Starship Asterisk*

bystander wrote: ↑Sun Sep 05, 2021 9:38 pm Windows has an accessory called Character Map (in the Start Menu under Window Accessories). You can find all of the Unicode characters there.

Ann wrote: ↑Mon Sep 06, 2021 4:36 am

bystander wrote: ↑Sun Sep 05, 2021 9:38 pm Windows has an accessory called Character Map (in the Start Menu under Window Accessories). You can find all of the Unicode characters there.

The word Unicode is Greek to me. Sorry.

Ann

bystander wrote: ↑Sun Sep 05, 2021 9:38 pm Windows has an accessory called Character Map (in the Start Menu under Window Accessories). You can find all of the Unicode characters there.

Ann wrote: ↑Sun Sep 05, 2021 5:16 pm

Chris Peterson wrote: ↑Sun Sep 05, 2021 1:28 pm

johnnydeep wrote: ↑Sun Sep 05, 2021 1:06 pm

I'm not Victor, but I thought they might just be unicode characters. His "square" is really two chars side-by-side. I thought they might be one of the "geometric shapes" shown here - https://www.unicodepedia.com/groups/geometric-shapes/ - but none exactly match what Victor used. Though the "black vertical rectagle" comes close: ▮, but it's not big enough! Can it be colorized with the "font color" tool in the post editor? Let's see: ▮▮▮. Yup! But there is also space between successive chars, which Victor's double black box chars don't have. I still suspect it's a unicode char however.

Sure. You can just look at it in the quoted text. It's Unicode U+2588, Full Block. In Windows you type it using ALT-219 (█) or a pair of those (██). As an ordinary character, you can apply whatever styling BBCODE offers: █.

Thanks, Chris, ALT-219 works: █

And I can make it colorful: █ █ ██ █ █ ██ █ █ █

Thanks, it works!

Ann

neufer wrote: ↑Sun Sep 05, 2021 5:39 pm

Ann wrote: ↑Sat Sep 04, 2021 4:43 pm

neufer wrote: ↑Sat Sep 04, 2021 3:57 pm

• Are you sure https://apod.nasa.gov/apod/ap180801.html

Pretty sure...

To my eyes your "star cluster" looks indistinguishable from the background Milky Way:

• https://apod.nasa.gov/apod/ap180801.html

The "top hat cavity" is just one of numerous holes in the dust curtain, IMO.

Ann wrote: ↑Sat Sep 04, 2021 4:43 pm

neufer wrote: ↑Sat Sep 04, 2021 3:57 pm

Ann wrote: ↑Sat Sep 04, 2021 6:11 am
Okay, I promised you: That's star cluster NGC 7023 (top) in the Iris Nebula!
The cluster is responsible for the "top hat cavity" at top.

I can see that the arrows I drew make it look as if some force is pushing the dust inwards, toward the middle. Of course, the opposite is true. It is the wind and ultraviolet light from the hot bright star that pushes the dust outwards, creating both the cavity around the star and and the edges of gas and dust that get ionized. But the triangular cavity at top was made by the cluster.

• Are you sure https://apod.nasa.gov/apod/ap180801.html

Pretty sure...

• https://apod.nasa.gov/apod/ap180801.html

Chris Peterson wrote: ↑Sun Sep 05, 2021 1:28 pm

johnnydeep wrote: ↑Sun Sep 05, 2021 1:06 pm

Ann wrote: ↑Sun Sep 05, 2021 4:36 am
Victor, I was impressed by your colored squares. I can see that you used black squares and placed color hex markings around them.

But where did you find the black squares? I would love to use them, too!

Ann

I'm not Victor, but I thought they might just be unicode characters. His "square" is really two chars side-by-side. I thought they might be one of the "geometric shapes" shown here - https://www.unicodepedia.com/groups/geometric-shapes/ - but none exactly match what Victor used. Though the "black vertical rectagle" comes close: ▮, but it's not big enough! Can it be colorized with the "font color" tool in the post editor? Let's see: ▮▮▮. Yup! But there is also space between successive chars, which Victor's double black box chars don't have. I still suspect it's a unicode char however.

