Tuesday, February 24, 2009

Comet Lulin

I was able to capture Comet Lulin in its colorful form. It is a beautiful comet that has changed its shape several times already.

This image was featured for a day on SpaceWeather.com.


Don said...


I tried to e-aml you, but mail sent to phil@visualuniverse.org is rejected.

I love your Lulin image.

I notice that you said you had LRGB = 48 minutes.

I’m wondering if you would share a few more details,

How long was each sub-frame and how many of each channel did you use?

I do some narrowband imaging myself, just hobby level stuff.


Most recent stuff is here…


I was out shooting the Rosette with a camera lens and ST10 on Saturday.

I put in 45 minutes on Lulin, because I had the opportunity, but I didn’t take any Luminance and I had to use H alpha for the red channel.

(My color filter wheel only holds 5 filters, I had Ha, SII and OIII in the first 3 slots, full spectrum blue and green in the other 2.)

Anyway, comets aren’t really my specialty but I’ve enjoyed the processing challenge and I’d like to learn more.

It appears that you probably stacked and processed the background stars and comet separately and then married the two together.

There are a couple of ways that I know of to perform that step.

I’m curious how you did that as well.

Thanks for your time and for posting your wonderful images.


VisualUniverse said...

Hi Don,

My email addr is pj@visualuniverse.org, but I have a catch-all that should have fwded your email to me. Sorry about that.

The ST-10 is an excellent camera. I have had the opportunity to borrow one on several occasions and really enjoy it.

I've been bombarded by questions asking about the processing technique. Funny thing is, on Sunday evening when I started playing with the data, I was shocked to see just how good it was, so I spent the next 5 hours working on it. At around 2:21am CST, I finally called it quits and had to be happy with the result.

Now for me to go back and reconstruct the exact steps I took at that late at night would be difficult. I was shooting at a very wide-angle, which allows for some comet movement tolerance. The core is elongated because of the movement, but I used curves to de-emphasize the core and bring out more of the tails.

I see you like narrowband imaging. Have you submitted your work on CloudyNights.com CCD thread to gain feedback?