Skip to main content

Questions tagged [observational-astronomy]

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

Filter by
Sorted by
Tagged with
0 votes
1 answer
30 views

Using SExtractor for JWST data

I am new to this tool for catalogue creation(SExtractor). I want to know about how to set parameters for the extraction for JWST data. The parameter file looks like this. ...
Walker's user avatar
  • 61
1 vote
1 answer
46 views

Mathematical modeling of the influence of components of the interstellar medium on the distortion of the wavefront of the observed object

Associated with: Flowchart of the pipeline of key processes for modeling wavefront distortion of astronomical objects: ground-based observation case Let's imagine for a moment that we are outside the ...
ayr's user avatar
  • 825
1 vote
1 answer
34 views

Flowchart of the pipeline of key processes for modeling wavefront distortion of astronomical objects: ground-based observation case

Associated with: Mathematical modeling of the influence of components of the interstellar medium on the distortion of the wavefront of the observed object Being inspired by this article, as well as ...
ayr's user avatar
  • 825
1 vote
0 answers
56 views

How hard or soft is the Hubble's "science floor" due to atmospheric torque? Do some kinds of observations have lower floors than others?

After 04:58 in Scott Manley's How Failed Gyros Are Making Hubble's Life Harder: And while the telescope is floating in space, it is still subject to small forces which can adjust its orientation. ...
uhoh's user avatar
  • 30.7k
1 vote
1 answer
79 views

What is the "handful of observations of close fast moving objects that (Hubble) can't actually track anymore" due to the new one-gyro operation?

After 13:49 in Scott Manley's How Failed Gyros Are Making Hubble's Life Harder: And so with all these systems working together, the telescope can still point at the target and still do top quality ...
uhoh's user avatar
  • 30.7k
2 votes
1 answer
83 views

What are the reference signal(s) for a closed-loop space-based adaptive optical system?

Closed-loop control systems in general have the following form: Here the controller seeks to eliminate or minimize the difference between a given signal (this can be either a constant signal of the ...
ayr's user avatar
  • 825
5 votes
2 answers
567 views

Difference in field of view between JWST and Euclid

I was watching this video about the Euclid telescope. At the 8 minute mark he compares the field of vide of Euclid with that of the JWST, showing that the Euclid field of view is much larger. While I ...
Erontado's user avatar
  • 151
2 votes
0 answers
20 views

How to convert .exp files from NRAO VLA Archive to .fits format

I recently downloaded some observational data files from the NRAO VLA Archive, and they have the extension .exp. These are old observations. I need to convert these files to .fits format for further ...
Eduardo Quiroz's user avatar
2 votes
3 answers
142 views

Parameters erroneously measured to be negative

I am interested in physical quantities which are strictly non-negative, but which, due to errors, may realistically be estimated as negative. The only examples I can think of are interstellar ...
J. Webb's user avatar
  • 53
13 votes
4 answers
2k views

Vera C. Rubin's LSST's ginormous camera's shutter; why does it open/close 1000 times a night & is this typical for large-format survey telescopes?

CNET's April 23, 2024 World's Largest Camera, the 3.2-Gigapixel LSST, Is Complete says after about 02:19 That shutter is actually so big it had to be broken down into two pieces just to fit inside ...
uhoh's user avatar
  • 30.7k
1 vote
1 answer
106 views

Does the lower value of the Hubble Constant predicted by the Planck Satellite and now confirmed by Wendy Freedman invalidate the idea of dark energy?

