Questions tagged [observational-astronomy]

Questions about the techniques and practice of observing the night sky.

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9
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1answer
212 views

Can automatic algorithms completely eliminate the impact of Starlink and other satellites?

According to a comment by user @J: With that said, other than aesthetics, machine vision algorithms are wildly more advanced today than in the past - strategies to remove passing satellites don't ...
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Is the universe macroscopically transparent to CMB? Is the fraction intercepted by stars and dust so tiny that it doesn't have a correction factor?

Background The question Why do some electromagnetic waves continue travelling while others disappear? is interesting, and in addition to the answer there I started to write: This is a supplementary ...
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Why did astronomers believe most or all stellar black holes had masses no greater than 15 solar masses?

The so-called 'mass gaps' for black holes, according to theoretical models, are between 2-5 solar masses and 50 to 150 solar masses. (Actually, I have read that there is no good theoretical reason ...
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Converting Declination and Right Ascension [duplicate]

If I am been given the Right Ascension and Declination of a celestial body, how do I convert it into the altitude and azimuth as the latitude and longitude varies?
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36 views

Are astronomers still using photomultiplier tubes for optical photometry?

In Time domain astronomy and fastest eclipsing binary ZTF J1539+5027 (+20 mag, 6.91 minutes) How to measure it's minimum brightness? I've written A logarithmic magnitude scale might tend to show ...
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1answer
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Time domain astronomy and fastest eclipsing binary ZTF J1539+5027 (+20 mag, 6.91 minutes): How to measure its minimum brightness?

Per Wikipedia's ZTF J153932.16+502738.8 ZTF J153932.16+502738.8 is a double binary white dwarf with an orbital period of just 6.91 minutes. [...] The light curve shows eclipses. One dip in the light ...
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Convert apparent magnitude in a filter to a luminosity

I have data in Johnson B & V filters and I would like to convert the observed magnitudes, m$_x$, into luminosities, L$_x$, over a passband where I already know the distance, d, to the object. x is ...
2
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1answer
44 views

How can we install a radar on radio telescopes like FAST or GMRT?

Recently I came across an article mentioning that ever since the failure of Arecibo telescope, we only have one asteroid radar imaging telescope which is Goldstone observatory. The article also ...
2
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1answer
154 views

Can Hawking Radiation ever be detected and does it exist? [duplicate]

I'm researching black hole Hawking radiation for a contest, and so far I get the overall gist of how the process works. But as far as I've searched, there hasn't been any confirmed observational ...
4
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1answer
47 views

What is the significance of the velocity resolution in spectral line observations using radio interferometry?

I've always struggled to conceptualize the term "velocity resolution" in spectral observations. In principle, it is simple to calculate. For example, one can take the spectral width and ...
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sdo.gsfc.nasa.gov website offline?

Is the NASA solar dynamics website offline? If not how can the daily sun 'movies' be downloaded from https://sdo.gsfc.nasa.gov/data/dailymov.php?
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1answer
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How did I flip some mirrors around in the dark at 3 AM and change the focal length of a 24 inch Boller and Chivens?

Current answer(s) to How do telescopes "zoom" and change angle of view? are "they don't", but traditional large genera-purpose observatory telescopes do sometimes (often?) have ...
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Is there software to calculate/plot decomposed rotation curves from observational data (FITS, etc)? [closed]

I have observation data of galaxies (in FITS format). From the FITS data, I want to calculate & plot the decomposed rotation curves as pictured below. Is there a software package that will do that ...
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35 views

Can we identify planets, moons, and large asteroids in our solar system have a unique spectroscopy?

I'm looking to create a database of relatively consistent measurements for various cosmic bodies. Please inform if there's a way to gather reproducible signatures, with the same set of instruments to ...
4
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1answer
51 views

What is the significance of using baseline pairs in radio interferometry?

Radio interferometry utilizes arrays of smaller telescopes that are linked together to synthesize a larger aperture telescope. Astronomical radio observatories, such as the Very Large Array in New ...
4
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1answer
29 views

What leads an observer to choose a narrow slit over a wide one (and vice-versa) when observing?

