An In-Depth Study of NGC 6633 with 15×70 Binoculars

Time: 2.5 hours, ~12:30am to 3:05am CDT (~05:30-08:05 UTC)
Date: June 16th, 2018
Light pollution: Bortle 3 to 4
Seeing: Alright
Transparency: Very Good
Instrument: Oberwerk 15×70 Ultra binoculars, mounted on my homemade parallelogram mount


NGC 6633, sketched over the course of 3 hours in the early hours of the morning on June 16th. Mounted Oberwerk 15×70 Ultra binoculars, regular pencil on sketchbook paper.


The following is a transcript of a voice recording begun at 3:04:42am CDT, Saturday, June 16th, 2018. I was using 15×70 Oberwerk Ultra binoculars mounted on my newly-functional parallelogram binocular mount, and observing from a balcony in Jasper, AR (Bortle 3 to 4). The seeing was alright, the transparency was very good, and the moon was not up.

“Observed and sketched NGC 6633 with 15×70 Oberwerk Ultra binoculars on my very awesome homemade parallelogram binocular mount. This remains one of my favorite objects. [chuckles] After my thorough study of this month I might be able to stand not looking at it as often, honestly, but still— ok, is it already twilight? Because it’s getting brighter out here. Surely twilight doesn’t start at three.


It’s a nice size in the binoculars, medium- it’s just small enough that you get a framing of the field around it, and you can take it all in at once, but it’s large enough that you can clearly see the details; and in fact, I like this size best for seeing the asterism. The- at the moment- lower portion of the cluster is a sort of a triangle with rounded corners, with a single star sitting in the center, otherwise an empty center. Each corner of the triangle has at least two stars, two of the corners have four stars, so it’s a well-defined triangle. Coming off of the tip, arcing at first a little bit towards the left and then back up and towards the right, are two main star trails, and a third begins about halfway up. They all end at the same point- or, not the same point- they all end at the same distance; and they are all pretty much parallel, but spreading out slowly until the end, where they end at their brightest.

The asterism looks like that of a cartoony shooting star. The triangle on the bottom being the star shape, and then the three arcing lines coming out of the top are the trail that you see behind the clip-art shooting stars, that kind of thing. I very much like this asterism. You can also see- and actually, right now happens to be when it’s just about exactly correct-image- an asterism which shows it as being the shape of Italy. Now the bottom is the bottom of the boot, the top is the top of the boot, and there’s an additional enhancement to the starfield; not a physical part of the cluster I don’t believe, off to the lower left of the boot, and it’s somewhat triangularly shaped, in the shape of Sicily. What I see when I look at it is the shooting star, but when I think about the Italy asterism I can make myself see that pretty easily in these binoculars. Not so much in the telescope.

A dark nebula is visible to the left of the cluster in the FOV. It’s not extremely obvious; it was only after studying the field for so long that I came to realize it was there. It’s large, has an opacity of maybe 2 or 3. Lots of stars are still visible silhouetted on it, but it has noticeably fewer faint background stars than the rest of the field. And, if you go to the other side of that dark nebula and then up a little bit, you come to IC 4756! I like this one too. I still remember the excitement of finding it for the first time in the 8″ in Grandma’s backyard… [chuckle] and then not being able to find it any other time I went looking, but it was cool that one time! Here it’s obvious. It’s a clear enhancement in the field, a congregation of stars somewhat off-center. It’s like something…. flying. You have the body in the upper left, it’s just a great density of stars, and then marked by brighter but sparser stars on the left and right you have wings, and on the bottom a tail, so it’s like a bird in flight. There’s even a little stellar enhancement farther to the left than that which it looks like it might be chasing. Perhaps it’s a hunting bird. The cluster itself, quite well separated from the background, as is NGC 6633. It’s not quite as well separated as 6633, because overall it’s medium to medium-faint whereas 6633 is medium to medium-bright. 6633 is very obviously separated, where 4756 is also very obviously separated, but not to the same degree. Either of them would be easily picked up in a sweep; let’s put it that way.

Both are visible to the naked eye; 6633 more easily, 4756 takes a little bit of strain. And that dark nebula in the middle is actually visible, now that I look at it, as a notch in between 6633 and 4756, reaching up from the bottom. With the naked eye 6633 is noticeably smaller and brighter than 4756, which looks like kind of just a prong on the Milky Way.


Ok. That sketch took a while. Three hours, ish? Some of that time was spent finding the screwdriver to resecure the binoculars after they clocked me over the head.”

Clear Skies!
Lauren Herrington

One Response to An In-Depth Study of NGC 6633 with 15×70 Binoculars

  1. EdF June 30, 2018 at 10:36 pm #

    I had to make my observation 6633 from a very light polluted spot with a street light about 25 yards away. After reading your transcript I hope to be able to get to a dark sky and repeat the observation. Having a good description of what is in the field of view really helps to bring out the hidden treasures,

    Thanks for the time you spent on this object

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