Questions tagged [observational-astronomy]
Questions about the techniques and practice of observing the night sky.
1,116
questions
1
vote
1
answer
41
views
What is a photoelectric scanner?
I am reading this article by Wing, Peimbert and Spinrad, where they mention the use of a photoelectric scanner. By searching online, I find that photoelectric scanners are used to scan punchcards, ...
- 16.8k
0
votes
0
answers
46
views
Weird object seen moving through space binoculars (irregular pattern) [duplicate]
I was looking up to the western sky with some very high powered binoculars. I am just grooming the sky looking at things I cannot see with my naked eye. I then run into this box like constellation ...
1
vote
1
answer
59
views
Why would radio astronomers choose ¹³CO and C¹⁸O spectral lines instead of the most isotopically common combination?
Wikipedia's T Tauri explains that this system is an atypical example of T Tauri stars.
It says:
As typical for the young stars, all three stars of T Tauri system are surrounded by a compact disks ...
- 32.4k
12
votes
2
answers
2k
views
How do we know that objects that appear in duplicate or triplicate, etc. due to strong gravitational lensing aren't actually multiple objects?
If we are looking at faraway objects, there is no parallax view, correct?
So isn't there a chance that an object that appears multiple due to strong foreground gravitational lensing is actually ...
- 3,729
10
votes
2
answers
2k
views
How big would a telescope have to be to get a good look at the nearest neutron star?
It's my understanding of observational astronomy that the size of a telescope limits its effective angular resolution, which is why scientists needed to use radio telescopes all over the globe to look ...
- 1,628
1
vote
0
answers
16
views
How does one think about optical depth in the context of gravitational microlensing? Is it measured or deduced from observations? Used for planning?
This excellent answer to Which studies prior to 2018 "claimed to find evidence of extragalactic planets in the Andromeda galaxy"? Which instrument was used? introduces the technique of "...
- 32.4k
3
votes
1
answer
115
views
Have interference effects (in space) ever been observed by a single instrument, as opposed to interferometry?
Not asking about:
Interferometry can be done with multiple instruments who's light paths or signals are combined interferometrically, or even between different parts of a single aperture, e.g.
What ...
- 32.4k
1
vote
2
answers
61
views
Looking for an interactive star chart
First, apologies; I understand this is like a software request over at Stack Overflow.
I'm looking for a star chart for a friend that likes to stargaze while in his outdoors hot tub. He is at latitude ...
- 111
2
votes
1
answer
127
views
When will Alpha Centauri A and B overtake Proxima Centauri as the closest stars to us?
There are 3 stars in the Alpha Centauri system: 2 large stars orbting around each other (A & B) and a distant Proxima Centauri (C) orbiting around both.
Right now it just happens that Proxima ...
- 2,222
1
vote
1
answer
51
views
Which studies prior to 2018 "claimed to find evidence of extragalactic planets in the Andromeda galaxy"? Which instrument was used?
After the first round of popular news items about the "first extragalactic exoplanet" discovery, CNET's Did astronomers find the first planet outside of the Milky Way? It's complicated ...
- 32.4k
1
vote
0
answers
30
views
Which University of Oklahoma research purported to "detect thousands of extragalactic planets back in 2018"? Which instrument was used?
After the first round of popular news items about the "first extragalactic exoplanet" discovery, CNET's Did astronomers find the first planet outside of the Milky Way? It's complicated ...
- 32.4k
6
votes
2
answers
91
views
After only one eclipse of its X-ray bright primary, how can astronomers estimate the first extragalactic exoplanet's period to be about 70 years?
Phys.org's Astronomers may have discovered the first planet outside of our galaxy links to Di Stefano et al. 2021 A possible planet candidate in an external galaxy detected through X-ray transit (...
- 32.4k
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 ...
- 32.4k
1
vote
0
answers
27
views
balmer alpha , beta line intensity [closed]
In different temperature environments, the intensity of the Balmer lines is determined by the Saha equation and the Boltzmann equation.
What I'm curious about is as follows. How can we measure the ...
- 53
-4
votes
2
answers
152
views
Telescope/s functioning from underground mines
Theoretically and Practically,
Can a Telescope function for the astronomer observed from underground mines? By "telescope" I mean the instrument used by astronomers to observe stars, planets ...
- 163
2
votes
2
answers
163
views
By type, how far out do we have good star maps?
First off, these questions asked by others seem related, but each asks a slightly different question and neither have very good answers:
How well have we mapped our local neighborhood of stars?
...
- 243
-1
votes
1
answer
58
views
What is the 'AT' astronomical catalogue? And the 'TXS' one? As in AT2019dsg and AT2019fdr?
