APOD: Arp 273: Battling Galaxies from Hubble (2019 Nov 20)

[Chris Peterson]

Something that I noticed when I had a chance to look at this APOD image on a larger display cinched the case that this is an artifact. If you also look at the very bright foreground star on the left edge of the galaxy you can see another (although dimmer) double ring effect.

And if you draw lines through their centres, they meet towards the middle of the image. If there was a third one at the bottom of the picture, it would point up towards the meeting point. It's a multiple internal reflection artifact inside the camera lens (not the telescope itself).

There is no "camera lens" as such. These artifacts are internal reflections of the primary mirror shadowed by the secondary, which is why they look like donuts. Most likely they are internal reflections in filters, but there are other possible surfaces they could also be from.

[geckzilla]

Something that I noticed when I had a chance to look at this APOD image on a larger display cinched the case that this is an artifact. If you also look at the very bright foreground star on the left edge of the galaxy you can see another (although dimmer) double ring effect.

And if you draw lines through their centres, they meet towards the middle of the image. If there was a third one at the bottom of the picture, it would point up towards the meeting point. It's a multiple internal reflection artifact inside the camera lens (not the telescope itself).

There is no "camera lens" as such. These artifacts are internal reflections of the primary mirror shadowed by the secondary, which is why they look like donuts. Most likely they are internal reflections in filters, but there are other possible surfaces they could also be from.

The donuts are officially described as filter ghosts. The hard lines are charge bleeds. This is why I make a significant and patient effort to remove these artifacts when I process my images. They tend to end up dominating any potential discussion with various people asking what they are and others trying to explain. It's no bueno

[DL MARTIN]

If as Chris Peterson contends that all that is being analyzed is the NOW, then what's the difference in that perspective and constant creation? I thought a static Universe went out with the advent of the BIG BANG.

[TheOtherBruce]

There is no "camera lens" as such. These artifacts are internal reflections of the primary mirror shadowed by the secondary, which is why they look like donuts. Most likely they are internal reflections in filters, but there are other possible surfaces they could also be from.

<headdesk> How did it slip my mind this is a Hubble pic, so there's no actual lens?

I'm curious about the relative positions and directions of motion involved here; I get the impression from the "tail" joining them that the galaxies are at least sort-of level with each other, making the collision close to edge-on. Is this accurate, or did the smaller galaxy punch through the disc of the big one? There seems to be a wider gap between the arms on one side over the other.

[neufer]

If as Chris Peterson contends that all that is being analyzed is the NOW, then what's the difference in that perspective and constant creation? I thought a static Universe went out with the advent of the BIG BANG.

• As a practical matter it is often useful to distinguish
  "news" from "history" (even if there is no clear demarcation line).

<<news (n.) late 14c., "new things," plural of new (n.) "new thing"; after French nouvelles, which was used in Bible translations to render Medieval Latin nova (neuter plural) "news," literally "new things." The English word was construed as singular at least from the 1560s, but it sometimes still was regarded as plural 17c.-19c. Meaning "tidings, intelligence of something that has lately taken place" is from early 15c.>>

<<history (n.) late 14c., "relation of incidents" (true or false), from Old French estoire, estorie "story; chronicle, history" (12c., Modern French histoire), from Latin historia "narrative of past events, account, tale, story," from Greek historia "a learning or knowing by inquiry; an account of one's inquiries, history, record, narrative," from historein "inquire," from histōr "wise man, judge."

Related to Greek idein "to see," and to eidenai "to know." In Middle English, not differentiated from story (n.1); sense of "narrative record of past events" probably first attested late 15c. Meaning "the recorded events of the past" is from late 15c. As a branch of knowledge, from late 15c. Meaning "a historical play or drama" is from 1590s. Sense of "systematic account (without reference to time) of a set of natural phenomena" (1560s) is now obsolete except in natural history. Meaning "an eventful career, a past worthy of note" (a woman with a history) is from 1852. To make history "be notably engaged in public events" is from 1862.>>

[Tcallaha]

Nobody addressed the comment in one of the first posts here about repeated background elements. I see many of them, like a pair of faint edge-on galaxies near a bright orange point that appear in the top left, top right, and bottom just right of center. Are they lensed background galaxies (I’m sure this group has enough gravity to do that and they do seem to arrange in kind of a circle around the center, although without the rotation and distortion I usually see with lenses) or some sort of photo processing mixup?

[BDanielMayfield]

And if you draw lines through their centres, they meet towards the middle of the image. If there was a third one at the bottom of the picture, it would point up towards the meeting point. It's a multiple internal reflection artifact inside the camera lens (not the telescope itself).

There is no "camera lens" as such. These artifacts are internal reflections of the primary mirror shadowed by the secondary, which is why they look like donuts. Most likely they are internal reflections in filters, but there are other possible surfaces they could also be from.

The donuts are officially described as filter ghosts. The hard lines are charge bleeds. This is why I make a significant and patient effort to remove these artifacts when I process my images. They tend to end up dominating any potential discussion with various people asking what they are and others trying to explain. It's no bueno

I was hoping that you would weigh in on this geck, given your vast experience processing Hubble data.

[Tara_Li]

Nobody addressed the comment in one of the first posts here about repeated background elements. I see many of them, like a pair of faint edge-on galaxies near a bright orange point that appear in the top left, top right, and bottom just right of center. Are they lensed background galaxies (I’m sure this group has enough gravity to do that and they do seem to arrange in kind of a circle around the center, although without the rotation and distortion I usually see with lenses) or some sort of photo processing mixup?

