Questions tagged [observational-astronomy]
Questions about the techniques and practice of observing the night sky.
191
questions with no upvoted or accepted answers
8
votes
0
answers
117
views
Spatial wind speed distribution on Mars using dune shapes?
As a fan of exometeorology (the study of atmospheres of other planets), I scanned through a whitepaper Measuring Mars Atmospheric Winds from Orbit which says
Measurements of Mars
atmospheric winds ...
- 5,304
6
votes
0
answers
112
views
If I can't unscramble an egg, how do Astronomers unscramble views gravitationally lensed by complex mass distributions?
Quanta Magazine's Two Weeks In, the Webb Space Telescope Is Reshaping Astronomy highlights two submissions to arXiv soon after the first images were released: "Three days later, just minutes ...
- 31.8k
6
votes
0
answers
182
views
How exactly was Giovanni Cassini able to measure the distance to Mars?
Recently learned that Cassini was able to calculate the distance to Mars quite well using parallax in 1671. I was surprised, since even at opposition of Mars, the parallax (with respect to the Earth's ...
- 1,452
5
votes
0
answers
66
views
Angular resolution of naked eye at night; type of vision used
It appears that most sources quote the angular resolution of the eye as 1', regardless of day and night.
For instance,
Naked eye
Seconds of Arc and the Unaided Eye
However, the following websites give ...
- 193
5
votes
0
answers
77
views
What about the U planet?
In 2014 and 15, an object called U has been detected by the ALMA in Chile, considered likely to be a super-Earth at 300 AU, among other options. Is it located where the hypothetical super-Earth ...
- 1,538
5
votes
0
answers
77
views
Is the discovery of a "mass gap" black hole by this tiny telescope just plain luck/serendipity or could it be the first of many similar discoveries?
The Kilodegree Extremely Little Telescope is a pair of modest lenses with high quality medium format CCDs attached sitting on oversized mounts in Arizona and Sutherland.
These very modest instruments ...
- 31.8k
5
votes
0
answers
107
views
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&...
- 151
5
votes
0
answers
173
views
How far have stars been seen beyond the center of the Milky Way?
What lies near the center of the galaxy is of great interest and in recent times the motion of dozen(s) of stars at the center of our galaxy orbiting around Sgr A* have been measured in great detail. ...
- 31.8k
5
votes
0
answers
70
views
Are occultation observations used/useful for orbit determination?
The IAU Minor Planet Center lists $(486958)\space 2014 \space MU_{69}$ "Ultima Thule" as having an uncertainty parameter of 2, based on the observation arc of 851 days, from its discovery in 2014, to ...
- 201
5
votes
1
answer
382
views
Could non-supernova carbon, oxygen, or silicon flashes be observed?
I was reading about the helium flash, the short but sudden onset of helium fusion in certain red giant stars. As I understand, the upper (nondegenerate) layers of the star absorb the energy as they ...
- 34.1k
4
votes
0
answers
55
views
If you could get up close to them, what nebulae would be the most visually impressive to your naked eye?
Pop cult sci-fi movies like to show nebulae as they appear in photographs, but to a live, real-time viewer: these dazzling, snazzy and amazing backdrops to spaceship flying in front of them in real-...
- 1,066
4
votes
0
answers
74
views
A new (radio) neutrino telescope in Greenland?
I just stumbled upon ScienceMag news from July 14th, 2021 which says:
By placing hundreds of radio antennas on the ice surface and dozens of meters below it, they hope to trap elusive particles known ...
- 5,304
4
votes
0
answers
63
views
Explain as simply as possible how the Sunyaev-Zeldovich (SZ) effect is used to estimate the Hubble constant
The Sunyaev–Zeldovich effect (SZ effect) is useful in determining the Hubble constant because it is independent of the cosmic distance ladder. This effect occurs when CMB (cosmic microwave background) ...
- 1,051
4
votes
0
answers
116
views
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 ...
- 31.8k
4
votes
0
answers
68
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 ...
user38152
4
votes
0
answers
69
views
What exactly would the resolution of an exoplanet hypothetically imaged by using the Sun as a gravitational lens be?
This video talks about how by sending a spacecraft to around 600 AU and beyond, we would could use the Sun as a gravitational lens and take clear detailed images of exoplanets light-years away.
What ...
- 2,222
4
votes
0
answers
72
views
From what distance could the Sun's planetary nebula be seen entirely with free eye?
When collapsing to a white dwarf, a red giant Sun would emit a planetary nebula. How far from the Sun would that nebula stretch at most?
Also: At about what distance could you see the planetary nebula ...