Sure. You can just look at it in the quoted text. It's Unicode U+2588, Full Block. In Windows you type it using ALT-219 (█) or a pair of those (██). As an ordinary character, you can apply whatever styling BBCODE offers: █.

VictorBorun wrote: ↑Sun Sep 05, 2021 3:43 pm

johnnydeep wrote: ↑Sun Sep 05, 2021 1:46 pm But how did you determine that is was U+2588?

copy-paste the █ character from the text you see to the search window and get the page about full block (U+2588) character

VictorBorun wrote: ↑Sun Sep 05, 2021 3:43 pm

johnnydeep wrote: ↑Sun Sep 05, 2021 1:46 pm But how did you determine that is was U+2588?

copy-paste the █ character from the text you see to the search window and get the page about full block (U+2588) character

johnnydeep wrote: ↑Sun Sep 05, 2021 1:46 pm But how did you determine that is was U+2588?

Chris Peterson wrote: ↑Sun Sep 05, 2021 2:47 pm

johnnydeep wrote: ↑Sun Sep 05, 2021 2:43 pm

Chris Peterson wrote: ↑Sun Sep 05, 2021 2:30 pm
Those three bytes are the UTF-8 encoding for the Full Block character. Almost all webpages use UTF-8. My text editor, Notepad++, can show characters in most formats.

I had used Notepad++ as well, but can't find a way to display hex codes there either. Even tried installing/enabling its hex editor plug-in but that failed due to some obscure 32-bit issue that I tired of battling. Have to reinstall Notepad++ now.

Visual Studio Code (which you can install separately from Visual Studio) is also an extremely nice text editor, and one which can show hex values and common encodings.

johnnydeep wrote: ↑Sun Sep 05, 2021 2:43 pm

Chris Peterson wrote: ↑Sun Sep 05, 2021 2:30 pm

johnnydeep wrote: ↑Sun Sep 05, 2021 2:14 pm

What text editor? I had tried pasting the block into a .txt file on Windows and then using the Elvis editor (a unix Vi clone) to look at the hex codes, but ended up with the three-char 0xE29688. I guess this is some unicode encoding conversion thing going on that I don't understand.

Also, nice decoding tool!

Those three bytes are the UTF-8 encoding for the Full Block character. Almost all webpages use UTF-8. My text editor, Notepad++, can show characters in most formats.

I had used Notepad++ as well, but can't find a way to display hex codes there either. Even tried installing/enabling its hex editor plug-in but that failed due to some obscure 32-bit issue that I tired of battling. Have to reinstall Notepad++ now.

Chris Peterson wrote: ↑Sun Sep 05, 2021 2:30 pm

johnnydeep wrote: ↑Sun Sep 05, 2021 2:14 pm

Chris Peterson wrote: ↑Sun Sep 05, 2021 1:59 pm

I pasted it into a text editor and looked at the coding. There are also a ton of online Unicode decoders, like this one that you can paste a character or a string into and get the decoded version.

What text editor? I had tried pasting the block into a .txt file on Windows and then using the Elvis editor (a unix Vi clone) to look at the hex codes, but ended up with the three-char 0xE29688. I guess this is some unicode encoding conversion thing going on that I don't understand.

Also, nice decoding tool!

Those three bytes are the UTF-8 encoding for the Full Block character. Almost all webpages use UTF-8. My text editor, Notepad++, can show characters in most formats.

johnnydeep wrote: ↑Sun Sep 05, 2021 2:14 pm

Chris Peterson wrote: ↑Sun Sep 05, 2021 1:59 pm

johnnydeep wrote: ↑Sun Sep 05, 2021 1:46 pm

Thanks. That's it alright. More here - http://www.unicode-symbol.com/block/Block_Elements.html

But how did you determine that is was U+2588? How did you "just look at in in the quoted text"? In my browser reply window it still shows up as a black block.

I pasted it into a text editor and looked at the coding. There are also a ton of online Unicode decoders, like this one that you can paste a character or a string into and get the decoded version.

