Questions tagged [observational-astronomy]

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

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4
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4answers
338 views

How do focal length, angular magnification and field of view relate?

The larger the focal length the larger the angular magnification The smaller the focal length the larger the field of view. I don't understand why this applies. I'm talking specifically about ...
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2answers
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Why are Cassegrain telescopes shorter than Newtonian reflecting telescopes?

Many websites say this is because the effective focal length of the objective is increased by making the secondary mirror convex. This allows a Cassegrain telescope to be shorter than a similarly ...
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1answer
31 views

Brightness, altitude & azimuth for satellites?

I'm using the heavens-above website to identify a satellite I've seen several nights this week. The question is related to how I can search the satellites table with the information I can provide. ...
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1answer
104 views

Can the interferometer called “Gravity” measure “a few centimeters on the Moon”?

Phys.org's Very Large Telescope sees star dance around supermassive black hole, proves Einstein right links to several ESO videos, including Interview with Reinhard Genzel (in English). After ...
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1answer
109 views

How low can the sun be seen in the sky?

I'm interested in knowing how low the sun could ever get in the sky and still be seen. More technically: what's the minimum possible elevation of the sun at which it can still be seen above the ...
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0answers
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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 ...
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1answer
34 views

Calculating Field of View of a Telescope Given Time of Another Object

Given the celestial coordinates of a certain star and the time it takes to pass across your telescope's eyepiece, how can you calculate the field of view of the telescope?
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1answer
57 views

Distance to star using color index

I'm doing the following question: A star is observed with UBV magnitudes $m_u = 16.31$, $m_b = 14.52$, $m_v = 13.76$. Spectral analysis gives $M_{bol} = 7.31$, $BC = -1.02$, $(U − B)_0 = 1.222$. ...
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What is the highest redshift a galaxy with a known stellar mass can be observed?

As part of my research, I would need the following information which it seems I cannot find it in literature. I would like to know what are the highest redshifts at which $10^{7}$, $10^{8}$, and $10^{...
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Moving objects in the sky tonight 27th March 2020 [duplicate]

Multiple moving objects not in a line. The are staggered single line and in groups of two or three. One or two moved downward. They had a dim light orangey colour. It was not obvious that these ...
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0answers
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Betelgeuse problem

I've been given this problem: (a) A telescope is required to image an area of the sky of angular size 1 arc second onto a 10 mm square CCD. What focal length must the telescope mirror have to fully ...
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2answers
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Has radio astronomy ever been done on objects that appear very close to the Moon? Is this avoided?

This answer to Which kinds of astronomical observations most need to avoid the Moon being up? mentions For completeness - radio, mid-infrared and mm-wave observations are unaffected (unless the ...
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1answer
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Why were solar constant measurements before TSIS-1 all about 0.3% high?

Phys.org's Solar energy tracker powers down after 17 years says: "The big surprise with TSI was that the amount of irradiance it measured was 4.6 watts per square meter less than what was ...
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1answer
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Was the “green star” event in NGC 3314 ever figured out or named?

from NGC 3314 Variable Object by By Bill Keel (University of Alabama, Tuscaloosa) and Lisa Frattare (Hubble Heritage Project, STScI). The object in question is circled. Comments below this answer led ...
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1answer
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Can I use the parallax coefficients for observatories as a proxy for latitude using arctan2(sin, cos)?

In How are the three character IAU Minor Planet Center's Observatory Codes assigned? Why are some letters so popular? I looked at the distribution of the first alphanumeric character versus the value ...
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1answer
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Visible satellites real time position API

I'm trying to obtain the azimuth and elevation of all (or at least the majority) visible artificial satellites from a given latitude and longitude. Is there a quite stable API that does that for free? ...
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1answer
59 views

How are the three character IAU Minor Planet Center's Observatory Codes assigned? Why are some letters so popular?

Answers to Latitude, longitude and altitude of Ckoirama Observatory; where can things like this be looked-up? point to https://www.minorplanetcenter.net/iau/lists/ObsCodesF.html which currently lists ...
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Latitude, longitude and altitude of Ckoirama Observatory; where can things like this be looked-up?

