52 replies to this topic

[cloudbuster]

Hi All,

 

During my last trip to Namibia I had the opportunity to spend 10 cloudless nights under a Bortle 1 sky (at the Rooisand Desert Ranch near Gamsberg). Of the available 105 hours of full astronomical darkness I managed to use 93 of them for observing and mostly sketching. That was more than I had hoped for!

 

For the trip I only had one goal: observe all Caldwell objects that I can't see (or hardly see) from La Palma (because I don't know if and when I'll be back in Namibia...) In practice this mean everything from Caldwell 83 and up, but because I had some more time than anticipated I could stretch it to everything from Caldwell 80.

 

It will take some time before I will finish this massive project, so I will show my progress here whenever I finish a sketch, starting with number 80, then 81 and so on until 109.

 

For observing I used two telescopes: a 12" F/4.8 dobson with very fine optics and a 16" Dieter Martini dobson with Alluna mirror. Both were built wonderfully well and were a true bliss to work with.

Here's a picture of both from my observing platform, pointing south over the beautiful landscape for another night of hard work:

 

 

 

 

Time to get started and I can't think of a better object than Caldwell 80 - NGC 5139, of course Omega Centauri! It’s incredibly massive and bright, but not really denser towards the core; the condensation is most evenly spread throughout the whole globe, only fractionally brighter in the middle. The shape is definitely oval and defined quite well near the edges. In the center I noticed two darker pockets, like eyes, with in between them a thin line of tiny stars. Up and right within the cluster a small star chain could be seen, like a short arm. A similar line was seen down and left, but outside of the cluster. On the left side of the core, a few stars in a trapezoid shape shone just a tad brighter. Beside it was one of the few double stars in a rich star field. I decided to sketch this one at the lowest magnification, to seemingly shrink the cluster to somewhat acceptible proportions… Sketched with a 16″ Dieter Martini @58x.

 

 

Edited by cloudbuster, 11 June 2022 - 01:45 PM.

[Warmvet]

Outstanding sketch and report of your adventure observing the southerns Caldwells. Bortle 1 skies will give you some pretty impressive views! Looking forward to seeing more.

 

Cindy

[Nightowl99]

Wow, what an experience! Thanks for sharing and getting us excited to see more! Great start with the stunner Omega Centauri, a treat from the globular cluster specialist.

[frank5817]

Martijn,

 

That is a very impressive sketch of Omega Centauri. I can catch it from here in Arizona, but it is close to the horizon. With it high in the sky where you were it must have been an easy naked eye target.

 

Wonderful sketch

 

Frank

[cloudbuster]

Oh yes, naked eye with ease, but not as bright as 47 Tucanae. I promise there will be much more globular clusters in this topic 

 

Here's another one:

 

NGC 6352 (C81) is not very bright and appears as a smudge of light on the first impression. But closer inspection (higher magnification) does show the graininess and an off-center core in a bit of an egg-shaped cluster. I could definitely not resolve the cluster, but some stars could be seen flickering by constantly changing the eye position a bit, up to the very core of it. The field is littered with dim stars and some star trails could be followed. One going down and left (dim) and one left of the core (brighter). A very pleasing view, despite the low brightness. Sketched with a 12″ dobson.

 

 

 

[mdowns]

This thread is a grand idea Martijn and I love the background information you've included.Your fine drawing of 5139 is like the season premier of a favorite television show,you can't wait to see the next episode.We all look forward to the Caldwells to follow!

[BQ Octantis]

Wonderful!

 

I visited all the southern Caldwell objects with my C5 f/6 and a 15mm SWA EP (2.5mm exit pupil) when I first moved to the middle of the Australian Outback. But I wish I'd had your light buckets!

 

BQ

Edited by BQ Octantis, 11 June 2022 - 02:34 PM.

[Astro-Master]

Great sketch of 5139, sounds like your trip was a dream come true!  Looking forward to your sketch of 47 Tucanae.

[bphaneuf]

Fabulous trip Martijn!  The sketches you've posted really build anticipation for the next ones to follow.  Globular cluster specialist, indeed!

-b

[astronz59]

Martijn, your sketches have captured these amazing objects perfectly. I don't see as many field stars as you did, but both are great subjects to sketch and marvel at!  

[cloudbuster]

NGC 6193 (C82) was a bit of a deception. I was expecting an open cluster, but not much stars could be seen, besides a small grouping in the centre. However, I did see some nebulosity... is this the reason this object was selected for the Caldwell list? Not sure. Applying an OIII filter shows the nebulosity better, especially on the left side where I see a line as a "ridge" with left of it a pitch dark sky background. On two areas this line appears brighter and on the top left the "wall" bends to the left and out of the field of view. To the right of this brighter line, a veil of nebulosity in triangle shape can be seen, as a "cape". The OIII filter dims many of the stars of the cluster to beyond visibility, so I decided to switch to UHC to get the best of both worlds: some nebulosity and most of the stars of the cluster. My conclusion is that the nebulosity is an interesting feature, but the cluster itself by no means is...

 

[Starman47]

Nice sketches. Looking forward to more.

[mdowns]

Martijn your comment "My conclusion is that the nebulosity is an interesting feature, but the cluster itself by no means is..." matches very well my view of both from here.You did however, pick up many more fainter field stars than I can see.Some objects lack visual appeal but finding and drawing them is still fun for sure.Another Caldwell down,I'm with Starman47 and am looking forward to the next.