What text editor? I had tried pasting the block into a .txt file on Windows and then using the Elvis editor (a unix Vi clone) to look at the hex codes, but ended up with the three-char 0xE29688. I guess this is some unicode encoding conversion thing going on that I don't understand.

Also, nice decoding tool!

Chris Peterson wrote: ↑Sun Sep 05, 2021 1:59 pm

johnnydeep wrote: ↑Sun Sep 05, 2021 1:46 pm

Chris Peterson wrote: ↑Sun Sep 05, 2021 1:28 pm

Sure. You can just look at it in the quoted text. It's Unicode U+2588, Full Block. In Windows you type it using ALT-219 (█) or a pair of those (██). As an ordinary character, you can apply whatever styling BBCODE offers: █.

Thanks. That's it alright. More here - http://www.unicode-symbol.com/block/Block_Elements.html

But how did you determine that is was U+2588? How did you "just look at in in the quoted text"? In my browser reply window it still shows up as a black block.

I pasted it into a text editor and looked at the coding. There are also a ton of online Unicode decoders, like this one that you can paste a character or a string into and get the decoded version.

johnnydeep wrote: ↑Sun Sep 05, 2021 1:46 pm

Chris Peterson wrote: ↑Sun Sep 05, 2021 1:28 pm

johnnydeep wrote: ↑Sun Sep 05, 2021 1:06 pm

I'm not Victor, but I thought they might just be unicode characters. His "square" is really two chars side-by-side. I thought they might be one of the "geometric shapes" shown here - https://www.unicodepedia.com/groups/geometric-shapes/ - but none exactly match what Victor used. Though the "black vertical rectagle" comes close: ▮, but it's not big enough! Can it be colorized with the "font color" tool in the post editor? Let's see: ▮▮▮. Yup! But there is also space between successive chars, which Victor's double black box chars don't have. I still suspect it's a unicode char however.

Sure. You can just look at it in the quoted text. It's Unicode U+2588, Full Block. In Windows you type it using ALT-219 (█) or a pair of those (██). As an ordinary character, you can apply whatever styling BBCODE offers: █.

Thanks. That's it alright. More here - http://www.unicode-symbol.com/block/Block_Elements.html

But how did you determine that is was U+2588? How did you "just look at in in the quoted text"? In my browser reply window it still shows up as a black block.

Chris Peterson wrote: ↑Sun Sep 05, 2021 1:28 pm

johnnydeep wrote: ↑Sun Sep 05, 2021 1:06 pm

Ann wrote: ↑Sun Sep 05, 2021 4:36 am
Victor, I was impressed by your colored squares. I can see that you used black squares and placed color hex markings around them.

But where did you find the black squares? I would love to use them, too!

Ann

I'm not Victor, but I thought they might just be unicode characters. His "square" is really two chars side-by-side. I thought they might be one of the "geometric shapes" shown here - https://www.unicodepedia.com/groups/geometric-shapes/ - but none exactly match what Victor used. Though the "black vertical rectagle" comes close: ▮, but it's not big enough! Can it be colorized with the "font color" tool in the post editor? Let's see: ▮▮▮. Yup! But there is also space between successive chars, which Victor's double black box chars don't have. I still suspect it's a unicode char however.

Sure. You can just look at it in the quoted text. It's Unicode U+2588, Full Block. In Windows you type it using ALT-219 (█) or a pair of those (██). As an ordinary character, you can apply whatever styling BBCODE offers: █.

johnnydeep wrote: ↑Sun Sep 05, 2021 1:06 pm

Ann wrote: ↑Sun Sep 05, 2021 4:36 am
Victor, I was impressed by your colored squares. I can see that you used black squares and placed color hex markings around them.

But where did you find the black squares? I would love to use them, too!

Ann

I'm not Victor, but I thought they might just be unicode characters. His "square" is really two chars side-by-side. I thought they might be one of the "geometric shapes" shown here - https://www.unicodepedia.com/groups/geometric-shapes/ - but none exactly match what Victor used. Though the "black vertical rectagle" comes close: ▮, but it's not big enough! Can it be colorized with the "font color" tool in the post editor? Let's see: ▮▮▮. Yup! But there is also space between successive chars, which Victor's double black box chars don't have. I still suspect it's a unicode char however.