In spectroscopy, a wide slit will lead to lower spectral resolution while too narrow of a slit will reduce incoming flux from the object. From what I read, it appears as though there is always a ...
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How to calculate the flux of a galaxy merger? [closed]

Say three galaxies, with equal fluxes, $f_1$, merge. How could I calculate their combined flux?
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2answers
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Why (the heck) is the basic angle of GAIA 106.5°?

This answer to Why does the Gaia space telescope have two main mirrors says: According to the GAIA FAQs which does an excellent job: http://www.cosmos.esa.int/web/gaia/faqs: Why is there an angle of ...
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1answer
468 views

Was GRAVITY built to look at one star?

GRAVITY (shown below) is a interferometric combiner of near infrared light from four very large telescopes called The Very Large Telescope in order to make careful astrometric measurements near the ...
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What would “the next GAIA”-like instrument be like? Could it simply be a 3 to 5x scaled-up version of the same beautiful system?

This excellent, thorough and well-sourced answer to Has a gravitational microlensing event ever been predicted? If so, has it been observed? mentions several works where hundreds to thousands of ...
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1answer
53 views

Has a gravitational microlensing event ever been predicted? If so, has it been observed?

This answer to Are astronomers waiting to see something in an image from a gravitational lens that they've already seen in an adjacent image? describes "Deja vu all over again" (SN "...
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How can the CMB have a “monopole anisotropy”?

Wikipedia's Cosmic Microwave Background (CMBR) radiation monopole anisotropy (ℓ = 0) says When ℓ = 0, the ${\displaystyle Y(\theta ,\varphi )}{\displaystyle Y(\theta ,\varphi )}$ term reduced to 1, ...
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What's the largest angle that light has been “seen to bend” by gravity? (of one object by a separate object)

Gravitational lensing is everywhere! because it falls off so slowly with $r$: $$\Delta \phi \approx \frac{4GM}{c^2r_0}.$$ That's the first order term. For a nice derivation see Viktor Toth's The ...
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Is an “observation campaign” well recognized thing in Astronomy? Is it self-declared? Are there standard ways to announce or coordinate?

The Astronomy meta question Should we have an observation-campaign tag and what is good usage advice for it? lists about 13 example questions where the tag might apply. There are several answers that ...
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Is there a collection or list of all planned observations of 99942 Apophis during its 2021 close pass to Earth?

For example, I found Goldstone Radar Observations Planning: 99942 Apophis in 2021 and 99942 Apophis 2021; Planned, Scheduled and Completed Observations at lawn.com? which seems empty. But I'll bet the ...
4
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1answer
218 views

Astrophysical black holes deviating from Kerr black holes?

Rotating black holes are formed due to the gravitational collapse of massive spinning objects. And, it is generally believed that Kerr black hole solutions are valid for the empty space outside of the ...
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45 views

Can the lensing effect of Sagittarius A* be used to image the stars diametrically opposite to the sun?

The sun can magnify an image of a source 100 ly away nearly 100 billion times, if the ring is captured from the nearest focal point (550AU). According to Christian Ready of Launch Pad Astronomy, we ...
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How can astronomers pinpoint the location of the source of a neutrino?

In the popular press, in recent months, we have heard a lot about high-energy neutrinos from far outside our solar system reaching our detectors.... But I wonder... If a single neutrino from a great ...
2
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2answers
205 views

Would it be possible to detect a magnetic field around an exoplanet?

Of course, we can't fly a magnetometer next to an exoplanet to measure the magnetic field, but might it be possible to find indirect evidence (e.g. polar auroras) of a magnetic field generated by an ...
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60 views

Strange matter objects other than neutron stars?

This question is about celestrial objects which are composed by exotic matter, and exotic matter I define as states of matter that are not commonly encountered such as Bose–Einstein condensates, ...
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Objects beyond 13.3 billion light-years away are (apparently) moving away from us at faster-than-light speeds? [duplicate]

That is, if you use the cosmic distance ladder method, and a value of about 73.5 for the Hubble constant.... But, if you plug in the Planck CMB value of about 67.5, you get a distance of about 14.5 ...
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What makes a star? [closed]

What are the properties of a star? How do astronomers classify the properties of stars?
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1answer
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Shouldn't the estimate of the universe's age be higher, not lower, after the attractive strength of gravity is taken into account?

