Placidus
14-06-2017, 01:16 PM
Omega just about overflows our field of view, so here be a 9 panel mosaic.
The full size image (https://photos.smugmug.com/Category/Clusters/i-Z4HpCHw/0/02d64341/O/Omega%20Centauri%20Annotated.jpg) (7000 pixels/side) is about 6 MB.
A smaller version is here. (https://photos.smugmug.com/Category/Clusters/i-Z4HpCHw/0/02d64341/4K/Omega%20Centauri%20Annotated-4K.jpg)
The thumbnail is a tight crop of a representative patch.
We've had two goals here. An easy one is to make the cluster stand out from the background, high contrast and sharp (without overdoing the sharpening), so we've gone easy on stretching. The background is stretched about 200 times compared with a raw sub.
The second goal was to show the colour how we think it should be. We are motivated by NASA's Hubble close-up (https://www.nasa.gov/mission_pages/hubble/multimedia/ero/ero_omega_centauri.html), where they show the majority of stars in the cluster as yellow-white.
As mentioned elsewhere, we're very aware that this is a fairly old, seniors-card carrying, zimmer-frame pushing member of our galaxy. Consequently most of the stars are older than the sun. When we look at it visually, it is a warm colour, certainly not blue-white.
We've annotated the spectral types of a few of the brighter stars, and, keeping in mind that anything in Centaurus is reddened by dust (see NGC 4945 for example), and we want it to stay that way, we've made the G0 star close in at about 8 o'clock be a yellow-white. The smattering of A0 and A5 stars scattered about the image are by comparison very blue-white.
A close look at the core shows that as well as the overwhelming orange-yellow stars, there is a heavy sprinkling of blue stragglers.
There is an edge-on spiral toward the top left corner, but not much else in the way of galaxies, as befits the somewhat dusty location.
North is up. The field is about 1.08 degrees across, at 0.55 sec arc/pixel.
72 ten minute subs (12 hours total). Aspen CG16M on 20" PlaneWave. Taken mostly under full moon. Processing with GoodLook 64.
Very best,
Mike and Trish
The full size image (https://photos.smugmug.com/Category/Clusters/i-Z4HpCHw/0/02d64341/O/Omega%20Centauri%20Annotated.jpg) (7000 pixels/side) is about 6 MB.
A smaller version is here. (https://photos.smugmug.com/Category/Clusters/i-Z4HpCHw/0/02d64341/4K/Omega%20Centauri%20Annotated-4K.jpg)
The thumbnail is a tight crop of a representative patch.
We've had two goals here. An easy one is to make the cluster stand out from the background, high contrast and sharp (without overdoing the sharpening), so we've gone easy on stretching. The background is stretched about 200 times compared with a raw sub.
The second goal was to show the colour how we think it should be. We are motivated by NASA's Hubble close-up (https://www.nasa.gov/mission_pages/hubble/multimedia/ero/ero_omega_centauri.html), where they show the majority of stars in the cluster as yellow-white.
As mentioned elsewhere, we're very aware that this is a fairly old, seniors-card carrying, zimmer-frame pushing member of our galaxy. Consequently most of the stars are older than the sun. When we look at it visually, it is a warm colour, certainly not blue-white.
We've annotated the spectral types of a few of the brighter stars, and, keeping in mind that anything in Centaurus is reddened by dust (see NGC 4945 for example), and we want it to stay that way, we've made the G0 star close in at about 8 o'clock be a yellow-white. The smattering of A0 and A5 stars scattered about the image are by comparison very blue-white.
A close look at the core shows that as well as the overwhelming orange-yellow stars, there is a heavy sprinkling of blue stragglers.
There is an edge-on spiral toward the top left corner, but not much else in the way of galaxies, as befits the somewhat dusty location.
North is up. The field is about 1.08 degrees across, at 0.55 sec arc/pixel.
72 ten minute subs (12 hours total). Aspen CG16M on 20" PlaneWave. Taken mostly under full moon. Processing with GoodLook 64.
Very best,
Mike and Trish