Ann wrote: ↑Sun Sep 05, 2021 4:36 am
Victor, I was impressed by your colored squares. I can see that you used black squares and placed color hex markings around them.

But where did you find the black squares? I would love to use them, too!

Ann

VictorBorun wrote: ↑Sun Sep 05, 2021 12:20 am

Ann wrote: ↑Sat Sep 04, 2021 6:09 am the blue and cyan hues are just normal blue reflection nebulosity, caused by "forward scattering" of blue light by dust particles behind the light source. (If a substantive wall of dust is in front of the blue light source, the light will be "scattered away" by the dust, so that the shortwave blue and purple photons don't reach us.)

purple color in RGB (+Hα) photography can only ionized hydrogen along with blue reflection nebulosity.

Let's compare today's APOD with a picture that really brings out the Hα in the Iris Nebula:

The Iris Nebula. Photo: Satwant Kumar.

---

The Iris Nebula Adam Block.png

The Iris Nebula. Photo: Adam Block.

Note that Adam Block's image is "upside down" compared to Satwant Kumar's. Also note that Adam Block is clearly using an Hα filter for his image, which Satwant Kumar probably is not.

Note that the typical "background color" of cosmic dust is brown. When such dust is "neutrally illuminated" (by white light), it will look light brown and sometimes a little reddish. It can be hard to see the difference between normal illuminated dust and faint reddish Hα emission.
Ann

Wow.

But I fear I was not as clear as should.
1) Satwant Kumar's pic of Iris Nebula (in the post) shows little if any purple. Hα red glow must be too faint to notice without narrow-band filter imaging.
By the shift of the hue from blue-cyan to violet-blue I meant just usual range of cool hues ██ ██ ██ as opposed to warm hues ██ ██ ██
These are hues for monotonic spectra. There can be no green or pink; even bounding hues are impossible, that is cyan and violet around the cool range and red and yellow around the warm range, ██ ██ and ██ ██. Purple is violet-pink and a no-go as a scattering hue.

2) Dust can have a color when dust particles can partly reflect and partly absorb the illuminating light. A photon must hit the dust particle centrally or near-centrally; if a photon just brushes the edge of a dust particle it never gets absorbed, just forward-scattered a little, so the dust particle material has no chance to show its color. Gray, brown and orange dust clouds need other illumination than a point background light source <1° from the line of sight.

alter-ego wrote: ↑Sun Sep 05, 2021 12:01 am

Ann wrote: ↑Sat Sep 04, 2021 4:43 pm

neufer wrote: ↑Sat Sep 04, 2021 3:57 pm

• Are you sure https://apod.nasa.gov/apod/ap180801.html

Pretty sure:

Anne's Astronomy wrote:

The Iris Nebula (LBN 487, VDB 139 and Caldwell 4) is a bright reflection nebula some 6 light-years across and about 1,300 light-years away in the constellation Cepheus. The nebula is often mistakenly labelled for its associated open star cluster NGC 7023, which is present in the triangular “top hat” just above center in the image.

Wikipedia wrote:

The Iris Nebula (also known as NGC 7023 and Caldwell 4) is a bright reflection nebula in the constellation Cepheus. The designation NGC 7023 refers to the open cluster within the larger reflection nebula designated LBN 487.

And when I asked my software Guide to take me to NGC 7023, it clearly took me to the "top hat cavity" of the nebulosity, not to the star HD 200775.

Ann

I can't find any substantive data to support the open cluster as NGC 7023. Most hits support the nebula. The ones that ID the cluster aren't trustworthy they don't have good supporting data, or are self-inconsistent. Although "Anne" says confidently says the nebula is mistakenly ID'd, the heavy-weight reputable databases don't support that. Even the Wiki reference is not self consistent.