[Nightowl99]

The cluster itself may have been underwhelming but the sketch of it is simply beautiful. The faint nebulosity is sharply contrasted because of the ridge and wall you describe and the cape draped across the cluster with a beautiful collection of field stars makes this view so nice sitting at home in front of my computer. Well done! 

[nof]

Cloudbuster, This is an ambitious project, looking forward to seeing it unfold. The sketches are magnificent! You must have sketched all these objects when you could see them, so are you reworking and finishing the sketches now one-by-one?

[cloudbuster]

Thank you all for your kind words 

 

@nof: indeed, all the sketches that I did behind the eyepiece are finished (I kept them close in my backpack as handluggage, because I was too afraid that something would go wrong carrying them as checked luggage and lose all the work...). Now I'm reworking them to digital versions like I always do. It takes time, I can do 1 or max 2 on an evening, depending on the type of object and on the amount of time that I have.

 

Today I have NGC 4945 (C83), the “Gold Dollar Galaxy” for you. It's a large edge-on (but not terribly bright) with some interesting features. First of all, the core zone appears to be missing. Instead, a brighter area is observed just above and right of it. Another brighter zone is a line under and left on the edge. The second nickname of this object is the "Tweezers Galaxy" because of these two brighter zones and I can definitely relate to that. Above and left a bright star is seen, close to the edge where the galaxy is intruded, as if the star is somehow responsible for that… Right of it a small brighter knot can be seen. With AV, the galaxy extends much further and the field is littered with stars, too many to draw them all. This may be the most beautiful galaxy which us northerners can’t see. Sketched with the 16″ Dieter Martini dobson @129x.

 

Like always: the sketches are best viewed in the dark. During daytime there is not much to see, especially when it's sunny.

 

 

 

 

Edited by cloudbuster, 13 June 2022 - 09:06 AM.

[mdowns]

One of my favorites even here.It's striking to me how much richer the field of surrounding stars is from Namibia and of course the internal structure.I can mostly,only guess from here,what you clearly defined as lights and darks in this splendid rendering.Outstanding piece!

[niteskystargazer]

Martijn,

 

Very nice sketches  .

 

CDS,KLU,

 

 ,

 

Tom

[bphaneuf]

Great capture and sketch of 4985.  Love the labels!  It's really the next best thing to being in your eyepiece.  Even though I've not seen this object, I've seen similar characteristics in others, so those labels help me replicate the experience vicariously.  Well done, sir!

-b

[Starman47]

Nice

[nof]

Martin, why and how do you “rework “ the sketches digitally?
A nice Galaxy you have there…

[cloudbuster]

nof, as to the "why": I think my digitally processed end result matches the eyepiece view in the best way and that is always my goal with sketching. I feel much more comfortable drawing on a computer screen. Besides, the field version really is a mess with numbered stars (for brightness), lots of comments and separate small drawings.

 

As to the "how", I use GIMP for sketching. It's similar to Photoshop, but it's free to use. I have a template with exactly the same size as the circle on my field sketch paper, so that the positions of the stars and size of the object will match exactly and will not be altered during the transfer.  

 

 

Today I will show NGC 5286 (C84), again a globular cluster of which a lot more will follow...It's a beautiful cluster, but I think often overlooked because of nearby Omega Centauri, which gets all the attention. It’s definitely worth a visit because it’s bright, reasonably sized and the grainy texture is well visible. Moreover, a very bright orange/yellow star sits just beside it (m Centauri, m4.8). This makes the eyepiece view very appealing. The globular cluster is slightly flattened and gives that impression even more because of a line of stars at the underside of it. There are no obvious starchains, but I could easily resolve a single star above and right of the core. Randomly in and around the globe some dimmer stars can be seen flashing up while moving the eye around. Sketched with the 16" Dieter Martini dobson @258x

 

click for full resolution:

 

Edited by cloudbuster, 14 June 2022 - 05:30 AM.

[nof]

Thanks for another great sketch and your explanation

[cloudbuster]

IC 5286 (C85) is the Omicron Velorum Cluster. Very large and it just fits the field by use of the Nagler 31T5. It's a poor and loose cluster, if you can really call it a cluster because it looks more as an asterism to me... The center is the poorest area, but around the edges there are some very bright (blue) stars. Between all the blue and white, I could discover 1 orange star (can you find it?)

 

 

[cloudbuster]

Two new globular clusters to add to the list:

 

NGC 6397 (C86) is again a beautiful one. It’s bright and many starchains can be followed in the full field of view. The cluster is very loose, with only the heart of the core being unresolvable. Around the core about a dozen pretty bright stars can be seen floating and because of that I had at times more the feeling of looking at an open cluster instead of a globular one. The glow appears perfectly round, more so because it’s bordered by a “half pipe” of dim stars at the underside. Most noticeable is a “bar” of stars crossing the core, a bit like we see in M4 (but less spectacular).

 

 

 

NGC1261 (C87) was a deception. Of all the objects that I observed on the southern hemisphere, this was the one with the least favourable position in the sky. I had to wait until 5:30 am until it reached a mere 25 degrees above the horizon. And it showed. I chose a 10mm eyepiece to still get a decent view, but because of that the cluster remains quite small. I do see a grainy glow, which is a bit "shaved" at the underside. On the right side I see a small bulge of dim stars. This one needs a revisit when it’s higher in the sky (and when I’m less tired after a night of hard work…)