Is the dark energy part of the Lambda-CDM model (the 'lambda') still necessary if the value of the Hubble 'constant' is lower than that predicted by Adam Reiss and collaborators when they examined ...
Kurt Hikes's user avatar
  • 5,177
1 vote
0 answers
71 views

Declinations from stars apparent motion w/o plate solving

I am trying to program the calculation of the declination of the stars, based on their apparent movement through a series of astrophotographs, purely algebraically, without using a solver based on the ...
Danko Dnevic's user avatar
3 votes
1 answer
60 views

Most established length of Gleissberg Cycle

What is the most commonly used length for the Gleissberg Cycle of sunspots? I have reviewed academic literature on the subject and the lengths used are all over the place. Specifically, anywhere in ...
Daniel J Rice's user avatar
1 vote
0 answers
40 views

Tiling the sky with astropy-healpix

I have a bunch of files containing sources with galactic l and b values. What I want is to redistribute the sources such that each new file contain sources that fall within 15 degrees of a central l,b ...
Debajyoti Sengupta's user avatar
8 votes
1 answer
198 views

Basics of Tracklet-less Heliocentric Orbit Recovery (THOR) - simple breakdown of how it works?

The New York Times's April 30, 2024 Killer Asteroid Hunters Spot 27,500 Overlooked Space Rocks begins: With the help of Google Cloud, scientists churned through hundreds of thousands of images of the ...
uhoh's user avatar
  • 30.7k
2 votes
0 answers
99 views

What would the Big Crunch theoretically look/feel like?

In the Big Crunch theory, the expansion of the universe reverses, resulting in all matter contracting into a single point. Imagine you are alive at the time of this event. What would the sky look like?...
value1's user avatar
  • 29
2 votes
0 answers
55 views

How did Herschel determine the diameter of Mars?

The book The Planet Mars: A History of Observation and Discovery by William Sheehan states that Herschel calculated the diameter of Mars to be 0.55 times that of the Earth, and he found its figure to ...
usernumber's user avatar
  • 17.6k
0 votes
0 answers
60 views

Looking straight through the Milky Way Galaxy with the Gedanken Space Telescope from radio to 100 keV, what would the opacity vs wavelength look like?

Imagine that the "Large Gedanken Cryogenic Space Telescope" has been commissioned and aligned and is ready for its first test. It is equipped with a closed-cycle helium refrigerator to ...
uhoh's user avatar
  • 30.7k
2 votes
1 answer
65 views

Which of the blocked radiation windows will (mostly) open if one where to observe from the surface of Mars, instead of the Earth?

Earth’s atmosphere is composed of about 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.1 percent other gases. Trace amounts of carbon dioxide, methane, water vapor, and neon are some ...
some_math_guy's user avatar
1 vote
0 answers
51 views

Has anyone attributed a specific Baily's bead to a specific feature on the Moon? If so, when was this first done?

From Wikipedia's Baily's beads: Lunar topography has considerable relief because of the presence of mountains, craters, valleys and other topographical features. The irregularities of the lunar limb ...
uhoh's user avatar
  • 30.7k
5 votes
1 answer
206 views

Relative inclination with respect to line of sight

I'm encountering some difficulty understanding the concept of line of sight inclination. Typically, we assume that the observer is positioned perpendicular to the system being observed. Consequently, ...
RKerr's user avatar
  • 195
4 votes
1 answer
537 views

Can an astronomer fully work remotely? [closed]

My question today is addressed to those astronomers who have quite a lot of experience working remotely. In general terms, the answer to the question includes the following elements: the range of ...
ayr's user avatar
  • 825
0 votes
0 answers
72 views

How can I convert luminosity from [erg/s/Hz] to [erg/s]

I have the dust-corrected luminosity in the Ks band in the unit erg/s/Hz. I want to convert it to erg/s. I would like to know which method is correct: $L[erg/s]=L[erg/s/Hz]\times(C/\lambda)$ $L[erg/s]...
Fatemeh Abedini's user avatar
2 votes
2 answers
122 views

What exactly was "The curse of Sisyphus" and why did it take so long to find out about the radar detection of its companion?

This answer to First satellite of an asteroid (or double asteroid) ever imaged by delay-Doppler radar? mentions that Wikipedia's 1866 Sisyphus; Binary system says: In 1985, this object was detected ...
uhoh's user avatar
  • 30.7k
3 votes
1 answer
491 views

Measure the radius of the earth using the sun?