Searching for NGC 7023 using the best databases and search engines (NED, SIMBAD, AAS Worldwide Telescope,NGC/IC Project , VizieR, Aladin, and my 3-Volume Millenium Star Atlas), I find the ID NGC 7023 = Iris Nebula in all cases, not the open cluster. In the Wiki article, the SEDS and VizieR links list the star cluster, but I don't trust these. First, Wiki VizieR link references 4 catalogs, but only the oldest catalog (VII/1B, 1973) lists the cluster, and getting to this result is funky - If you input NGC 7023 ID, you also have to introduce a search radius large enough to overlap the cluster location. Then the result shows the new location for NGC 7023 (LIke I said, funky). The other 3 newer catalogs take you to the nebula without forcing a coordinate change via an unknown search radius. Second, I don't trust the Wiki SEDS link because several supporting links don't go anywhere, and the associated link to the Digitize Sky Survey image does not agree with survey image result made today. The present survey image shows NGC 7023 as the nebula.

Sorry Ann, I think Anne's Astronomy is lacking up-to-date data, or the rest of the databases need correcting.

Ann wrote: ↑Sat Sep 04, 2021 6:09 am the blue and cyan hues are just normal blue reflection nebulosity, caused by "forward scattering" of blue light by dust particles behind the light source. (If a substantive wall of dust is in front of the blue light source, the light will be "scattered away" by the dust, so that the shortwave blue and purple photons don't reach us.)

purple color in RGB (+Hα) photography can only ionized hydrogen along with blue reflection nebulosity.

Let's compare today's APOD with a picture that really brings out the Hα in the Iris Nebula:

The Iris Nebula. Photo: Satwant Kumar.

---

The Iris Nebula Adam Block.png

The Iris Nebula. Photo: Adam Block.

Note that Adam Block's image is "upside down" compared to Satwant Kumar's. Also note that Adam Block is clearly using an Hα filter for his image, which Satwant Kumar probably is not.

Note that the typical "background color" of cosmic dust is brown. When such dust is "neutrally illuminated" (by white light), it will look light brown and sometimes a little reddish. It can be hard to see the difference between normal illuminated dust and faint reddish Hα emission.
Ann

Chris Peterson wrote: ↑Sat Sep 04, 2021 1:11 pm

alter-ego wrote: ↑Sat Sep 04, 2021 4:15 am 2) I'm dubious of inferring any truthful scattering phenomena from the colors you're referencing in this image.

I believe this is the proper view. What we get from color here is that shorter wavelengths are scattered, we see characteristic hues of dust, and there's some luminescence. And basically, that's it. Color in images like this does not provide much more. Between the characteristics of the filters used to acquire the data, non-linear processing for aesthetics, the characteristics of our display devices, and the nature of our eyes, it simply isn't possible to use "color" to tell us very much beyond broad strokes.

Ann wrote: ↑Sat Sep 04, 2021 4:43 pm

neufer wrote: ↑Sat Sep 04, 2021 3:57 pm

Ann wrote: ↑Sat Sep 04, 2021 6:11 am
Okay, I promised you: That's star cluster NGC 7023 (top) in the Iris Nebula! The cluster is responsible for the "top hat cavity" at top.

I can see that the arrows I drew make it look as if some force is pushing the dust inwards, toward the middle. Of course, the opposite is true. It is the wind and ultraviolet light from the hot bright star that pushes the dust outwards, creating both the cavity around the star and and the edges of gas and dust that get ionized. But the triangular cavity at top was made by the cluster.

• Are you sure https://apod.nasa.gov/apod/ap180801.html

Pretty sure:

Anne's Astronomy wrote:

The Iris Nebula (LBN 487, VDB 139 and Caldwell 4) is a bright reflection nebula some 6 light-years across and about 1,300 light-years away in the constellation Cepheus. The nebula is often mistakenly labelled for its associated open star cluster NGC 7023, which is present in the triangular “top hat” just above center in the image.

Wikipedia wrote:

The Iris Nebula (also known as NGC 7023 and Caldwell 4) is a bright reflection nebula in the constellation Cepheus. The designation NGC 7023 refers to the open cluster within the larger reflection nebula designated LBN 487.

And when I asked my software Guide to take me to NGC 7023, it clearly took me to the "top hat cavity" of the nebulosity, not to the star HD 200775.

Ann