From 'Fundamentals: Ten Keys to Reality', by Frank Wilczek : "Running the movie of cosmic history backward in our minds, we found the galaxies all coming together to meet at a definite time. ...
5
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1answer
149 views

Would it be possible to discover an asteroid belt around another star?

With existing or planned technology (e.g. the ELT or the JWST), would it be possible to infer the presence of a ring of asteroids similar to our own asteroid belt? Or would any signal be drowned out ...
5
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1answer
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What is the underlying nature of the dark spot found on Uranus?

What is the nature of bright spots found on Uranus? actually quotes Space.com's Uranus Has a Dark Spot which says: During the past decade, many bright spots have been seen on Uranus in both red and ...
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57 views

Significantly blueshifted Lyman-$\alpha$

Lyman-$\alpha$ line in galaxies is notably known to show a double peaked profile, mainly due to its scattering in a moving medium, see e.g., the very recent Matthee et al. 2021, The X-SHOOTER Lyman-α ...
4
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1answer
70 views

Can a star be massive enough to go 'supernova' yet not be massive enough to leave behind a neutron star? Or, perhaps vice versa?

From what I understand, stars that explode as a supernova at the end of their lives become either a black hole or a neutron star, and less massive stars that do not explode become white dwarves, but......
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Have there been any confirmed PISN supernovae?

I did some research on pair-instability supernovae (PISN), and wondered if there have been any confirmed superluminous supernovae caused by a pair-instability. Are there any confirmed PISNs out there, ...
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Pulsar signal periodicity detection algorithms?

I am currently working on pulsar signal periodicity detection. Most of the algorithm or paper which i read they use FFT (Fast Fourier Transform) and FFA (Fast Folding Algorithm ). Do we have any other ...
3
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2answers
45 views

Delta Velorum - non-observed variable star

I am a beginner variable star observer from the Southern Hemisphere (but with experience in astronomy) and, when I was looking for VS to observe, I saw that Del Vel has almost no observations. Thus, ...
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2answers
179 views

Sample bias' contribution to “Planet 9” hypothesis, why was this not thoroughly addressed before?

Science Claim for giant 'Planet Nine' at Solar System's edge takes a hit arXiv No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects The brightness of distant solar system objects ...
4
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1answer
49 views

Effect of particulates on the visibility of stars?

I am looking for a (mathematical) relationship - either empirical or theoretical - which quantifies how the visibility of celestrial objects decreases with increasing amount of particulates in the air....
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0answers
29 views

Convert Object Intensity to Pixel Intensity

If I have an object of some size and spectral radiance, and it's some distance R from a camera, how would I calculate its digital count value in an image? I'm sure there's an equation out there, but I ...
5
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1answer
53 views

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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1answer
58 views

Recently, the most distant object in the solar system was discovered. How was this accomplished?

It was recently announced that the most distant object in our solar system was discovered. This object averages 132 AU from the sun. The object, initially named Farfarout, was estimated to be 400 km ...
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How was the axial tilt of planets measured?

https://en.wikipedia.org/wiki/Axial_tilt#Solar_System_bodies gives the axial tilt of all planets with two decimal precision, but how and when were they measured so precisely ? I guess it's "easy&...
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0answers
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Heat map of portion of the sky visible for a given observatory on Earth?

Reading Calculating area of visible sky I started wondering which portion of the sky one could observe how long given the 3D coordinates of an observatory, and two points in time. In other words, I ...
3
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1answer
59 views

Maritime telescopes: Stabilisation requirements for optical vs. radio telescopes?

SOFIA stands for Stratospheric Observatory for Infrared Astronomy. She says: My telescope stays stable with a spherical bearing, shock absorbers, and gyroscopes. I suppose a similar system would ...
2
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3answers
75 views

What is a hard spectral state vs. a soft spectral state?

In X-ray astronomy, the source is considered to be in the hard or soft spectral state. So what is the meaning of the hard spectral state? What are the soft state and hard state in spectroscopy?
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Do higher-metallicity elliptical galaxies, that formed rapidly, have a larger velocity dispersion (lowercase-sigma)?

https://academic.oup.com/mnras/article/445/3/3092/1036122?login=true And, ..... https://www.newscientist.com/article/mg24933160-200-how-every-galaxy-comes-from-quantum-fluctuations-billions-of-years-...

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