Hubble Telescope data sets

[Rodd]

I have little else to do of late due to the unending clouds, so I decided to try some Hubble images.  These images consist of 1 sub per channel.  If I were to image these galaxies with the C11Edge at 2,800 mm, they would be tiny dots.  The subs for these images arrive in deplorable conditions--often each sub is a mosaic of 3 panels.  After combination strange crops are required as the panels do not necessarily line up beyond the target.  But, once you have a cropped, color calibrated image, processing is not difficult (it is still hard to achieve excellence).  Gradients don't exist for the most part.  Its hard to believe that each channel is but 1 sub

NGC 6050

Arp 274

 

Arp 87

 

Arp 147

 

 

 

 

[Sunshine]

How much time did this requirer per image? I think it is really neat that one is able to work on Hubble data.

[Rodd]

21 minutes ago, Sunshine said:

How much time did this requirer per image? I think it is really neat that one is able to work on Hubble data.

Not that much to tell the truth--less than my own images.  I processed all of these in one evening.  The data processes very well, it just starts out looking a bit intimidating.  There are no gradients, no light pollution, no noise to speak of.  The only thing is I wish there was more than 1 sub per channel.  Its hard to achieve a really polished image like you can get with 30-40 hours of good ground based data.  Maybe there is more data--finding it is the trouble.  A friend doenloaded these data sets so i did not have to hunt for them and figure out what filter was what.  

[Sunshine]

Maybe the clouds were rolling in and they only had time for one sub per channel 🤣😂

It seems the first image, NGC 6050 is 450 million light years away, astounding, considering Andromeda's two LY distance. It is fascinating and humbling just thinking about such

distances, our minds are not accustomed to thinking at such scales and distances. Traveling 450 million years at some three hundred thousand km per second. it makes me wish

I could hop in a ship and, head off towards this galaxy, just to see for myself, only then can I full comprehend.

 

Edited February 14, 2021 by Sunshine

[Knight of Clear Skies]

Very nice Rodd, would be nice to see these alongside a wider view. Looking at professional data the WISE set covers the entire sky, have you looked into that at all? I've been experimenting with Ha/IR composites as the visible Ha is just a skin on much larger hidden structures.

[PhotoGav]

Superb images and an interesting project. Do you have further information about which filters were used for the data here? I have briefly looked at the Hubble Archive, but not yet fathomed what to look for to create a colour image. All help gratefully received!

[Rodd]

1 hour ago, Knight of Clear Skies said:

Very nice Rodd, would be nice to see these alongside a wider view. Looking at professional data the WISE set covers the entire sky, have you looked into that at all? I've been experimenting with Ha/IR composites as the visible Ha is just a skin on much larger hidden structures.

I wouldn't know how to get the data.  I don't really know how to get the Hubble data.  A friend linked me to a page that had these data sets ready for download.  You have to hunt through lists of files taken over years.  Getting the data is harder than processing it!  The sensor is irregular (like a staircase)--you have seen teh ultra deep field--well, its like that for all images.  After channel combination, there are black spaces, and lines between the sections.  Cropping is necessary to avoid artifacts.  Otherwise--the FOV would be a bit larger.

[Rodd]

1 hour ago, PhotoGav said:

Superb images and an interesting project. Do you have further information about which filters were used for the data here? I have briefly looked at the Hubble Archive, but not yet fathomed what to look for to create a colour image. All help gratefully received!

The red filter is i, the green filter is v, and the blue filter is b.  Ha is h, but I have found the Ha subs to be unusable--very weak and noisy, full of streaks and lines.  The Ha signal is strangely not that bright.  Maybe these galaxies don't have much Ha.  Its a shame because I love adding Ha to galaxies.  

There is a c filter too--and a couple of others, but I don't know what they are.  I wish they would label the darn things :LRGB Ha, OIII, and SII.  The filter names are not easy to find either--I have not found them.  I took a guess that i was red.  I knew v was verde (green).  b was obvious, as is h. Other than that, I have no clue!

[Knight of Clear Skies]

47 minutes ago, Rodd said:

I wouldn't know how to get the data.

WISE data can be downloaded here. The search parameters take a bit of messing around with but here's an example search which returns several panes around Sh2-264, in four different wavelengths.

You can click on the different panes on the left to see them in more detail.

Here's a screen grab of what I put in the search parameters.

Hope that's of some interest. You can see an example composite in this thread.

Edited February 15, 2021 by Knight of Clear Skies

[PhotoGav]

37 minutes ago, Rodd said:

The red filter is i, the green filter is v, and the blue filter is b.  Ha is h, but I have found the Ha subs to be unusable--very weak and noisy, full of streaks and lines.  The Ha signal is strangely not that bright.  Maybe these galaxies don't have much Ha.  Its a shame because I love adding Ha to galaxies.  

There is a c filter too--and a couple of others, but I don't know what they are.  I wish they would label the darn things :LRGB Ha, OIII, and SII.  The filter names are not easy to find either--I have not found them.  I took a guess that i was red.  I knew v was verde (green).  b was obvious, as is h. Other than that, I have no clue!

Thanks Rodd, I will brave the system again and see if I can get a bit further. 

With regards to filter naming, I was under the impression that V stood for Visual, i.e. around the Green wavelengths. I like the idea that it stands for Verde though.

[Rodd]

9 minutes ago, PhotoGav said:

With regards to filter naming, I was under the impression that V stood for Visual, i.e. around the Green wavelengths. I like the idea that it stands for Verde though.