- 473
4
votes
0
answers
56
views
Is it possible to use something besides emulsion to directly record the image of a nighttime object using a telescope?
The following questions have got me thinking.
Is it possible to use Photolithography for telescope image sensor?
Fresnel lenses for a makeshift Galilei telescope?
Has anyone ever tried to make a ...
- 31.8k
4
votes
0
answers
38
views
K-correction vs resizing photometric bands
Is there a difference between a K-correction (see Wiki https://en.wikipedia.org/wiki/K_correction) and simply "resizing" the bands, e.g. the 2-10 keV x-ray band, with the redshift? I've read ...
- 1,075
4
votes
0
answers
125
views
Deciding optical factors between a refractive and reflective space telescope optics as a function of aperture? (visible light)
Reading Yale News' Lighting a path to Planet Nine:
To detect objects that are otherwise undetectable, Rice and Laughlin employ a method called “shifting and stacking.” They “shift” images from a ...
- 31.8k
4
votes
0
answers
82
views
How did Michelson measure the diameters of jupiter's moons using optical interferometry?
In Betelgeuse: How its Diameter was measured (Chant, C. A., Journal of the Royal Astronomical Society of Canada, Vol. 15, p.133, Bibliographic Code: 1921JRASC..15..133C) the author says:
The paper in ...
- 31.8k
4
votes
0
answers
112
views
Longest time after an image was taken when a new solar system body was discovered from it?
This answer to If there's nothing special about Pluto, why was it discovered so early? says:
In fact, often objects are discovered to be in pictures from long ago, such as Orcus, discovered in 2004, ...
- 31.8k
4
votes
0
answers
44
views
In the JPL small body browser, why is uncertainty on absolute magnitude "N/A"?
In the JPL small body browser, orbital elements are all provided with uncertainties and even a covariance matrix, such as for 2013 LA2. Very good. But underneath, the absolute magnitude is reported ...
- 1,903
4
votes
0
answers
83
views
Infrared telescopes, magnitude and observations
Currently 22-23 magnitude could be the limit to make a spectrum for ground based 10m class telescopes, 21-22 magnitude may be easy for them.
4m class telescopes could possibly handle 20 magnitude, I ...
- 2,955
3
votes
0
answers
54
views
How are plage regions related to the density of medium and velocity FeII ions?
During a literature review (abstract), I found that the intensity of FeII (298.5 nm) ions in the last solar minimum was higher than the two previous solar minima 21 & 22. The velocity of FeII ions ...
- 191
3
votes
0
answers
37
views
Is the Arid meteor shower the first to be discovered photographically?
@planetmaker's answer to How can Mercury's sodium tail be imaged? links to Ciel et Espace (Sky and Space) and browsing through I found this tantalizing beginning of an article (reading the rest ...
- 31.8k
3
votes
0
answers
26
views
How to find x-values of fourier-transformed correlation functions in velocity space?
I am trying to extract the kinematic parameters (rotation velocity, velocity dispersion, ...) of an elliptical galaxy by extracting the kinematical broadening function using the FCQ-Algortihm first ...
- 389
3
votes
0
answers
113
views
How to remove redshift from galaxy spectra in Python?
Hello I extracted a spectrum from the central region of the 2D spectrum of the major axis from NGC 4697 (I just took a central row in the 2D data set, see this question for more information: How to ...
- 389
3
votes
0
answers
45
views
Can we use asteroseismology to study neutron stars?
Asteroseismology study the propagation of sound waves inside a star to probe its internal structure. Could something similar be used to study the structure of neutron stars and put constraints on the ...
- 3,840
3
votes
0
answers
40
views
Estimate the shape of an object based on flux curve
Is there an aproximation to know the shape of a dust cloud,etc based on the magnitude/flux curves of stars they transit? Example, can I know if the shape is (at least in 2 dimensions) elliptical, ...
- 31
3
votes
0
answers
70
views
Reference request (explaining) how optical correlators combine light from multiple telescopes to produce ultra-high resolution interferometric images?
This is a reference or resource-request because it may be too challenging to explain in an answer post, but if you'd like to attempt a short summary as well, that will be great!
I have a basic ...
- 31.8k
3
votes
0
answers
54
views
Is it Possible to Calculate The Centre of Mass of the Visible Universe?
It is easy to deduce that we appear to be at the centre of the visible universe, assuming the visible universe is approximately isotropic and homogeneous in all its properties, including expansion ...
- 139
3
votes
0
answers
47
views
Flickering and noise
I'm working with flickering measures from some stars. So, I take differential magnitudes, make a histogram and fit their standard deviation. My measure of flickering is the FWHM (full width at half ...
