Stephan's Quintet ar 20m fl

[DaveS]

I didn't realise there was data on this in the School's Observatory archive until I posted a question on the forum. It turns out that you have to have a teacher or student account as the data is in the GCSE Astronomy section.

When I looked I found a lot of images, this is just 120 seconds of R, G, And B. I had to do a gradient removal and a DDP followed by a couple of histogram stretches, ending with a lw-pass filter to get rid of the noise.

The rest of the images in the archive are just 60 and 90 sec which might be OK for preserving the cores.

There's more structure in the image, including the tidal tail but it's very noisy.

[MikeODay]

A very nice image Dave of an interesting set of galaxies; thanks for sharing.

 Did I understand correctly that this is from data you have downloaded?  If so, do you have details of the scope used, etc.?

Cheers

Mike

[DaveS]

It's from the Liverpool Telescope on La Palma, accessed through the National Schools' Observatory. I have a Teacher's account.

The telescope has a 2m dia primary, is a RC design and works at f/10, giving a 20m FL. The sensor has 15 micrometre pixels, binned 2x2 giving 0.3" PP.

The image is made from just single subs of 120 sec in each of R, G, and B. As a result it's a bit noisy. I think I'll have a look to see if there's any more data in the archive.

[MikeODay]

Thank you Dave for all the information on the scope and capture.  

You did a very good job with so little data!

Cheers

Mike

[wimvb]

On 2017-12-05 at 19:56, DaveS said:

I didn't realise there was data on this in the School's Observatory archive until I posted a question on the forum. It turns out that you have to have a teacher or student account as the data is in the GCSE Astronomy section.

When I looked I found a lot of images, this is just 120 seconds of R, G, And B. I had to do a gradient removal and a DDP followed by a couple of histogram stretches, ending with a lw-pass filter to get rid of the noise.

The rest of the images in the archive are just 60 and 90 sec which might be OK for preserving the cores.

...

There's more structure in the image, including the tidal tail but it's very noisy.

Lovely. having a "slightly" larger looking glass sure helps, doesn't it. I think you can also use the 60 and 90 second exposures. More will bring the noise down and allow you to use pixel rejection to get rid of cosmic rays and hot pixels. When I used the LT data, I basically put anything longer than 30 seconds in the pot. What software do you use to process the data?

[toxic]

ooh thats blooming close you got the hubble or what 

nice one Dave

[DaveS]

I'll have another look, and download the 60 and 90 sec exposures as well.

ATM I do most of the processing in AstroArt as I find the DDP routine very good for galaxies. I've also started to use GIMP 2.9 but it doesn't like 16 bit TIFFs so I use the PNG.

[Chris]

Thanks for posting this, Dave   I've never seen the quintet at this kind of image scale before. I've imaged this group myself back in 2004 using a C14 (University scope not mine unfortunately) even with a 14" mirror and several metres of FL it was still just a small clump of fuzzy dots.

The image you've posted above is impressive. 

 

 

[DaveS]

Thanks Lockie.

What's slightly amazing is that this professional 2m telescope is available for schools to use for free. Others can access it too, but with more limitations.