I am just guessing as I have heard V stand for verde (which is French for green).  All I know is it works as a green!

[Rodd]

25 minutes ago, Knight of Clear Skies said:

Hope that's of some interest. You can see an example composite in this thread.

How wide a field is it?  It would be nice to get some data of nebulae--but are they all like full constellation FOVs?

[Knight of Clear Skies]

On 15/02/2021 at 14:39, Rodd said:

How wide a field is it?  It would be nice to get some data of nebulae--but are they all like full constellation FOVs?

There is data coverage for the whole sky. WISE has a 16" telescope and the resolution is between 6 and 12 arc-seconds/pixel in the 4 bands, so it plays well with optical data from telescopes and camera lenses. This was my quick effort on the Angelfish.

[Rodd]

35 minutes ago, Knight of Clear Skies said:

6 and 12 arc-seconds/pixel

That is very low resolution.  The pixel size must be huge.  I dream of the same FOV and aperture with teeny tiny pixels, so one can zoom WAY in and crop images that resemble long focal length images.  

[Knight of Clear Skies]

1 hour ago, Rodd said:

That is very low resolution.  The pixel size must be huge.  I dream of the same FOV and aperture with teeny tiny pixels, so one can zoom WAY in and crop images that resemble long focal length images.  

The longer the wavelength of the light the lower the resolution. A 10 metre radio telescope dish has an angular resolution of about a degree.=

This is the Witch's Head from WISE. Looking at it, I'm not sure the resolution I quoted is accurate.

Edited February 18, 2021 by Knight of Clear Skies

[tomato]

The V for green might be a scientific convention as the green channel from the Las Cumbres Observatory Project has the same designation.

If you are going to use remote data, you might as well have the best there is.

[Rodd]

3 minutes ago, tomato said:

If you are going to use remote data, you might as well have the best there is

Agreed--but if one has the best there is, shouldn't they be afforded ENOUGH of it?  Can you imagine what the images would look like if instead of 1 sub per channel there were 10?  I found the Hubble data sets to be way noisier than I thought they would be, and way less accepting of sharpening.  

[tomato]

23 minutes ago, Rodd said:

Agreed--but if one has the best there is, shouldn't they be afforded ENOUGH of it?  Can you imagine what the images would look like if instead of 1 sub per channel there were 10?  I found the Hubble data sets to be way noisier than I thought they would be, and way less accepting of sharpening.  

Well, the HST was launched in 1989 with the original repair mission in 1993. I'm sure they installed cutting edge sensors back then but the 1990's technology must have had it's limitations. I wonder did subsequent service missions install better cameras?

[Rodd]

7 minutes ago, tomato said:

Well, the HST was launched in 1989 with the original repair mission in 1993. I'm sure they installed cutting edge sensors back then but the 1990's technology must have had it's limitations. I wonder did subsequent service missions install better cameras?

You also have to keep in mind that the technology that they used was cutting edge stuff--way beyond what was available to the general public.  The cameras cost millions.  I would be willing to bet that if you compared the Hubble camera to a modern amateur camera say an ASI 1600--or a higher end CCD ($10-15,000 range) the Hubble camera would leave it in the dust. 

[tomato]

So if the cameras are that good, and don't have the inherent noise generation that our amateur kit has, and for sure the HST has pristine skies, where is the noise coming from?

[tomato]

Plenty of images available through this portal, they appear to be raw monochrome images, but a quick search on NGC 6050 doesn't present any obvious (at least to me) LRGB data sets, single subs or otherwise.

Getting Started: Hubble Legacy Archive (stsci.edu)

[Rodd]

6 minutes ago, tomato said:

So if the cameras are that good, and don't have the inherent noise generation that our amateur kit has, and for sure the HST has pristine skies, where is the noise coming from?

Well--I did not say they were perfect.  Nowhere near as what is able to be made (at that level) today (still far better than my $1,000 camera).  Also, there is only 1 sub per channel.  Also, these target are 500,000,000 to a billion light years away.  As I said--I bet if there were 10 subs per channel, the images would be amazing

[Rodd]

3 minutes ago, tomato said:

Plenty of images available through this portal, they appear to be raw monochrome images, but a quick search on NGC 6050 doesn't present any obvious (at least to me) LRGB data sets, single subs or otherwise.

Getting Started: Hubble Legacy Archive (stsci.edu)

Yes--you have to cull the list and assemble the RGB sets yourself.  Each one of those files is a single sub.  that is what is time consuming.  You have to open each one and look--to make sure its of the same target with the same FOV.  And you have to know something about teh filters.

[tomato]

OK, thanks, the filter designations are indeed far from obvious, I couldn't see anything under Spectral Elt for the NGC 6050 list resembling i, v or b.

[Rodd]

7 minutes ago, tomato said:

OK, thanks, the filter designations are indeed far from obvious, I couldn't see anything under Spectral Elt for the NGC 6050 list resembling i, v or b

You also have to look at the level column--5 is a color image 1 is raw.  I am not sure what 2-4 mean.  Obviously you want 1 or 2 (2 might be calibrated?).  Not sure.  I do know that the subs I used were calibrated and aligned.  The problem with the filters is they often give wavelengths--so if you don't work with them every day--its hard to know without having a master list to work from.  As I said--getting the data is a pain.  I was fortunate to have a friend link me to a list of prefound subs.  I will link that same list to you here when I have access to my computer later