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Results tagged with observational-astronomy
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user 34155
Questions about the techniques and practice of observing the night sky.
1
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475
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What do 5-sigma, r, and lowercase-delta mean in the physical descriptions of major telescopes?
The typical 5σ point-source depth in a single visit in r will be ∼24.5 (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contain …
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0
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46
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How thick are the intergalactic filaments?
Recently, in October, news came out about the faint intergalactic filaments finally being 'found'.
Then, in June, astronomers announced that these things had enough normal matter in them to solve the …
- 5,585
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1
answer
253
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What direction does 0° in the J2000 epoch point towards on January 1, 2000?
Is 0 degrees in the J2000 Epoch 'right ascension' is a line from Earth to the sun on January 1, 2000? Or is 0 degrees the direction towards the ascending node 'equinox'? Which is NOT towards the Sun …
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How do astronomers detect the 'metals' in a star? If the atoms are presumably completely ion...
Atoms and molecules usually emit their characteristic wavelengths because of the electrons' energy levels....
Do the completely ionized ('naked') nuclei absorb and/or emit EM radiation?
If so, at what …
- 5,585
3
votes
1
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164
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Why is there no Proxima 'a' planet? I'm confused about the naming convention [duplicate]
Why is there no exoplanet around Proxima Centauri designated with the letter 'a'? There is, famously, a 'b' and now a newly confirmed 'c'....
I have read that exoplanets around a star are designated …
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6
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3
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274
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How do magnetic fields mess with astronomers' observations?
Does anyone else watch 'Dr. Becky' on YouTube?
Her March 'Night Sky News' video, subtitled 'The biggest black hole burp, a wobbly Milky Way & Betelgeuse is brighter' says that...
Obviously lots of th …
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2
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1
answer
190
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Is the LSST (Vera C. Rubin) telescope going to change position every 20 or 35 seconds?
This is a very particular question, I realize, but I am still curious...
The Vera Rubin telescope is supposed to take a 15-second exposure, then take 5 seconds to move to its next spot...
But I also r …
- 5,585
2
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1
answer
88
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What do the letters WHL and LS stand for in the description and name of Earendel star, and o...
Earendel star's official name includes the abbreviations WHL and LS, as do some other very far-off objects....
What do they stand for?
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6
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1
answer
359
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If a pulsar's rotational and magnetic axes were aligned and both aimed at us, would we see a...
In other words, a non-pulsing pulsar?
- 5,585
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2
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189
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What are the effects of using non-spherical lenses in refracting telescopes?
Non-spherical (or non-circular) mirrors for reflecting telescopes are common and discussed in many places...
But what about elliptical, parabolic or hyperbolic lenses?
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119
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How can astrophysicists discriminate between pp-chain solar neutrinos and CNO-cycle ones?
Astrophysicists at the Borexino experiment in Italy have recently claimed that they have detected CNO-cycle neutrinos coming from the Sun.
It was the Cover story for the November 26 issue of Nature.
I …
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5
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1
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151
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How, exactly, does the precise measurement of the CMB's polarization modes and temperature f...
Amidst all the talk a year and change ago about the value of the Hubble parameter reached by the Planck satellite team, and how it's value differed from the value reached by the 'distance-ladder' team …
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6
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3
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183
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Do telescope measurements (in meters, usually) measure in a straight line, from edge to edge...
Somehow, no site or book or magazine has clarified this question for me....
Perhaps I am an idiot, but,
Is the parabolic primary mirror on the new James Webb Space Telescope (JWST) 6.5 meters from edg …
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2
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2
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59
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How can photoionization release photons? As in the coronal emission of a nova star?
The photoionization process absorbs energy (light), it doesn't release it....
So how can some astrophysicists say that photoionization releases the light responsible for the coronal emission of a star …
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0
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1
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87
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Are the most distant known objects in the universe more than 14 billion light years away? [duplicate]
When I hear about the most distant objects in the universe, such as the recently discovered galaxy GN-z11, their distances are usually stated to be a little under 14 billion light years away....
But, …
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