Disturbed Galaxy NGC 3521 in Leo

PhotonCollector (Paul) · #1 17-04-2006, 11:22 AM

Geeday everyone,

Here's an image I did of a very interesting galaxy, NGC 3521 in Leo.

It's 7 x 4 minutes exposures @ ISO-200 with the modified Canon 300D on the 12-inch f/5 GSO telescope using the Baader Coma Corrector - handguided with 4.5" guidescope. Images are dark-subtracted, flat fielded, offset adjusted, with IRIS. Image is masked in PS.

There's a higher resolution image here
http://www.skylab.com.au/pmsa/NGC%203521.html

Paul M

Itchy · #2 17-04-2006, 01:46 PM

Hi Paul

A very interesting galaxy indeed.

On my monitor I detect a fair degree of horizontal banding on this image. Possibly pattern noise. Do you see it too?

Cheers

tornado33 · #3 17-04-2006, 03:29 PM

Nice shot, I dont remember seeing that galaxy before, I wonder if there are many HST or observatory shots of it. Theres a lot of detail in the disk there.
Scott

PhotonCollector (Paul) · #4 17-04-2006, 03:45 PM

Quote:

Originally Posted by Itchy

Hi Paul

A very interesting galaxy indeed.

On my monitor I detect a fair degree of horizontal banding on this image. Possibly pattern noise. Do you see it too?

Cheers

Hi Itchy,

Yes your right. I have only seen it since I switched to my LCD display. On my monitor the bands were barely noticeable, if at all.

It appears I get banding in the images with the signal to noise ratio of individual exposures is too low. - I think.

So does this mean I should be throwing away my old 19-inch Monitor in preference for my LCD screen?

Paul

EzyStyles (Eric) · #5 17-04-2006, 05:02 PM

beautifully done paul. very nice indeed.

Itchy · #6 17-04-2006, 09:14 PM

Quote:

Originally Posted by PhotonCollector

Hi Itchy,

Yes your right. I have only seen it since I switched to my LCD display. On my monitor the bands were barely noticeable, if at all.

It appears I get banding in the images with the signal to noise ratio of individual exposures is too low. - I think.

So does this mean I should be throwing away my old 19-inch Monitor in preference for my LCD screen?

Paul

Hi Paul

I was having similar problems with my monitor. Although I tried various tools to calibrate it, it was still too dark. A different issue (gaming I think) prompted me to update my video card driver. Once I did that, my monitor's performance dramatically improved and I was able to succesfully calibrate it to see the fainter stuff.

Just a thought rather than throwing it out.

I don't really like LCD for astro images, but some of the new ones I have seen lately may change my mind.

Cheers

PhotonCollector (Paul) · #7 19-04-2006, 10:31 AM

Quote:

Originally Posted by Itchy

Hi Paul

I was having similar problems with my monitor. Although I tried various tools to calibrate it, it was still too dark. A different issue (gaming I think) prompted me to update my video card driver. Once I did that, my monitor's performance dramatically improved and I was able to succesfully calibrate it to see the fainter stuff.

Just a thought rather than throwing it out.

I don't really like LCD for astro images, but some of the new ones I have seen lately may change my mind.

Cheers

Geeday Tony,

Yes your right it is my monitor calibration. I usually have my brightness level of the monitor set to 35% and my contrast set to 75%. I then found this link http://pages.prodigy.net/ecmorris/tips/monitor.htm and adjusted my monitor accordingly. To my surprise this meant adjusting the brightness level to 67% (from 35%), and then I could see the bands in the Galaxy image, just like on my LCD display.

Yes I agree, I don't really like astro images on LCD either.

No, I'm not going to throw out the monitor but I guess one needs to bear in mind that most people are probably using LCD monitors to view our images on IIS and so they may be seeing the image much differently than how we think.

Maybe we should setup up an IIS Monitor Calibration Page so that all viewers might see all images as intended by the photographers ?

Paul

Itchy · #8 19-04-2006, 12:16 PM

Quote:

Originally Posted by PhotonCollector

Maybe we should setup up an IIS Monitor Calibration Page so that all viewers might see all images as intended by the photographers ?

Good idea Paul/ I guess you mean by having a greyscale bar and/or other devices that help people adjust their monitors.

I think I will see Iceman tonight. I will discuss it with him.

Cheers

ving (David) · #9 19-04-2006, 12:30 PM

tis a great image, bands or no bands paul!

Lester · #10 19-04-2006, 12:35 PM

Good one Paul. Looks like a kangaroo jumped into it on the bottom side. There numbers are increasing everywhere.

PhotonCollector (Paul) · #11 19-04-2006, 01:00 PM

Quote:

Originally Posted by Itchy

Good idea Paul/ I guess you mean by having a greyscale bar and/or other devices that help people adjust their monitors.

I think I will see Iceman tonight. I will discuss it with him.

Cheers

Hi Tony,

Yes that is precisely what I mean.

Paul M

PhotonCollector (Paul) · #12 19-04-2006, 01:04 PM

Quote:

Originally Posted by ving

tis a great image, bands or no bands paul!

Thanks Ving, yeah I liked the image too (aside from defects) because it shows a galaxy that appears unusual. The star matter appears to be getting pulled away from the centre of the galaxy, I thought that was very interesting. It's almost like there is a hidden object pulling away star matter.

Paul

ving (David) · #13 19-04-2006, 01:16 PM

like a black hole?