Can someone tell me why this would or would not work? I have a sun spotter device that projects an image of the sun onto a piece of paper using a lens and some mirrors. When you use the device it’s ...
James Thiamin's user avatar
3 votes
0 answers
33 views

What are the technologies needed to make deep space LIDAR competitive with RADAR? Any plans for tests, prototypes or "pathfinder" systems?

ProfRob's answer to Would it be practical to map out the Kuiper Belt and Oort Cloud via Radar? gives us a "sobriety check" on the idea. Citing an example of a 1 million watt transmitter at ...
uhoh's user avatar
  • 30.7k
4 votes
1 answer
119 views

Extend CDF to physical range

Consider the following observations regarding the eccentricities of stellar binaries (just an example): $$e = [0.3, 0.45, 0.2, 0.52, 0.64, 0.34]$$ We can calculate the cumulative distribution function ...
RKerr's user avatar
  • 195
0 votes
0 answers
67 views

Tolerances given for Galactic Directions in answer to 'How fast are we moving relative to the CMB?'

Question: Tolerances given for Galactic Directions, in answer to 'How fast are we moving relative to the CMB?' Where: $$ℓ = 264.021º ± 0.011º$$ $$𝑏 = 48.253º ± 0.005º$$ I can find these values on ...
DaveAt168's user avatar
2 votes
0 answers
65 views

Who named "the 37 cluster" or at least made that name widely known via writing?

The March 29, 2024 Veritasium video Why is this number everywhere? is about an apparent prevalence of the number 37 (for at least some people, including ) and in a montage of instances of 37 it shows &...
uhoh's user avatar
  • 30.7k
0 votes
0 answers
94 views

Largest Optical Telescope NOT at Higher Elevation

It's trivial to find the list of largest optical telescopes by aperture size. What I'm interested in is the largest optical telescope in the world, regardless of ownership or origin (amateur or ...
Chris's user avatar
  • 1
3 votes
1 answer
522 views

Automated (and hopefully free) systems I can subscribe to sending email or SMS text message when the T Coronae Borealis Nova becomes visible?

My earlier question about predicted potentially observable events Has a gravitational microlensing event ever been predicted? If so, has it been observed? is limited to microlensing. Now I have just ...
uhoh's user avatar
  • 30.7k
2 votes
0 answers
36 views

Stacking of frames drizzled using the AURA drizzle implementation hosted on github/spacetelescope (NOT PixInsight drizzle integration)

Note: this question is not about PixInsight's drizzle integration module, it's specifically about the mentioned drizzle implementation. Answers describing PI functionality are automatically off topic. ...
Adrian K-B.'s user avatar
0 votes
0 answers
69 views

Why are paths of solar eclipses symmetrical around a January 2015 axis?

My cousin, James Andrews, observed that the paths of eclipses before and after Jan 2015 form a symmetry. Here is a visual description I know there's a logical explanation, but it's been ascribed a ...
effbiae's user avatar
  • 101
5 votes
1 answer
796 views

Is there any way to detect the three-dimensional distribution of baryonic gas in our Universe?

As the title suggests, can the current observational techniques detect the 3D large-scale distribution of the baryonic gas, rather than just the gas within groups or clusters?
Wang Yun's user avatar
  • 431
0 votes
0 answers
33 views

Horizons SPK file with a different coordinate center than I asked for

I am using the JPL horizons app to generate an SPK file for Chiron (ID: 20002060) with respect to the solar system barycenter (ID: 0). However, the generated SPK file says the center is with respect ...
Hunter's user avatar
  • 321
5 votes
1 answer
440 views

What will it take to start measuring the rotation rate and direction of exoplanets? Which instrument(s) current or future are most likely to do it?

