M3 RGB and CMD

[FraserClarke]

Finally got round to processing some data on the globular M3 taken 18 months ago. I think there are about 5--6 hours in B, V (equivalent to "G") and R. Makes a nice colour image (no luminosity here, just RGB), though the image quality is not fantastic (~3-4") due to poor tracking of the telescope (16-inch LX200).

Also attached is a colour-magnitude diagram made from the data. This plot shows the brightness of each star against its colour (B-V). The horizontal branch stands out nicely at B~16.3 -- these are the stars you can see as blue coloured in the image. They're hotter (i.e. bluer) than other stars of that magnitude, as they have moved past the red giant phase and are now burning Helium in there cores (for which they need to be hotter). Most of these stars are RR Lyrae variables. They make a fantastic movie blinking on and off over the course of a night. I'll see if I can work out how to post that too...

Alas, the bright sky from the centre of Oxford means we can't get good enough photometry down to B~21, which is needed to see clearly the main-sequence turn-off in this cluster I think you can make it out if you know what you're looking for (the slight kink to the right, at about B~20)

Anyways, hope you like the picture

Fraser

[Spikey]

The kink is definately in there and it's a good graph for the conditions.

[Cath]

Nice image Fraser! .. Nice magnitude plot too!

Their is flat topping (saturation) in the image (as you know), especially in the center ...

http://www.youtube.com/watch?v=1EquUKpmxWs

[FraserClarke]

Thanks Cath. That's an interesting representation of the data! What software did you use?

Yes, the core is saturated. The bulk of that is my inexperience of making the image and not stretching it properly. The core is saturated in the raw data though, as the goal was to push as faint as possible so the individual subs are quite long. I do have some short images for the brighter stars, but I haven't merged them in.

Need lots more practice making data look pretty

[Cath]

Your WAY more experienced than me when it comes to astro image processing, don't worry

I'm just writing some simple software for myself to let me write some astro image algorithms, I wasn't going to send it out on the net but people seem to be interested in what I'm using. It's VERY basic, may or may not work on your PC as it's only really for my own testing, but here it is (WINDOWS ONLY btw) ..

Test Tool

[Cath]

hmmmmm, the forum software doesn't like back slashes rather than forward slashes .. try again ..

Test Tool