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Astrophysics · Cosmology · Olympiad

Understand the universe.
From first principles.

Rigorous, beautifully explained notes and problem sets for curious minds — from your first orbit to the edge of the observable universe.

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Written by olympiad alumni and Astro Olympiad Campers
Built for deep understanding

500+

pages of rigorous
notes & problems

02

languages.
One shared sky.

∞

questions worth
asking next

Every derivation has a reason.
Every problem has a path.

Explore the library

Start anywhere.
Go everywhere.

Celestial mechanics

From Keplerian motion to perturbation theory.

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Observational astronomy

Read the sky through photons, spectra, and surveys.

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Stellar astronomy

The physics of stars, from birth to remnants.

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Galactic astronomy

Structure, dynamics, and the cosmic web.

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Cosmology notes

The origin, evolution, and ultimate fate of the universe.

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Why DotXiv

Less memorising.
More seeing.

01

Bilingual by design

Learn in English or Bangla without losing the nuance of the idea.

02

Derivations, not declarations

We show the path between the question and the equation.

03

Olympiad tested

Problems that reward intuition, persistence, and a little beautiful stubbornness.

04

Free & open access

Knowledge should move freely. So should a curious mind.

✦

A place to ask better questions

The best discoveries
are shared.

Join students, educators, and fellow sky-watchers in the DotXiv community.

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The people behind DotXiv

Contributors

Built by curious people who want astronomy learning to be open, rigorous, and welcoming. This list will grow with DotXiv.

Mohammad Marshad Bin Khaled at an event

Contributor 01

Founder & contributor

Mohammad Marshad Bin Khaled

Astrophotographer, Olympiad Competitor, and Founder of The Dot and DotXiv

Mohammad Marshad Bin Khaled is a Bangladeshi astronomy enthusiast, olympiad competitor, and founder of The Dot, an initiative promoting accessible astronomy education. He received an IAAC International Bronze Honour Award (Top 10% worldwide), ranked 67th in the Online Physics Olympiad 2026, and placed 8th in the IOAA Junior Team Selection Test. Through DotXiv, he aims to make astronomy olympiad preparation more accessible through quality learning resources and challenging practice problems for aspiring young astronomers.

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