Starship Asterisk*

by **Chris Peterson** » Sat Mar 31, 2018 2:43 pm

Oldironsides wrote: ↑Sat Mar 31, 2018 2:35 pm Hi, Chris,
I didn't think the term 'real time' needed explanation. What I meant was what you see when you look through the eyepiece of a telescope. Planetary objects like Mars, Jupiter and Saturn can be seen in color as well as some interstellar objects like the Pleiades cluster, but I happen to enjoy looking at the Orion Nebular, for instance, but in real time all I see is an image in shades of gray, not the glorious colors that appear in long exposures. The long exposures are necessary to gather greater amounts of light, and the larger the telescope equates to a shorter exposure time.

The reason "real time" needs clarification is that there's still an exposure time involved. Is a movie running at 30 frames per second "real time"? What about 10 frames per second? Anyway, modern sensors will readily show you color with 1/10 second exposures, meaning that you can reasonably see things like the Orion Nebula in color at typical video frame rates with small aperture telescopes.

By the way, your name sounds familiar. Were you ever in charge of a new Planetarium that was built in Centerport, Long Island, New York back in the 1970's? I went to Virginia City, VA to photograph the total eclipse back then and was so excited with my results I showed them to the Planetarium director who gave me a tour of the new facility.

Not me.

by **Oldironsides** » Sat Mar 31, 2018 2:35 pm

Hi, Chris,
I didn't think the term 'real time' needed explanation. What I meant was what you see when you look through the eyepiece of a telescope. Planetary objects like Mars, Jupiter and Saturn can be seen in color as well as some interstellar objects like the Pleiades cluster, but I happen to enjoy looking at the Orion Nebular, for instance, but in real time all I see is an image in shades of gray, not the glorious colors that appear in long exposures. The long exposures are necessary to gather greater amounts of light, and the larger the telescope equates to a shorter exposure time.

By the way, your name sounds familiar. Were you ever in charge of a new Planetarium that was built in Centerport, Long Island, New York back in the 1970's? I went to Virginia City, VA to photograph the total eclipse back then and was so excited with my results I showed them to the Planetarium director who gave me a tour of the new facility.

by **Chris Peterson** » Thu Mar 29, 2018 8:34 pm

Oldironsides wrote: ↑Thu Mar 29, 2018 8:26 pm On this subject, "Orion's icons don't look quite as colorful to the eye as they do to a camera." I am reminded of my favorite theoretical astronomy question. The present selection of large telescopes, even the Hubble, all have one thing in common with smaller ones, the necessity for long exposures in order to capture the true colors of the Universe.

Has anyone any idea how large a telescope would have to be to capture enough light to allow full color views in real time?

What is "real time"? Certainly, cheap video cameras running at a few frames per second produce nice color images with telescopes of only a few inches aperture.

by **Oldironsides** » Thu Mar 29, 2018 8:26 pm

On this subject, "Orion's icons don't look quite as colorful to the eye as they do to a camera." I am reminded of my favorite theoretical astronomy question. The present selection of large telescopes, even the Hubble, all have one thing in common with smaller ones, the necessity for long exposures in order to capture the true colors of the Universe.

Has anyone any idea how large a telescope would have to be to capture enough light to allow full color views in real time?

by **Boomer12k** » Thu Mar 22, 2018 4:09 am

Super Cool Image...
Clicking on the image, and going to the full page image, it looks like a DRAGON guarding its HOARD OF JEWELS...the "head" is at the bottom of the Loop...

A great full image of one of my favorite DSO's...

:---[===] *

by **rcdavison** » Thu Mar 22, 2018 3:00 am

"Orion's belt are three stars all about 1,500 light-years..." From a previous post on APOD (https://apod.nasa.gov/apod/ap171123.html) the distance of the belt stars was listed at from 800 - 1500 light-years, which coincides with an article I did showing the constellation in profile illustrating the relative distance to the constellation's major stars. (http://om-blog.orbitalmaneuvers.com/201 ... -of-orion/).

Are these distances based on new data?

Great image, by the way!

by **Ann** » Thu Mar 22, 2018 1:07 am

heehaw wrote: ↑Wed Mar 21, 2018 12:13 pm In the ultraviolet, Betelgeuse would not be there!

In a book of mine, Sky Catalogue 2000.0, volume 2, there is an early Harvard picture of Alpha and Beta Centauri and the Southern Cross. The picture was made using a blue- and ultraviolet-sensitive emulsion, meaning that blue Beta Centauri looks brighter than yellow-white Alpha Centauri. More interesting, Crux seems to miss its two "upper right" stars! Gamma Crucis, a relatively bright star (V mag 1.6), of spectral class M like Betelgeuse (although not a supergiant), is barely visible at all in the old Harvard picture. Fainter Delta Crucis ( V mag 2.7), of spectral class B2, also looks quite faint. But first magnitude Alpha and Beta Crucis, both of spectral class B0.5, emit lots and lots of blue and ultraviolet light. As a consequence, Alpha and Beta Crucis look very bright in the old Harvard photo, particularly Alpha, whereas Gamma and Delta Crucis are "missing"!

