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The Sun is in an area crisscrossed by minor spurs connecting the arms (I think Gaia DR4 will give us a detailed map) but perhaps not exactly in an arm.

Made another slight change to the analog image to make it fit the Milky Way model.

I still might tweak my model to extend the Centaurus arm. Some astronomers write about an "Outer Scutum-Centaurus arm". No doubt there are star formation regions in the far outer galaxy but do they really form a visible arm? I don't see that in the data but could be convinced.

And third, just for fun, here is the above model overlaid on top of the famous 1958 Oort radio hydrogen map of the Milky Way.

Second, a revised version of my analog image. This takes an image of NGC 2336, which closely resembles the Milky Way, and tweaks it so that it follows the model even more closely.

After yesterday's huge threads about my first quadrant map, I'll be quieter today. But here are some images based on the same data sets. First, a new model of the Milky Way with ring arms based on the same data sets.

Note that the Oort 1958 image used the old system of galactic coordinates.

... better than we sometimes give them credit for or, to put it another way. not as much has changed in astronomy as we sometimes believe.

If I overlay the spiral model I derived from the recent data sets I've been using over the famous Oort 1958 map of the Milky Way, I see what appears to be a pretty close match. I don't want to overemphasize the significance of that other than to point out that the golden age cartographers were ...

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An important point is that all of the Milky Way spiral arms (however you count them) are different, from the flamboyant Centaurus arm to the unpredictable and flocculent Perseus / Norma arm.

I've been working on the map of the Milky Way first quadrant I released today for quite a while and I used it previously to modify the Milky Way analog NGC 2336 to create this new image of the Milky Way.

Flocculence is one of the reasons (beyond problems with velocity distance estimation) why there are still and possibly will always be questions about any map of the first quadrant. It is useful to have a map, but ... is it the correct map? Could there even *be* a correct map? 🤔

... we also see it for the Kwee arm and even to some extent for the Cygnus arm. In their recent 2025 paper "The Flocculent Structure of the Inner Milky Way Disk", Balser and Burton point out that this is also true for atomic hydrogen. ui.adsabs.harvard.edu/abs/2025AJ.....

One of the features of the first quadrant is the flocculent nature of the arms. There is material not only in the arms, but *between* the arms as well. This is not surprising for the Centaurus and Carina arms as they merge together when they enter the inner galaxy. However ...

If you look carefully you can even see these fingers in Gaia maps. There are ways to hide them like jittering galactic longitude randomly but it is important to see all the limitations of this map.

You'll notice that the Hi-GAL dust map (in orange) is divided into mostly short segments that all point *exactly* at the Sun. Astronomers often jokingly call this the "finger of god" effect and it is caused by distance estimate errors that extend these segments in the line of sight.

I needed a name for this arm and since Kiem Keng Kwee, a student at the Leiden Observatory in the 1950s, was the lead author of the discovery paper, I decided to use his name on the map.

However, if I overlay the Kwee figure on my map, I see that that the inner Kwee segment covers *both* the Carina and Centaurus arms as they merge together in the inner galaxy. The outer Kwee segment is a separate non-optically visible arm. In fact it is one of the arms that forms the inner ring.

These spiral segments were never given names because it was assumed that they were extensions of known optically visible spiral segments. I would call these optical segments the Carina and Centaurus arms but they have had many other names as well such as the Sagittarius and Scutum segments.