@ProfRob's answer to Is it coincidence that the earth's rotation and revolution are in the same direction? explains several important aspects of models for planetary formation, angular momentum and ...
uhoh's user avatar
  • 30.7k
7 votes
1 answer
201 views

Attempting to plot solar terminator using Python and Skyfield library

Problem I would like to plot the small circle defining the visible portion of Earth for an observer at position $P$ away from the Earth, on a 2D map. In the case of the Sun, this would be the solar ...
Hunter's user avatar
  • 321
1 vote
2 answers
149 views

Calculate geographical location (latitude, longitude) from horizontal and equatorial coordinates, date and UT

Lets say I found myself in the middle of nowhere with small computer with some sort of offline astrometry engine (like locally installed astrometry.net). I have some sort of mount that precisely tells ...
jlipinski's user avatar
  • 297
1 vote
1 answer
73 views

For detection of distant galaxies by gravitational lensing-induced magnification, roughly what are the distance ratios from the lensing systems?

Discussion in comments under the question Does seeing a gravitationally lensed/magnified galaxy imply that they could also see us as well? have got me wondering about the geometry behind detection of ...
uhoh's user avatar
  • 30.7k
0 votes
1 answer
83 views

how much does 1 second of error impact sidereal tracking?

Usually observatories have time servers on site for reasonable time keeping. If I have 1 second of time error, how will this impact sidereal tracking? By how much?
Adrian's user avatar
  • 116
21 votes
2 answers
3k views

Does seeing a gravitationally lensed/magnified galaxy imply that they could also see us as well?

Does an observer in that galaxy see our galaxy magnified as well?
2080's user avatar
  • 1,890
6 votes
1 answer
261 views

First photographic image taken with telescopes to produce astronomically useful results? What telescope was used?

comments on the question and answer(s) to What are the technological advancements that made it possible for modern large telescopes to work with alt-az mounts instead of equatorial mounts? have made ...
uhoh's user avatar
  • 30.7k
-2 votes
1 answer
163 views

Why is v lowercase and D uppercase in $v=H_0D$?

Why is v almost always written in lowercase and D in uppercase in $v=H_0D$? OK, v is in lowercase, as usual, but then why is D in uppercase? What's so different/special about it? In my physics school ...
Curious Cat's user avatar
0 votes
1 answer
91 views

Does a cosmological redshift occur within our local group, of galaxies?

I know that it is not supposed to be expanding but space is space and it is expanding everywhere else outside it so why not inside it too, and gravity just holds everything back. I suppose if it is, ...
Curious Cat's user avatar
1 vote
2 answers
1k views

How can Hubble's original data show that the universe is expanding?

The diagram from Hubble's original data only goes from 0 to 2 Mpc (see here), and yet our Local Group is not supposed to be expanding and it is 1.5 Mpc in radius. How can the data show that the ...
Curious Cat's user avatar
0 votes
0 answers
86 views

What is the name of this eclipse cycle (if there is one)?

Today I navigated to Wikipedia's "Eclipse Cycle" page and found that they had updated their table of eclipse cycles with many more named cycles. However, one particular cycle that I had ...
user22542's user avatar
  • 240
5 votes
0 answers
88 views

Is there a noob-friendly website/app for tracking a astronomical body's apparent movement over time?

As I walk home along my road most nights in winter, I see the Moon and one-or-more planets. Unsurprisingly, over the last 2 months, if it's been the same planet and it (and the Moon) has been in ...
Brondahl's user avatar
  • 338
13 votes
2 answers
4k views

Was this video shot with a ground based hobby astronomer telescope?

I stumbled across this video capturing the rings of Saturn and wanted an expert opinion. This video of Saturn looks so good that I was wondering if it was really shot by a hobby astronomer's telescope ...
Substantialist_Jules's user avatar
9 votes
1 answer
1k views

What is the solar diameter?

What is the solar diameter in SI units? Google tells me this is 1.3927 Gm. How accurate is that figure? I am looking for estimates with referenced data and calculations, and the uncertainties: due to ...
David's user avatar
  • 337
6 votes
1 answer
451 views

What were the specifics of the photos taken by Sir Arthur Eddington during the Eddington expedition that supported Einstein's Theory

I know that Sir Arthur Eddington went to South American to photograph stars around an eclipse to see if they seemed to change position when the light past by the Sun relative to when the light didn't ...
Elliott Cooper's user avatar

1
2 3 4 5
29