This answer to Is Starlink 1130 (Darksat) really dimmer? links to the March 16, 2020 paper in arXiv First observations and magnitude measurement of SpaceX's Darksat which finds only a modest decrease ...
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2answers
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Which of the planets would be detected if they were exoplanets?

An (almost-)omnipotent being selects the solar system, presses Ctrl+C, and then Ctrl+V several times, creating copies at distances of 5, 500, 50.000, and 5.000.000 light-years away. All in a direction ...
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1answer
61 views

How to find Kepler/TESS data [duplicate]

I have some basic understanding of the Kepler/TESS mission. The missions both look at the stars and try to find the dip in the light from the stars to find possible existence of exoplanets (exomoons ...
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2answers
143 views

Which kinds of astronomical observations most need to avoid the Moon being up?

This comment to Did nobody in the Astronomy community think 12,000 new satellites in LEO might be a problem? links to Phys.org's New ESO study evaluates impact of satellite constellations on ...
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1answer
951 views

How is an exoplanet characterised as “Earth-Like”?

Which features or characteristics are taken into account to characterize an exoplanet as "Earth-Like"?
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113 views

Usefulness of the hour angle (HA)

The Hour Angle (HA) is measured west from the observer's meridian in hours, mins, seconds. How is the Hour Angle used to help plan observations during the night at a telescope?
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1answer
53 views

Continuum at 230 GHz

what does it mean 'The observations were made in the CO J=2–1 line and continuum at 230 GHz (1.3 mm)'? "The observations of the continuum were also made with a bandwidth of 320 MHz. " http://articles....
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Is 486958 Arrokoth (2014 MU69 aka Ultima Thule) the only solar-system object determined to be binary by occultation?

The asteroid 486958 Arrokoth was discovered to be binary by astronomers lugging a bunch of telescopes around (I think) camping with them. The timing offered additional astrometry for the orbit ...
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What are Stokes parameters for galaxy shapes, how do they compare to Stokes parameters in optics?

I remember Stokes parameters as a way to completely define the polarization state of a well-defined beam of light. However several questions here refer to Stokes parameters used in characterizing the ...
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Do all High-Mass X-Ray Binaries have observable supernova remnants surrounding them?

I am studying high mass X-ray binaries, which are star systems that generally contain a neutron Star orbiting a larger companion. My assumption is that such systems began as two typical stars in ...
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1answer
106 views

Why does moon moves to side if I change my position directly into it?

I've setup this scenario on Stellarium where the moon is aligned with East direction. I wanted to see the change of altitude of the moon if I move straight into its direction (time of observation is ...
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1answer
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What is a “21cm/mm absorption system” in the context of measuring old photons from quasars?

This answer links to Wikipedia's Time-variation of fundamental constants which cites Further Evidence for Cosmological Evolution of the Fine Structure Constant (J. K. Webb et al. 2001), the abstract ...
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Why do all the stars near this comet show up as four separate dots in a row?

After seeing this tweet about our not-so-new but at least newly-discovered "mini-moon" I scrolled down and saw the tweeted image below. Since the object is the known short-period comet 114P/Wiseman–...
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1answer
92 views

The goblin furthest [closed]

I just watched a documentary last night that stated a new discovery was so far away in our solar system the Hubble could only show it as a few blurred pixels, Robert Fosbury narrated and it was called ...
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1answer
412 views

Have there been studies of “old photons” to see just how constant things like Planck constant has been?

The question Are photons aged? and answers therein have got me thinking: I vaguely remember hearing something about experiments where "old photons" were collected by large telescopes from very ...
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3answers
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Is Hawking radiation detectable?

Could Hawking radiation be detected with instruments available today? If not, what sort of instruments would be required to observe it? Would there be any way to confirm through observations the ...
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1answer
65 views

How can a star's rotation speed be measured?

How can a star's rotation speed be measured? If stars could be resolved, then you could use the Doppler shift to see that half of the star is bluer and the other half is redder, but stars (other ...
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1answer
5k views

How can a mirror see things that the naked eye can’t?

