Starship Asterisk*

Ann wrote: ↑Mon Jul 18, 2022 5:05 am Stephan's Quintet looks amazing in the combined Hubble, JWST and Subaru image, processed by Rob Gendler.
But my favorite Stephan's Quintet image is the one by JWST's MIRI (Mid-infrared instrument). Just look at what it shows us!
Ann

sc02492 wrote: ↑Mon Jul 18, 2022 8:54 am This is a pretty image, expertly processed. However, the red, visible light signal from Hubble (and other visible light sources) is now conflated with the IR signal(s) of JWST- that would be fine if they represented similar spatial and intensity distributions of light, but this isn't necessarily the case. Lumping them together in the red channel potentially compromises the ability to identify the independent and unique contribution of JWST compared to Hubble/visible light (which is what makes JWST exciting!). In my opinion, JWST data are more easily interpreted and appreciated when they stand on their own, (and/or perhaps presented as a rollover with visible light data so that the audience can explore the differences). Admittedly there is no right or wrong way to portray what is essentially an artistic representation of the data, as in this case.

Steve Cannistra
www.starrywonders.com

sc02492 wrote: ↑Mon Jul 18, 2022 8:54 am This is a pretty image, expertly processed. However, the red, visible light signal from Hubble (and other visible light sources) is now conflated with the IR signal(s) of JWST- that would be fine if they represented similar spatial and intensity distributions of light, but this isn't necessarily the case. Lumping them together in the red channel potentially compromises the ability to identify the independent and unique contribution of JWST compared to Hubble/visible light (which is what makes JWST exciting!). In my opinion, JWST data are more easily interpreted and appreciated when they stand on their own, (and/or perhaps presented as a rollover with visible light data so that the audience can explore the differences). Admittedly there is no right or wrong way to portray what is essentially an artistic representation of the data, as in this case.

Steve Cannistra
www.starrywonders.com

De58te wrote: ↑Mon Jul 18, 2022 3:29 pm I am a bit confused. The Apod introduction states that the James Webb telescope can't see blue color, only up to orange. Yet the infrared picture of the nebula that Orin Stepanek posted and he attributed to the JWST still shows the blue portion of the nebula, although a little fainter, yet the orange part of the nebula has disappeared. Me thinks maybe that is a Hubble photo?

Chris Peterson wrote: ↑Mon Jul 18, 2022 2:04 pm

sc02492 wrote: ↑Mon Jul 18, 2022 8:54 am This is a pretty image, expertly processed. However, the red, visible light signal from Hubble (and other visible light sources) is now conflated with the IR signal(s) of JWST- that would be fine if they represented similar spatial and intensity distributions of light, but this isn't necessarily the case. Lumping them together in the red channel potentially compromises the ability to identify the independent and unique contribution of JWST compared to Hubble/visible light (which is what makes JWST exciting!). In my opinion, JWST data are more easily interpreted and appreciated when they stand on their own, (and/or perhaps presented as a rollover with visible light data so that the audience can explore the differences). Admittedly there is no right or wrong way to portray what is essentially an artistic representation of the data, as in this case.

Steve Cannistra
www.starrywonders.com

You can't produce a color image from multichannel data that is going to clearly show the data from those channels. You can play with different palettes all day, but the bottom line is that you hide information and much of the convolution is irreversible.

On the whole, it is best to think of these releases as aesthetic, not scientific. We can glean some information from the color, we can learn a lot about structure, but if science is the goal, we need to work with each channel independently. We can't combine them into a single color image.

AVAO wrote: ↑Mon Jul 18, 2022 3:59 pm

Chris Peterson wrote: ↑Mon Jul 18, 2022 2:04 pm

sc02492 wrote: ↑Mon Jul 18, 2022 8:54 am This is a pretty image, expertly processed. However, the red, visible light signal from Hubble (and other visible light sources) is now conflated with the IR signal(s) of JWST- that would be fine if they represented similar spatial and intensity distributions of light, but this isn't necessarily the case. Lumping them together in the red channel potentially compromises the ability to identify the independent and unique contribution of JWST compared to Hubble/visible light (which is what makes JWST exciting!). In my opinion, JWST data are more easily interpreted and appreciated when they stand on their own, (and/or perhaps presented as a rollover with visible light data so that the audience can explore the differences). Admittedly there is no right or wrong way to portray what is essentially an artistic representation of the data, as in this case.

Steve Cannistra
www.starrywonders.com

You can't produce a color image from multichannel data that is going to clearly show the data from those channels. You can play with different palettes all day, but the bottom line is that you hide information and much of the convolution is irreversible.

On the whole, it is best to think of these releases as aesthetic, not scientific. We can glean some information from the color, we can learn a lot about structure, but if science is the goal, we need to work with each channel independently. We can't combine them into a single color image.

Your comment describes very precisely one of the basic problems in creating astronomical images according to scientific principles. However, I would not judge the multi-wavelength image produced by Robert Gendler as purely aesthetically and scientifically worthless and I hope that you can also agree with the following argument:

It is only the resulting pixelbased color values ​​that become meaningless. Even if several wavelength spectra are combined, scientific values can be generated if, for example, the overall structural appearance of astronomical objects is better visible.


Crab Nebula NASA / ESA

The example of Stephan's Quintet from today's APOD is extremely difficult to understand structurally and spatially. This is exactly where color differences like in Ann's example of the "small" background galaxy behind NGC 7320 help us to see this more clearly and thus to be able to understand it better.

Chris Peterson wrote: ↑Mon Jul 18, 2022 3:38 pm

De58te wrote: ↑Mon Jul 18, 2022 3:29 pm I am a bit confused. The Apod introduction states that the James Webb telescope can't see blue color, only up to orange. Yet the infrared picture of the nebula that Orin Stepanek posted and he attributed to the JWST still shows the blue portion of the nebula, although a little fainter, yet the orange part of the nebula has disappeared. Me thinks maybe that is a Hubble photo?

HST and JWST images are instantly distinguished from each other by looking at the diffraction spikes. While we can't say for absolute certainty that the IR image comes from the HST, we can know that it doesn't come from the JWST. (In fact, however, the near IR frame is an HST image.)

Comparison of the Carina Nebula in visible light (left) and infrared (right), both images by Hubble. In the infrared image, we can see more stars that weren't visible before. Credit: NASA/ESA/M. Livio & Hubble 20th Anniversary Team (STScI)

PDemosthenes wrote: ↑Fri Aug 05, 2022 11:03 pm I would love it if NASA would typically mention the span of an object. Usually in light years. most of us earth bounds have little understanding of how huge many of these objects are.

VictorBorun wrote: ↑Sat Aug 06, 2022 12:01 am

PDemosthenes wrote: ↑Fri Aug 05, 2022 11:03 pm I would love it if NASA would typically mention the span of an object. Usually in light years. most of us earth bounds have little understanding of how huge many of these objects are.

...

johnnydeep wrote: ↑Sat Aug 06, 2022 7:49 pm

VictorBorun wrote: ↑Sat Aug 06, 2022 12:01 am

PDemosthenes wrote: ↑Fri Aug 05, 2022 11:03 pm I would love it if NASA would typically mention the span of an object. Usually in light years. most of us earth bounds have little understanding of how huge many of these objects are.

...

Except that the left most member of the quintet - NGC 7320 - is only 40 Mly away, and the other 4 members are an average of 300 Mly away. So, if NGC 7320 was moved to 300 Mly away in this view, it would appear 7.5 times smaller than it does here.

[ EDIT: I thought I had posted this 6 hours earlier, but apparently only "previewed" it and forgot to "submit" it. ]