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Wow, that looks really good! As for artefacts, I'll leave that for the experts to decideHere is a comparison between the mathematical process which remaps the pixel values in the image and using the camera software.
Professional astronomers use FITS Liberator for processing images which I find does not enhance the faint detail as well as the mathematical process.
Ultimately the experts were satisfied.Wow, that looks really good! As for artefacts, I'll leave that for the experts to decide
Olivier Hanault said:Dear Steven,
Impressive data processing! It is very hard to evaluate it in details on the re-scaled JPG (which loses lots of information wrt the FITS), but here are some comments:
- The noise texture in the background, and the large-scale flatness of the background suggests you have used a sky-subtraction algorithm (which is OK) using a sampling window that is too small (probably 100pix, while you could push it to ~500 or 1000)?
- the overall depth of the image is really good!
- combining the data over a huge wavelength range UBVI can be counter productive, even if your only goal is to go deep. For instance, the individual U images tend to be much shallower (because the camera is less sensitive in U, and bc the stars are fainter in U), so if you average them with the others without a different weight, you actually increase the noise more than the signal. You could consider to use the following weight for each image:
w = F/t
with t = exposure time (i.e. normalize by exposure time) and
F(U) = 0.2; F(B) = 0.4; F(V) = 1; F(R) = 1.5; F(I) = 0.8
An other way would be to pick a star that is not saturated in any of the images and that has neutral colours in our image, and normalize the frames by the (sky-subtracted) flux of that star.
If you have the time/the patience, you could give it a try, and I would not be surprised if the end result is a little deeper.
Note also that for the astronomers, combining all the filters together is usually not useful. It can help to create a catalogue of positions of the starts, and then go back and measure the flux in the single-filter recombinations U, B, V, R, I.
- the stretch function you apply is very good for displaying the image - but for us the only useful one is the original linear pixels. The stretch functions are really just for display. Anything that screws up the linearity of the data is a problem (and actually, we sometimes have problems with the raw data being not perfectly linear).
Cheers
oli
Very nice! I suppose the type and amount of data manipulation will depend on the purpose of the processing.Ultimately the experts were satisfied.
I sent an image to ESO of the Carina Dwarf Galaxy one of the Milky Way satellite galaxies.
This galaxy is so notoriously faint it's surface brightness is fainter than the natural skyglow in the Earth's upper atmosphere.
It is theoretically possible to image as the combined surface brightness of the galaxy and the Earth's skyglow is fractionally brighter than the skyglow alone.
This is a 50 hr exposure with a small 28 cm telescope and a CCD which sophisticated by amateur standards is primitive to the state of the art CCDs used by professional astronomers.
The galaxy is invisible on the right when processed conventionally.
ESO were dubious to put it mildly as they thought it was impossible to image the Carina Dwarf using amateur equipment.
They did however provide me with their unprocessed data of the Carina Dwarf taken with the 4 metre and 2.2 metre telescopes from Chile.
ESO stipulated the conditions for processing.
(1) No sharpening
(2) No contrast enhancement.
(3) No colour saturation.
(4) No photo-shopping etc.
The data was processed using the maths process and Fits Liberator which is the standard processing package used by the professionals.
I decided to process the data as a monochrome image.
The left hand image is the maths processed image the right hand processed with FITS liberator.
Whereas my amateur image shows the Carina dwarf as a "cloud" the larger professional scopes resolves the cloud into individual stars in a smaller field of view.
While they were critical in how I combined their individual images they gave the left hand image the thumbs up as being the real thing not composed of artefacts.
Being non linear processing the left hand image cannot be used be used for astronomical photometry.
Here is an image I took of the Antares region (red star on the right) taken with very simple equipment a 300mm telephoto lens and a Pentax k-r camera, no telescope, no fancy ultra cooled CCD equipment.
I have been able to develop a mathematical process where very faint detail can be brought out without excessively increasing the noise.
More importantly than the sense of awe we get, (and rightly so), is the successfully demonstrated application of math in physics, which generated that awe.Are you using any sort of equipment to "track" the object over time? The images you're getting are simply amazing.
One of the main aspects of data manipulation is to improve the aesthetic value of the image.Very nice! I suppose the type and amount of data manipulation will depend on the purpose of the processing.
The CCD I use has an imaging chip and a tracking chip.Are you using any sort of equipment to "track" the object over time? The images you're getting are simply amazing.
