UK-1 faintest globular known imaged in near infrared.

[sjastro]

It's quite extraordinary how the NIR filter digs this object out of the field.
The object is invisible in the combined R, G, B exposures.

Getting the colour balance right when using conventional RGB filters instead of the NIR variants proved to be quite a challenge.

http://users.westconnect.com.au/~sjastro/uks1c.html

Clear skies

Steven

[Stevec35 (Steve)]

Nice shot Steven. I see you've picked up VVV CL001 too at the top right.

Cheers

Steve

[dvj (John)]

Wow, nice one! first ever image i've seen of this.

[RickS (Rick)]

What a cute little critter!

[SkyViking (Rolf)]

Great image of this faint globular, and you bagged Steve's cluster too, nice work!
So is this a NIR-RGB image?

[davewaldo]

Very cool image. I love these little know objects.

Can anyone else see a faint blue line almost through the middle? Satellite in the blue channel?

[sjastro]

Originally Posted by Stevec35

Nice shot Steven. I see you've picked up VVV CL001 too at the top right.

Cheers

Steve

Thanks Steve.
I kept an eye out for your globular. It's easy to spot knowing where to look. I doubt I would have noticed it otherwise, as it doesn't exactly leap out at you.

Originally Posted by dvj

Wow, nice one! first ever image i've seen of this.

Thanks John.

Originally Posted by RickS

What a cute little critter!

Interesting you should comment about it's size Rick. The globular has a reported apparent diameter of 18.8 arcminutes yet it appears much smaller in the image which is presented at 80% resolution.

Originally Posted by SkyViking

Great image of this faint globular, and you bagged Steve's cluster too, nice work!
So is this a NIR-RGB image?

Thanks Rolf.
It is a NIR-RGB image. While the star colours are preserved the globular itself turned out to looking almost monochrome. I had to select the globular and stretch out the red channel level in Photoshop to indicate the considerable absorption the object exhibits.

Originally Posted by davewaldo

Very cool image. I love these little know objects.

Can anyone else see a faint blue line almost through the middle? Satellite in the blue channel?

Thanks Dave.
It is a satellite trail in one of the 10 minute B exposures. I thought it was dim enough not to be noticeable. I might go back and sigma combine the colour images to get rid of the trail.

Clear skies

Steven

[John Hothersall]

I was amazed how this showed up in IR V red. Individual stars show well in the cluster, you could combine IR R G as RGB mapped.

John.

[sjastro]

Originally Posted by John Hothersall

I was amazed how this showed up in IR V red. Individual stars show well in the cluster, you could combine IR R G as RGB mapped.

John.

Hello John.

You mean IRGB with the NIR data mapped to the red channel?

Regards

Steven

[Terry B]

Originally Posted by sjastro

Thanks Rolf.
It is a NIR-RGB image. While the star colours are preserved the globular itself turned out to looking almost monochrome. I had to select the globular and stretch out the red channel level in Photoshop to indicate the considerable absorption the object exhibits.



Steven

This makes sense as you stated that it wasn't visible in the colour images. This means that there is no colour data to add for the cluster. Maybe it should be left as monochrome or fudge it by moving all the colours 1 colour to the red. ie use the BGR channels on GRI and don't use the B filter at all. Still use the I filter as the lum though.

[Ross G]

An amazing capture Steve.

Ross.

[sjastro]

Originally Posted by Ross G

An amazing capture Steve.

Ross.

Thanks Ross.

Originally Posted by Terry B

This makes sense as you stated that it wasn't visible in the colour images. This means that there is no colour data to add for the cluster. Maybe it should be left as monochrome or fudge it by moving all the colours 1 colour to the red. ie use the BGR channels on GRI and don't use the B filter at all. Still use the I filter as the lum though.

The technique I use is similar to enhancing Ha detail in galaxies without resorting to using a Ha filter.
Is there a rationale behind the mapping procedure, or is it a trial and error exercise?

Clear skies

Steven

[John Hothersall]

Steven I mean IR to red channel, red to green chan and green to blue chan. I tried it with one of my Terzans in IR and it turned out with a greenish tinge but was less noisy and needed rebalancing hue+colour. You can blend IRGB with RGB and results are better. You have plenty of good data to play with on cloudy nights.

When I imaged it I had no response in the RGB but with IR it just leaps into full view.

John.

[sjastro]

Thanks for the info John.

Clear skies

Steven