I gotta admit - I'm seeing this duplication of elements as well. What *is* up with these?

[Chris Peterson]

Nobody addressed the comment in one of the first posts here about repeated background elements. I see many of them, like a pair of faint edge-on galaxies near a bright orange point that appear in the top left, top right, and bottom just right of center. Are they lensed background galaxies (I’m sure this group has enough gravity to do that and they do seem to arrange in kind of a circle around the center, although without the rotation and distortion I usually see with lenses) or some sort of photo processing mixup?

I gotta admit - I'm seeing this duplication of elements as well. What *is* up with these?

It's pretty simple. For reasons unknown, presumably aesthetic, the image processor chose to rotate the entire Hubble frame from the original orientation. That resulted in dead space in all four corners where there was no image data. So rather than leaving those areas blank (which would have been the scientific thing to do), he chose to fill those areas in with star fields that aren't actually present in those areas.

[Chris Peterson]

If as Chris Peterson contends that all that is being analyzed is the NOW, then what's the difference in that perspective and constant creation? I thought a static Universe went out with the advent of the BIG BANG.

The "now" that existed when I made my earlier post isn't the same "now" as when I'm making this one. That isn't a "static Universe".

You're worrying about "when" something happened, when what matters is where this object is in its evolution as we're seeing it. Which makes its distance of no value. When you're halfway through a movie, considering the action in light of what was happening in that movie over the last hour, do you worry about the fact that the movie was filmed a year ago?

[RickyM]

What a terrible picture for todays APOD, A total copy & paste job,

[Tara_Li]

It's pretty simple. For reasons unknown, presumably aesthetic, the image processor chose to rotate the entire Hubble frame from the original orientation. That resulted in dead space in all four corners where there was no image data. So rather than leaving those areas blank (which would have been the scientific thing to do), he chose to fill those areas in with star fields that aren't actually present in those areas.

It's not just a scientific matter, it's a matter of trust. People see images like this, and start asking questions about *other* images. This is the kind of thing that gets us Flat Earthers and Moon Landing Conspiracy nuts.

[BDanielMayfield]

It's pretty simple. For reasons unknown, presumably aesthetic, the image processor chose to rotate the entire Hubble frame from the original orientation. That resulted in dead space in all four corners where there was no image data. So rather than leaving those areas blank (which would have been the scientific thing to do), he chose to fill those areas in with star fields that aren't actually present in those areas.

It's not just a scientific matter, it's a matter of trust. People see images like this, and start asking questions about *other* images. This is the kind of thing that gets us Flat Earthers and Moon Landing Conspiracy nuts.

You make a valid point Tara_Li, but surely you're jesting about being a nut yourself. Yes, it is true that we've come to expect a higher level of, well I guess honesty in the images given the honor of being selected as an APOD. And since one of strange thinkers favorite targets is NASA, and this a NASA supported website, 1 + 2 = 5, obviously.

Bruce

[BDanielMayfield]

What a terrible picture for todays APOD, A total copy & paste job,

But, I wouldn't go so far as to call it terrible though. By pushing the data farther than normal the artist was able to bring out more subtle details like dust strips and faint tidal star trail loops. Those parts were excellent, and I'm sure where what caused its selection.

[Chris Peterson]

What a terrible picture for todays APOD, A total copy & paste job,

But, I wouldn't go so far as to call it terrible though. By pushing the data farther than normal the artist was able to bring out more subtle details like dust strips and faint tidal star trail loops. Those parts were excellent, and I'm sure where what caused its selection.

Maybe, maybe not. I see odd streamers and structure that is along the edges and aligned with the orientation of the source image. I see optical artifacts brought up to levels higher than real structure. I don't have a high level of confidence about what is or is not real structure in this image. I think it's overprocessed, regardless of the inserted data.

[BDanielMayfield]

What a terrible picture for todays APOD, A total copy & paste job,

But, I wouldn't go so far as to call it terrible though. By pushing the data farther than normal the artist was able to bring out more subtle details like dust strips and faint tidal star trail loops. Those parts were excellent, and I'm sure where what caused its selection.

Maybe, maybe not. I see odd streamers and structure that is along the edges and aligned with the orientation of the source image. I see optical artifacts brought up to levels higher than real structure. I don't have a high level of confidence about what is or is not real structure in this image. I think it's overprocessed, regardless of the inserted data.

If there are streamers and structure that isn't real, then, as geck put it, it's very much "no bueno".

The defects have totally overwhelmed what should have been a discussion about galaxy interaction. That's what I was thinking of commenting about when I first saw the image and read the explanation, but then reading people's posts about this or that flaw derailed my intention.

[Chris Peterson]

If there are streamers and structure that isn't real, then, as geck put it, it's very much "no bueno".

The defects have totally overwhelmed what should have been a discussion about galaxy interaction. That's what I was thinking of commenting about when I first saw the image and read the explanation, but then reading people's posts about this or that flaw derailed my intention. :thumb_down:

Here's what I was talking about. The red line shows the boundry of the actual HST data. Everything outside that came from somewhere else. Mouse over this and you'll see an intensified version of the APOD that shows actual galactic structure outside the data boundary. Where did that come from? Cloned stars and painted in gas? Something's just not right here.
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Click to view full size image 1 or image 2