I cannot find a site stating what the AT or TXS star/astronomy catalogues are, even though some AT and TXS 'events' have been in the news lately....
- 3,729
0
votes
1
answer
43
views
What is Hubbles WFC3 "UVIS 47 G200" filter? What is it used for? How to find an example?
Extensive reading for Are the dispersion directions of the prism and the grating in Hubble WFC3 UVIS G280 perpendicular? Can we call this a "grism"? With cross-disparsion? led me to ...
- 32.4k
2
votes
1
answer
106
views
Are the dispersion directions of the prism and the grating in Hubble WFC3 UVIS G280 perpendicular? Can we call this a "grism"? With cross-disparsion?
Prologue
From Into the UV: A precise transmission spectrum of HAT-P-41b using Hubble's WFC3/UVIS G280 grism:
The UVIS grism, however, comes with several quirks that make it difficult to observe with ...
- 32.4k
5
votes
1
answer
110
views
Sudden spikes on the light curve of a Quasar from K2 mission
I obtained the optical light curve of 3C 273 QSO from the MAST repository off the K2 mission and plotted it by making the FITS into a CSV file through Pandas dataframe and plotting the obtained ...
- 165
3
votes
2
answers
95
views
Which Venus scientists discovered the hole in the ozone layer?
After 21:00 in Venus: Earth’s Evil Twin or Just Misunderstood? (live public talk) from the JPL YouTube channel the person being interviewed "Sue Smrekar, Rocky ...
- 16.8k
3
votes
1
answer
220
views
Why is the Nancy Grace Roman Space Telescope's field of view shaped like a PacMan "ghost"?
The Curious Droid YouTube video NASA's Mega Hubble - The Roman Space Telescope illustrates the shape of the telescope's field of view and the outline has a smile or frown shape. For whatever reason it ...
- 32.4k
2
votes
0
answers
58
views
Farthest observed protoplanetary disk observed at radio frequencies? Catalog
This could be a naive question or maybe too easy to solve (I do not really know!).
Brief context: I'm interested in a certain planetary system at $d \sim 300 \, \mathrm{pc}$. It would be really nice ...
- 533
6
votes
1
answer
81
views
Why Nyquist Sampling Rate depends on Bandwidth and not max frequency?
Is the Nyquist sampling rate same for different bands if those bands have same bandwith? E.g. Would the Nyquist Sampling rate be same for 1000-1400 MHz band as for 100-500 MHz band because both the ...
- 121
3
votes
1
answer
64
views
Shortest and longest wavelengths at which exoplanets have been resolved from their primaries?
Phys.org's Radio signals from distant stars suggest hidden planets summarizes the Nature Astronomy paper The population of M dwarfs observed at low radio frequencies (also in arXiv) but this is an ...
- 32.4k
2
votes
1
answer
51
views
Obtaining the Flux-Time plot for a Quasar
As a follow up question to Obtaining the Light curve of a a Quasar, I wish to know how to obtain a Light curve for a quasar observation like this data set over here.
Is there an archival repository ...
- 165
6
votes
1
answer
274
views
rms noise, confusion and dynamic range in radio images
I have been trying to understand imaging in radio astronomy. Below are some of my questions related to it and my understanding of their answers. I am not very confident about my understanding of them ...
- 121
6
votes
0
answers
177
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
4
votes
1
answer
295
views
Why was there a gap in exoplanet detection in 2015?
The question How has the number of known TNOs evolved over time? contains a link to this image:
Number of extrasolar planet discoveries per year through April 2018, with colors indicating method of ...
- 1,342
5
votes
2
answers
201
views
Can Mercury be seen from the 60th parallel north on Earth? Shetland, Faroe, Norway, St Petersburg, Alaska
I'm originally from a city in Spain which is 40 degrees north, and I used to watch Mercury (naked eye and telescope) every time I had the opportunity, that is, when Mercury was at maximum elongation ...
- 295
0
votes
0
answers
72
views
How exactly does NEOSTEL's fly's eye telescope's secondary mirror array split the primary beam among sixteen cameras?
Wikipedia's NEOSTEL says:
The Near Earth Object Survey TELescope (NEOSTEL - also known as "Flyeye") is an astronomical survey and early-warning system for detecting near-Earth objects sized ...
- 32.4k
6
votes
1
answer
130
views
How does the Hubble Space Telescope measure the speed of the wind inside Jupiter's Great Red Spot?
Space.com's Jupiter's winds of change show increased storm speeds in Great Red Spot and Hubblesite.org's Hubble Shows Winds in Jupiter's Great Red Spot are Speeding Up both link to the recent open ...
