ddahlen

6 ms·

1.
by ddahlen 16d ago
The writing style has significantly improved, however the token burn rate for tasks I have been working on seems to have skyrocketed. It definitely appears more capable (though I am unclear how much of that is just me liking the English it
2.
by ddahlen 2mo ago
Strictly from an energy conservation argument this doesnt make a whole lot of sense to me. Just some back of the envelope math if they take their current mirror size, make 50k of them and overlap all of the output on the same 3 mile spot (t
3.
by ddahlen 3mo ago
You can put in a public comment on these changes here: https://www.federalregister.gov/documents/2026/05/29/2026-10...
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by ddahlen 3mo ago
I am a researcher studying orbital dynamics of asteroids/comets/dust. I made a very precise visualization tool for the solar system, it shows the motion of all of the known asteroids. When you click on a specific asteroid it will
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by ddahlen 4mo ago
Research grade orbital mechanics, specifically of asteroids/comets. I've been working on it for 4 years now, finally tried using some AI tooling the last few months and ended up vibe coding a fun little visualization. (Desktop Str
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by ddahlen 1y ago
I suggest the appendix of the arxiv paper if you want to see some of the math required for solar system objects beyond simple Newtonian gravity (like Relativity corrections). I wrote that section specifically because I found it a pain in th
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by ddahlen 1y ago
Its an implementation of a pretty standard integrator used by astronomers informally called "RADAU", but it is not exactly the same RADAU you would find elsewhere. Basically it is about as good as you can typically get for multi-s
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by ddahlen 1y ago
Working on orbital dynamics code for my PhD in astronomy, written in rust, it can accurately calculate the positions of all asteroids/comets to within a few meters. Today I am adding a new numerical integration method which should enab
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by ddahlen 1y ago
Here you go, here is its orbit from 1900 to 2100 in the earth's rotating frame, sun is at -1 on the x axis. https://dahlend.github.io/2025_PN7_Orbit_1900-2100.png Its hanging out for a while near us. Shameless plug for
10.
The Asteroid Spin Barrier(dahlend.github.io)
3 points by ddahlen 1y ago|0 comments
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by ddahlen 1y ago
I made a 3D visualization of this a few weeks ago: https://dahlend.github.io/the_belt.html This includes about 1.3 million known asteroids (most of the known ones), so the page is like 45mb. Consider yourself warned. This i
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by ddahlen 1y ago
One good reason to keep the raw data and orientation separate is hardware calibrations. I see some discussion here along the lines of "why not just flip the data before saving it", and one counter-argument is that you should store
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by ddahlen 1y ago
There are quite a few open source projects in astronomy, but in my experience there is a tremendous amount of code that is squirrelled away as it is difficult to reproduce and entrenches peoples positions. I have mixed feelings about this i
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Show HN: precision asteroid orbital dynamics library(github.com)
7 points by ddahlen 1y ago|0 comments
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by ddahlen 1y ago
I am a professional astronomer, and I am running a survey for asteroids. This needs to be controlled from python, as it decides every night which objects to observe. I also heavily use Jupyter for analysis, and with this code I can take ove
16.
by ddahlen 1y ago
https://www.cambridge.org/core/journals/international-astron... Here is a heavily used method in astronomy, this involves a higher order polynomial expansion than RK4. This method has been extended a few times, my
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by ddahlen 1y ago
This is really impressive! I considered buying a big harmonic drive mount for my scope, but the cost is really prohibitive. I have experienced the pain of getting ekos/kstars/indi tools to work well on my personal scope. If you wa
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by ddahlen 1y ago
It is neat to see some of the old work done in the field, this looks like a pretty classic treatment of the topic. It looks like they were using a fourth-order Runge-Kutta integrator, which would likely limit long term integrations accuracy
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by ddahlen 1y ago
Final edits of a paper at the moment, aim to submit next week. Perturbers are easy to add, though a little poorly documented at the moment. Additional physics right now are J2 of jupiter/sun/earth, and GR corrections for the sun a
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by ddahlen 1y ago
I wrote a custom implementation of the Radau integrator, its been heavily modified. I have a lot of additional physics, it supports the non-gravitational models that JPL Horizons defaults to, so diurnal yarkovsky at least. I've been us
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by ddahlen 1y ago
Different goals, kete is meant to be aimed more toward observers and telescope data processing, all asteroids and comets at once on a laptop. Short term analysis (<100 years) and speed are the priority.
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by ddahlen 1y ago
Oort cloud comets are so distant that they are only weakly gravitationally bound to the solar system. When they come in and we see them, they have enough energy to go back out to the extreme distances. Minor nudges from the big planets are
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by ddahlen 1y ago
Eccentricity! You can approximate the orbits of basically everything in the solar system using 2-body mechanics (IE, ignore the planets). If you do this you get orbits which are elliptical (eccentricity <1), parabolic (eccentricity = 1),
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by ddahlen 1y ago
I'm one of those astronomers! I'm working on my PhD in orbital dynamics. A lot of people are requesting discretionary time on telescopes trying to get observations in. The orbit will put us on the other side of the sun when 3I is
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by ddahlen 1y ago
This orbit visualization uses a simple 2 body approximation, so only the sun. This is because unless an object has a VERY close approach to a planet the two body approximation is more then enough for this style of visualization. I did a ful
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by ddahlen 1y ago
The closest it will come is Mars, but when I say close these are quite literally astronomical distances, about 0.2 au from Mars. This is about 75x further than the moon is from the Earth. If it is an inactive rock, then we will not see it a
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by ddahlen 1y ago
I would recommend staying on Earth...
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by ddahlen 1y ago
It is also a factor of where our surveys look on the sky. A lot of asteroid surveys have biases to look at the plane of our solar system (since this is where a lot of asteroids are). It is probably random chance, however there may be some b
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by ddahlen 1y ago
This is an announcement from the Minor Planet Center (MPC). They are the official international clearing house for observations of solar system objects. The top indicates that the object has two names (this is common): 3I/ATLAS = C&#x
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by ddahlen 1y ago
It is inside jupiter's orbit now, it will come inside Mars for a time. It is almost on the plane of the solar system, not very inclined. I linked an orbit viewer above if you want to look.

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