Ann

by **MarkBour** » Thu Mar 22, 2018 1:00 am

Case wrote: ↑Wed Mar 21, 2018 8:19 pm
APOD Robot wrote: ↑Wed Mar 21, 2018 4:23 amFinally, just barely visible to the unaided eye but quite striking here by camera is Barnard's Loop.
I’ve read someone claim: “Using a nebular filter held up to the naked eye can pop out several nebulae. It certainly pops the NA nebula, the Rosette, Barnard's Loop, California Nebula.”
I’ve never thought of that possibility, imagining only photographic use. Did any of you ever try naked eye nebula of Barnard's Loop brightness?

That's cool, if it works! I don't know, I guess I'd need to
spend about $80 to try the idea.

For $160, I could buy a pair and make some cosmic "rose-colored" glasses.

Here's an image grabbed from astronomy.com:
I suspect this image has been exaggerated,
but the claim still may be true enough.

by **Somebody** » Thu Mar 22, 2018 12:44 am

MikeA wrote: ↑Wed Mar 21, 2018 8:31 pm Can anyone clarify this for me regarding the resolution of photographed stars in general: Each of the prominent stars appears hazy with an apparent bright spot at the center. Is it the bright spot that delineates the star itself and if so, what constitutes the haze and why do they all have it?

All lenses reflect at least some light. A small fraction of light entering the camera lens is reflected backward. Most of that light is transmitted back through the filter, but a small percentage of it is reflected by the filter back toward the camera. Most of that light then passes through the camera lens and ends up on the detector, except now it's out of focus. Every star has these halos, but the halos are only detectable for very bright stars.

by **MikeA** » Wed Mar 21, 2018 8:31 pm

Can anyone clarify this for me regarding the resolution of photographed stars in general: Each of the prominent stars appears hazy with an apparent bright spot at the center. Is it the bright spot that delineates the star itself and if so, what constitutes the haze and why do they all have it?

by **Case** » Wed Mar 21, 2018 8:19 pm

APOD Robot wrote: ↑Wed Mar 21, 2018 4:23 amFinally, just barely visible to the unaided eye but quite striking here by camera is Barnard's Loop.

I’ve read someone claim: “Using a nebular filter held up to the naked eye can pop out several nebulae. It certainly pops the NA nebula, the Rosette, Barnard's Loop, California Nebula.”
I’ve never thought of that possibility, imagining only photographic use. Did any of you ever try naked eye nebula of Barnard's Loop brightness?

by **Sa Ji Tario** » Wed Mar 21, 2018 3:12 pm

Yes, Petrus and above is the flame nebula

by **Petrus** » Wed Mar 21, 2018 2:27 pm

Am I wrong or the small dark dot just below Alnitak is the Horsehead Nebula?

by **Sa Ji Tario** » Wed Mar 21, 2018 1:26 pm

To the right of Rigel appears the picture of my mother-in-law (nebula of La Bruja) and I continue to estimate that it is the star where Cursa ends or begins the mythical River, Eridano

by **De58te** » Wed Mar 21, 2018 1:10 pm

Yeah and don't forget a star called Saiph, aka Kappa Orionis, located in the lower left.

by **heehaw** » Wed Mar 21, 2018 12:13 pm

In the ultraviolet, Betelgeuse would not be there!

by **Ann** » Wed Mar 21, 2018 6:06 am

Don't forget the Lambda Orionis nebula at top!

Nice image.

by **APOD Robot** » Wed Mar 21, 2018 4:23 am

Camera Orion

Explanation: Do you recognize this constellation? Although it is one of the most recognizable star groupings on the sky, Orion's icons don't look quite as colorful to the eye as they do to a camera. In this 20-image digitally-composed mosaic, cool red giant Betelgeuse takes on a strong orange tint as the brightest star at the upper left. Orion's hot blue stars are numerous, with supergiant Rigel balancing Betelgeuse at the lower right, and Bellatrix at the upper right Lined up in Orion's belt are three stars all about 1,500 light-years away, born from the constellation's well-studied interstellar clouds. Below Orion's belt a reddish and fuzzy patch that might also look familiar -- the stellar nursery known as Orion's Nebula. Finally, just barely visible to the unaided eye but quite striking here by camera is Barnard's Loop -- a huge gaseous emission nebula surrounding Orion's Belt and Nebula discovered over 100 years ago by the pioneering Orion photographer E. E. Barnard.

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