- 31
3
votes
0
answers
31
views
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 ...
- 5,304
3
votes
0
answers
77
views
New method for exoplanet detection based on iridescence?
Could it be possible to detect exoplanets that have an abundance of iridescent minerals by analyzing their star's spectra over time as the angle in observation would lead to changes in absorbed ...
3
votes
0
answers
69
views
How often are electron-multiplying CCDs used in telescope focal planes? Will Nancy Grace Roman be the first use in a space telescope?
Section I. of The Wide Field Infrared Survey Telescope: 100 Hubbles for the 2020s says:
Table 1 summarizes the WFIRST instrument suite, and Figure 1 presents the effective area of the Wide Field ...
- 31.8k
3
votes
0
answers
48
views
Salary of observatory worker?
I am thinking of becoming an astronomer becuase I love looking through my telescope at night, and may want to make it my profession. Is there money to be made working at an observatory, or is the BLS ...
- 131
3
votes
0
answers
84
views
How were "microshutters" or other multiplexed or multi-object techniques first used in Astronomical spectroscopy?
This answer to How will microshutter arrays be used in the James Webb and future space telescopes? explains how multiple objects can be selected so that the throughput of a spectrometer can be ...
- 31.8k
3
votes
0
answers
53
views
Hello again, Barlow Lenses
I am debating if I should buy a 2x Barlow Lens. My telescope, a go-to Meade star navigator, has an aperture of 114mm, focal length of 1000mm and I currently have a 9 and 26mm eyepieces. I want to see ...
- 57
3
votes
0
answers
58
views
Detect sources near image edge with python photutils
As my question suggests, I 'm trying to use a python library photutils in order to detect sources from MUSE cube. MUSE (Multi Unit Spectroscopic Explorer) is an ...
- 131
3
votes
0
answers
60
views
Short term changes in celestial coordinates of stars
The right ascension and declination of stars change on a day to day basis. Some of the changes are quite large. The right ascension of Polaris, for example, changes by more than a degree over the ...
- 1,258
3
votes
0
answers
156
views
What does "GPU-accelerated butterfly matched filtering over dense bank of time-symmetric chirp-like templates" mean? (GW170817)
A new analysis of gravitational wave (and other data) from GW170817 on 2017-Aug-17 has been published, strongly suggesting that the merger of two neutron stars resulted in a large, rapidly rotating ...
- 31.8k
3
votes
0
answers
72
views
Creating planispheres from the perspective of nearby objects
I'm attempting to create a set of [reasonably] astronomically accurate planispheres from the perspective of observers positioned at the north or south poles of various nearby celestial objects. So ...
- 31
3
votes
0
answers
58
views
Linear motion in the equatorial frame
I would like to calculate how the RA/Dec changes when an object has an apparent linear motionin the equatorial sphere. For example, more or less what an artificial satellite would do in a circular ...
- 131
2
votes
0
answers
128
views
What is the large dim feature near the center of the first James Webb image (of SMACS 0723)?
I was intrigued by the large dim feature (highlighted below) in the center of the first James Webb image of SMACS 0723. Is anything known about it?
- 223
2
votes
0
answers
18
views
LSR and peculiar motion corrections to RAVE survey velocities
I am working towards getting a bunch of halo stars in our galaxy for my thesis. I am doing this with the help of a Toomre diagram and I am stuck. I am using the RAVE survey in conjunction with Gaia as ...
2
votes
0
answers
76
views
History, significance and "drama" (if any) of T-Tauri stars, especially the early bits?
In this answer to Can I write a systematic review as an undergraduate and get it published in a journal? in Academia SE I recounted my memory of an experience from circa 1980:
I had an initially ...
- 31.8k
2
votes
0
answers
86
views
Azimuth and Altitude angle between two points in the sky
I want to know how to correctly calculate altitude and azimuth difference, separately, between two points in the sky. The same way will be with icrs coordinates.
For the altitude difference, I simply ...
- 161
2
votes
0
answers
46
views
How exactly does SPHEREx implement 96 spectral bands with a linear variable filter across its focal plane?
JPL's mission page for SPHEREx says:
The mission will create a map of the entire sky in 96 different color bands, far exceeding the color resolution of previous all-sky maps.
Wikipedia's SPHEREx ...
- 31.8k
2
votes
0
answers
50
views
Metric to estimate measuring accuracy
I need help/suggestions on which metric/approach to use.
I am trying to estimate pointing precision by measuring the offset of the experimentally measured values from the real, theoretical values, ...
- 161