- 32.4k
2
votes
1
answer
244
views
Query Gaia by star name
I am attempting to query Gaia programmatically in python to get certain properties for specific stars. I can write a query which obtains some properties, but only for all stars, not a set of stars or ...
1
vote
0
answers
32
views
How to calculate S/N in galaxy absorption spectra?
I want to calculate the S/N of an galaxy absorption spectrum.
I therefore chose a part of the spectrum which contains very little to none absorption features and should be only made up of noise and ...
- 359
5
votes
1
answer
360
views
How was the recently publicized Hubble image of a distant galaxy showing clearly resolved lensed in an Einstein ring produced? When was it produced?
The 24-Sep-2021 NASA Goddard video Einstein Ring Spotted by Hubble and it's Goddard Media Studio's page Einstein Ring Spotted By Hubble discuss the image, but don't really give credit to how it was ...
- 32.4k
0
votes
2
answers
266
views
Was the Nobel prize for gravitational waves handed out based on a hand-drawn theoretical curve? Has the data been fit more rigorously now?
In Sabine Hossenfelder's November 2019 video "Have we really measured gravitational waves?" (transcript, video), Sabine mentions the now famous image of the generally agreed-upon-to-be-very-...
- 32.4k
8
votes
2
answers
422
views
Is Carl Sagan's famous "snowflake" quote correct?
“The total amount of energy from outside the solar system ever received by all the radio telescopes on the planet Earth is less than the energy of a single snowflake striking the ground.”
― Carl Sagan,...
- 303
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 ...
- 359
1
vote
0
answers
36
views
What kind of space telescope could best take advantage of orbiting far from the Sun?
While Hubble has provided an astounding amount of science from low Earth orbit, one of the reasons it was put in LEO was to be readily accessible for service and upgrades by the Space Shuttle.
JWST ...
- 32.4k
4
votes
2
answers
2k
views
How can we know if a star which is visible in our night sky goes supernova?
Let's say there is a star about 3000 light-years away from earth visible in our night sky. If this star were to go supernova tomorrow(not relative to earth's night sky), we would know about it 3000 ...
23
votes
1
answer
6k
views
Why can't observatories just stop capturing for a few seconds when Starlink satellites pass though their field of view?
Given that the positions and trajectories of the Starlink satellites are public, why can't the telescopes just ignore the photons they receive when the satellites pass through the field of view?
It ...
- 331
1
vote
0
answers
25
views
Curated dataset of labelled images for NEO detection
I am looking for a dataset of images. Some images should contain NEO's (1 or more), others should not. With the dataset, there should also be an accompanying file, of which should contain 'labels'. ...
- 171
3
votes
1
answer
94
views
How, precisely, do radio astronomers detect (and record) the phases of waves for interferometry?
Interferometry is always in the news, and at radio frequencies it has been for a long time...
The popular press always talks about directly 'interfering' two waves as they come in, but can they tell ...
- 3,729
2
votes
1
answer
434
views
Why would a quantity like the 'Hubble contrast' be squared, then have its square root taken?
From Sabine Hossenfelder's recent video, New Evidence AGAINST Standard Cosmology:
And her source....
Figure 2. The variation with increasing void radius of the variance of the Hubble parameter, the ...
- 3,729
3
votes
0
answers
111
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 ...
- 359
2
votes
1
answer
52
views
How to calculate an infrared SED from the specific intensities?
I have values of total infrared fluxes (SED) in literature expressed in Jy (Jansky) for galaxies. I want to assure that my infrared radial profiles of the same galaxies in MJy/sr (and other in Jy/...
- 23
3
votes
1
answer
48
views
Optical Observation Calls: How and Where to apply for optical observations?
How and Where to apply for optical observations to support a research project?
I'm involved with research in multifrequency astrophysics and my next project will demand optical (spectroscopy) ...
- 139
5
votes
1
answer
602
views
What two "little observatories" run by a university in Chile and "by Germans" are near the future site of the Extremely Large Observatory?
Brady Haran is known for the Numberphile and Periodic Table of Videos YouTube channels but also does Deep Sky Videos.
In the video for the Extremely Large Telescope Haran stands at the site of the ...
- 32.4k
0
votes
1
answer
47
views
Determining masses from radial velocity curves of eclipsing binaries
Is the statement
From radial velocities or astrometry for eclipsing binaries, one obtains masses.
wrong, because only minimal masses can be obtained?
- 347
3
votes
1
answer
82
views
What does lowercase 'beta' mean in this graph of radio-emitting galaxies?
Correlation between the mass of the galaxies (X-axis) and the difference of their radio emissions at different radio frequencies (Y-axis). Each symbol represents an individual galaxy. The image of an ...
- 3,729