The CCD I use has an imaging chip and a tracking chip.
The tracking chip locks in on a guide star and takes images of the star in short intervals.
If the star moves on the chip between intervals the CCD sends a signal to the equatorial mount which makes an adjustment.
Life is far easier than it was 20+ years ago in the age of using film and tracking manually.
Being stuck on top of a mountain in below freezing temperatures doing 3hr+ exposures while glued to the guiding eyepiece was the height of masochism.
More importantly than the sense of awe we get, (and rightly so), is the successfully demonstrated application of math in physics, which generated that awe.
Ie: its not just a simple case of relying on high precision equipment .. as is evidenced by the lack of detail in the raw (unprocessed) images.
@Astrophile .One of the main aspects of data manipulation is to improve the aesthetic value of the image.
The Hubble images presented by NASA for public consumption have a whizzbang factor, which has more of a PR effect than scientific value; the data studied by astronomers is far more mundane.
Manipulating the data so as to go deeper in an image does have scientific value and can be useful for supernova surveys and hunting for fainter more distant galaxies as examples.
Once a discovery is made linear processing is required in order for the science to be done.
Very nice! I suppose the type and amount of data manipulation will depend on the purpose of the processing.
An impressive feat to get the signature pinned down for strontium.Strontium discovered in neutron star merger.
The r-process or rapid neutron capture process is believed to be responsible for the production of at least half the nuclei heavier than iron (Fe).
Until now the environment in which the r-process occurs was uncertain.
First Identification of a Heavy Element Born from Neutron Star Collision - Newly created strontium, an element used in fireworks, detected in space for the first time following observations with ESO telescope
Exciting news. Thanks for sharingCompelling interesting news:
A relatively nearby very large Red Giant star is dimming a lot(!)
https://phys.org/news/2019-12-betelgeuse-tempestuous-star.html
"Astronomers have observed reservoirs of cool gas around some of the earliest galaxies in the universe. These gas halos are the perfect food for supermassive black holes at the center of these galaxies, which are now seen as they were over 12.5 billion years ago. This food storage might explain how these cosmic monsters grew so fast during a period in the universe's history known as the Cosmic Dawn."Astronomy and Astrophysics News, photos, articles.
It could be fun to have a post/thread for the many believers (and seekers too) that like to see interesting Astronomy and Astrophysics and Cosmology News and articles.
Meaning stuff that is interesting news from observations, and photos/images from those.
New ideas/hypothesis from science articles trying to understand more about how stars work.
And galaxies
And collapsars (Neutron Stars and Black Holes, white dwarfs, etc.)
And the Universe large structure and change over time.
In astrophysics, cosmology, vanguard physics, the normal process is just like grouping in big dark room with a tiny light that barely allows us to see a bit nearby at times. That's normal."Astronomers have observed reservoirs of cool gas around some of the earliest galaxies in the universe. These gas halos are the perfect food for supermassive black holes at the center of these galaxies, which are now seen as they were over 12.5 billion years ago. This food storage might explain how these cosmic monsters grew so fast during a period in the universe's history known as the Cosmic Dawn."
ESO observations reveal black holes' breakfast at the cosmic dawn
It seems science news these days is getting indistinguishable from guesses. Kind of like guessing what the Jolly Green Giant ate on his first breakfast.
OK, happy groping in the dark I guess.In astrophysics, cosmology, vanguard physics, the normal process is just like grouping in big dark room with a tiny light that barely allows us to see a bit nearby at times. That's normal.
Indeed. It's just as well that science news and science are not the same thing. Perhaps if you appreciated that and let it inform your thinking you would be less confused on scientific matters.It seems science news these days is getting indistinguishable from guesses. Kind of like guessing what the Jolly Green Giant ate on his first breakfast.
If three dozen Catholic priests and a dozen nuns were running around with machine guns holding up banks and corner stores, and shooting children under 6 years old, people would wonder about Catholicism. When dozens of scientists make statements and conduct experiments people associate that with science. Looking at the article cited, it uses scientific premises. How big the universe is, and how stars form. and what they eat, and the BB starting point etc. You can't disassociate this from science.Indeed. It's just as well that science news and science are not the same thing. Perhaps if you appreciated that and let it inform your thinking you would be less confused on scientific matters.
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