Questions tagged [observational-astronomy]

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

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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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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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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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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 expected,"...
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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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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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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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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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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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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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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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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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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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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 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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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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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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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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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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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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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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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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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 ...
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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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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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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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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. ...
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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?

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 ...
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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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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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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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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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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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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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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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How do radio astronomers avoid having their receivers burned out by ground-imaging radar from satellites?

After about 34:00 in the 9th press conference of AAS 235, radio astronomer and NRAO's spectrum manager Harvey Liszt talks about Radio Astronomy in a New Era of ...
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Simulation and its necessity in astronomical research

I was wondering if mainly everything in Astronomical and Astrophysical was dependent on Simulations then what are the educational requirements are necessary to qualify as the Simulation Expert. What ...
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“Juxtapositions” of moon,stars and planets in the sky,

What are "Juxtapositions" of the Moon, stars and planets called? When the Moon, stars and planets take exactly the same position after few or many years, how to describe the positions and what is ...
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Can a material other than glass be used for making telescope mirrors?

Although I do know of a few instances where professional or observatory mirrors have been made by alternate materials, it was primarily for targeting specific nuances, like weight reduction and low ...
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We should be seeing more than 59% of the Moon

It is said that we see about 59% part of the Moon due to libration. However we must be seeing more than that. My logic is as below. Since the Moon's orbit is inclined to the plane of Sun-Earth by 5 1/...
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When exactly star Sirius shines into the queen's chamber of Great Pyramid?

I read that Great Pyramid was built to resonate with Sirius by aligning an airshaft that connected to queen's chamber. That is, the light of Sirius going through the shaft would be able to shine into ...
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When can the Sun, Moon and the five naked-eye planets all be in Leo?

What are the possible dates for the seven (classical/mediaeval) planets (Sun, Moon, Mars, Mercury, Jupiter, Saturn, Venus) all being in Leo? I’m not sure how to figure this out on my own. I’m ...

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