How does a mirror pick up light from vast distances away? And, if that light can reach a mirror, why can’t we see that light?
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1answer
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Does this CHEOPS first light image imply bad astronomy?

@KeithMcClary's comment under lousy mirror corrected by software links to Bad Astronomy's First Light for the Exoplanet Hunter Mission CHEOPS Goes Tetrahedral which shows the image below. I understand ...
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1answer
56 views

Why do radio telescopes, but not shorter wavelengths, have this Big Data problem?

Only with new radio telescope arrays like ALMA and SKA, have I heard of this "problem" with too much data come up. Too big to store. That one cannot archive it all for future studies, but that one has ...
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0answers
58 views

Field rotation and observing the moon

For stars, field rotation can be accounted for with an equatorial mount aligned with the Earth's axis and turning at the correct rate. Since the Moon's orbit is on a different axis then the Earth's ...
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2answers
103 views

What was the field of view of the Ohio State University Radio Observatory of Wow! signal fame?

This answer to Did comets 266P/Christensen or P/2008 Y2 (Gibbs) cause the Wow! signal? points out that the comets in question were nowhere near where the radio telescope was pointed. Wikipedia says ...
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1answer
83 views

Can the WISE telescope detect black holes?

Black holes are hot, aren't they? With its infrared scan, could the WISE telescope also detect a black hole? The hypothetical planet beyond the Kuiper belt could actually be a primordial black hole. ...
2
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1answer
155 views

Precision in the measurement of the distance to the Sun

How precisely can the distance to the Sun be measured? Wikipedia says the distance to the Moon can be measured upto millimeter precision. But Wikipedia article on distance to the Sun says only about ...
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What book(s) should I read to get started learning about astronomy? [duplicate]

I'm an undergrad software engineer but I also love physics and math. I'm starting to get going in AI/Machine Learning techniques and I'm going to use NASA data-sets to conduct analysis. However, I am ...
2
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1answer
65 views

How to install Distro Astro operating system?

I've recently started a project on Galaxy spectroscopy for which I had to use IRAF software. During the search for IRAF software, I came across a platform which said that Distro Astro is a very good ...
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1answer
69 views

What could I resolve with my Telescope

I recently won a Common 50mm refracting telescope with Solar Filter too.. I'm trying to Understand things I can skygaze with it. It's pretty basic and I should have known. Unfortunately, I don't ...
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1answer
95 views

What observational data convinced Stephen Hawking that Cygnus X-1 was indeed a black hole and caused him to break into Kip Thorne's office?

It's generally easier to be certain an object is a star than a black hole. HDE 226868 is one of our site moderators and a blue supergiant star. The latter has a 5.6 day companion that supplied a ...
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1answer
133 views

At what distance does Proxima Centauri become visible to the naked eye?

The red dwarf star Proxima Centauri is the closest-known star to the Sun (being about 4.2 ly or 1.3 pc away), however it's not visible to the unaided eye for it is too small and dim. I'd like to know ...
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0answers
28 views

Why does the star formation rate correlate with the total stellar mass in star forming galaxies?

The so-called "Main Sequence" of star-forming galaxies (e.g., Brinchmann et al. 2004; Noeske et al. 2007) clearly points to a linear relation between the stellar mass of galaxies and their star ...
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1answer
121 views

Would you recommend this telescope to a beginner?

Celestron Astro FI-5 125 mm f/10 Schmidt-Cassegrain with a computerized altitude-azimuth single fork mount https://www.celestron.com/products/astro-fi-5-schmidt-cassegrain-telescope https://www....
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1answer
99 views

How do they know the non-uniformities seen on the disk of π¹ Gru are real and not artifacts?

@RobJeffries' answer to What is this web on the surface of the Sun? explains why convection cells on some other stars can be far larger than they are on our Sun and includes a near-infrared VLT ...
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If I discovered a planet that has compositions not known to man and that no one else had previously discovered can I apply a patent for it? [closed]

According to legalzoom A new composition discovered can be patented, if I was to discover a planet with a new composition, would I be able to patent that planet and its compositions?

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