Questions tagged [observational-astronomy]

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

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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 understand ...
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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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2answers
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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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1answer
161 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 ...
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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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137 views

“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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1answer
276 views

Why we can't see our Sun as it was a few years ago?

Our Sun is orbiting the center of the Milky Way galaxy. So many years ago, it was at a different location from where it is now. In addition, we are observing stars and exoplanets as they were many ...
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Saw 8 stars moving in same direction one by one [duplicate]

I saw 8 stars moving in the same direction one by one and then at the same point they faded or you can say disappear. The speed was not too fast but not too slow either. I am more curious because ...
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How is length of meridian calculated in 1793?

I was studying metrology and came across it. Kindly help me with this query? In 1793 the length of meter was realized using the length of the meridian passing through Paris divided by 10 raised to 7....
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How are small objects automatically identified and their locations determined in digital images?

I have a large quantity of old digital images of low energy electron diffraction (LEED) patterns that I must process to identify and locate small, sometimes elongated gaussian-like blobs of a few ...
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1answer
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Exposure details for this now (in)famous image from Lowell Observatory?

IAU's announcement 19035 IAU Statement on Satellite Constellations, 03 June 2019 links to 19035a Trails made by Starlink satellites which contains the image shown below. Question: Is it possible to ...
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What is the LSST now? Where does LSST end and Vera C. Rubin Observatory begin?

Space.com's It's Official: Vera Rubin Observatory Named to Honor Dark Matter Scientist says: "We're here today to focus on the major renaming of the facility after a pioneering astronomer, that ...
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How will Starlink affect observational astronomy?

I have recently found that people around the world have been posting observations of a line of moving objects in the sky which is very likely to be a part of Starlink satellite constellation, such ...
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Identifying consecutive flying objects [duplicate]

First of all, sorry for my complete lack of knowledge in the field! The event I'm describing left me puzzled and I'm looking for possible explanations, and I thought I'd start here. I saw a number of ...
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Name of extra-terrestrial “moon's” orbital period? [duplicate]

Is there a commonly used alternative to "month"? Or does that work for any moon?
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How bright is the Crab Pulsar's 30 Hz modulation in visible light? What color is it?

This answer to Has great eyesight been necessary for astronomers? mentions Astronomer Jocelyn Bell Burnell's recounting of a likely first visual observation of a pulsar. This can be found for example ...
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How can one determine the declination range of stars visible for a certain amount of time above a specific airmass at a certain location?

Let's assume you want to observe stars at Kitt Peak (32 degrees North) at an airmass above 2, for 2 hours (30 degrees of Earth rotation). My attempt: The angle between the zenith and celestial ...
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Has great eyesight been necessary for astronomers?

In a different (but somewhat related) field, some baseball stars have been known to have "baseball eyes." That is, an exceptional ability to visually follow the trajectory of a 90+ mph baseball to a ...
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Does the dimming of Betelgeuse present any observational opportunities?

Recent photometry suggests that Betelgeuse has been dimming over the past three or so months, reaching the faintest V-band magnitude seen in modern observations. The changes are apparently even ...
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How can I get the exact time of each zodiac every year?

I want to make a calculator for Chinese New Year calendar. There is a rule that a leap year happens if the eclipse happens before each zongqi (equivalent to the middle of zodiac sign, ie. 15º, 45º, ...
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How can I hear (or at least detect) a pulsar at home?

Scott Manley's video Using Relativistic Raytracing &X-Rays To See Detail on Surface Of Neutron Star talks about X-ray measurements using the NICER X-ray telescope attached to the International ...
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Anecdote of an astronomer looking for correlations in antipodal pairings of stars; what am I remembering?

The question Are the stars distributed in uniform distribution, on the celestial dome, with respect to brightness? brings to mind a different study that I vaguely remember hearing about a while ago, ...
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Millisecond pulsar timing analysis on fits file

I'm amateur to astronomy and I just want to calculate the spinning period of a pulsar (for example MAXI J0911-655) from lightcurve of it. I found Xamin then I collected data for MAXI J0911-655. Using ...
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156 views

How do I find the signs that planets are in during any given date?

Say for example I wanted to know where the planets were on December 19th, 1664, at 1am; how do I figure that out?
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What is the difference between emission line and recombination line?

When an electron jumps from higher level to lower level a photon is emitted. This is seen as an emission line. But what exactly is a recombination line? I found them similar. Can you please tell me ...
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Position of a star on the HR diagram

Does the position of a star on a HR diagram depend on the magnitude system/color index used? I made a CMD of a particular cluster using HST WFC3/UVIS data, and when I plotted $F275W vs F275W - F606W$...
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What are optical counterparts?

There surprisingly no proper definition of this term available on google. There are many research papers that are based on "finding the optical counterparts". What exactly are optical counterparts ...
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Is there a reason two interstellar objects were found in the solar system in such a short period of time?

ʻOumuamua was discovered on October 19, 2017, and 2I/Borisov was discovered on August 30, 2019. Has something changed about observation techniques or equipment that made it possible to find these ...
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Did nobody in the Astronomy community think 12,000 new satellites in LEO might be a problem?

This answer to Can / should the Starlink satellites be blackened? mentions Space News' SpaceX working on fix for Starlink satellites so they don’t disrupt astronomy where SpaceX chief operating ...
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Relationship between Color Index and Temperature

Is there an exact relationship between color indices and temperature? I have seen some numerical formulas relating B - V color index to temperature, of the form $B - V = a_1 + \frac{a_2}{T} $ . I ...
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Aligning of 7 unidentified objects in the sky, what are they? What did I see? [duplicate]

So this morning (4th December 2019, 0518hrs) I was out turning my horses out in the fields and noticed a strange arrangement of what I perceive to be stars, only I’ve never seen it before and wondered ...
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318 views

How to calculate parallactic angle from a fixed alt-az position?

Say we have an observer at a specified latitude and longitude on Earth who would like to observer a specific fixed alt-az sky position (rather than RA and dec), for example to look at geosynchronous ...
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1answer
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Align multiple fits images without WCS for future aperture photometry analysis

Recently I have got a bunch of raw fits images (2048x2048 pixels) of the same sky region without WCS to process in iraf. However, those images are not well-aligned. There would be around 4~5 pixels' ...

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