 8-9 o'clock region I see a couple of very beautiful concentric arcs of stars, also a branch of stars coming out from the innermost part of the cluster, at about 7 o'clock, making a kind of hook. And in the 5 o'clock area there is also another arc of stars clearly separated from the more central region of the open cluster. It is a pleasure to enjoy this spectacle.


Ethos 10mm (216x - 27’ - 2.1mm). Although with the 10mm the image is even larger and the details are easier to see, the reality is that I don't get much more than I had enjoyed with the 14mm. It is much more pleasurable to observe with 100º of apparent field and I think the stars look a bit brighter and more punctual although maybe it is suggestion. In any case I think M4 is going to become my favorite open cluster and the image offered by ALL eyepieces is captivatingly beautiful.



Ethos 8mm (270x -  22’ - 1.7mm).  This eyepiece does bring me new impressions. First, the central line now appears ‘broken', disconnected between the northernmost part where several stars of the same magnitude are seen, and the southernmost part. In the center of the line, stars of similar magnitude to the rest are seen and therefore the line appears to be broken. The famous Y of the 3 o'clock region in the central part gains prominence and now it reminds me more of a tilted V. The contrast I am gaining in the object object is more and more striking. It impresses me because gives me the sensation of seeing the stars brighter than before, as if I were gaining light instead of losing it (which is absurd). But this is how my brain tricks me by gaining contrast. The space between the stars also increases. As in many occasions I have the feeling that the object has changed with respect to what I saw at low magnifications. Obviously it is still M4, and it is still an open cluster but now I am so focused on the center of it that it is difficult to pay attention to the outer parts. A marvel.




Delos 4.5mm (480x - 9’ - 1mm). I think I'm overdoing the magnification here. Although this eyepiece allows me to quietly enjoy the inner parts of M4, it doesn't captivate me as with the first eyepieces (or even the 10mm). I still enjoy that row of stars now totally broken in its central part, and what catches me the most is the famous Y transformed into V that now seems to me a small reflection of the constellation Taurus. I will highlight it with a drawing. The focus of the stars is also very complex with this eyepiece and makes the object loses some of its beauty by not being able to see point stars. It is also true that the object has long since passed its meridian and therefore is already approaching the horizon adding layers of atmosphere between its light and my telescope. However, it was worth going up to these magnifications to have a different vision of it.

M4, a beautiful open cluster.




Dark and clear skies!

  • Dave Mitsky, jim kuhns, BrentKnight and 4 others like this

#2 Epick Crom

Epick Crom

    Ranger 4

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Posted 01 July 2022 - 07:06 AM

Fantastic report Israel. It seems like you are having the time of your life with your huge scope! That bar feature across the face on M4 is unique. Wishing you clear skies.

  • azarquiel.2001 likes this

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