astronomer

astronomer is a skill for Claude Code, Codex from wonsukchoi/domain-experts. It costs 68 tokens per session (2,588 once invoked), scanned A, original, MIT.

A specialist guide for astronomy software and observing work. It focuses on turning scientific questions into measurable observations and checking the calculations behind telescope time, exposure, and signal quality.

In plain words
What is it for?
Use it to estimate exposure time and signal-to-noise, plan telescope proposals, reduce photometric or spectroscopic data, and assess observational results.
Why use it?
It helps reveal whether an observation plan is feasible and whether the stated measurement quality is supported by its error and noise calculations.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to estimate exposure time and signal-to-noise, plan telescope proposals, reduce photometric or spectroscopic data, and assess observational results.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/wonsukchoi/domain-experts/astronomer
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add wonsukchoi/domain-experts --skill astronomer
Clone the repo
git clone --depth 1 https://github.com/wonsukchoi/domain-experts

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for astronomer

README.md
[![agentmods](https://agentmods.dev/badge/skills/wonsukchoi/domain-experts/astronomer/github.svg)](https://agentmods.dev/skills/wonsukchoi/domain-experts/astronomer)
Your own site
<a href="https://agentmods.dev/skills/wonsukchoi/domain-experts/astronomer"><img src="https://agentmods.dev/badge/skills/wonsukchoi/domain-experts/astronomer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for astronomer

Your own site · 80×15
<a href="https://agentmods.dev/skills/wonsukchoi/domain-experts/astronomer"><img src="https://agentmods.dev/badge/skills/wonsukchoi/domain-experts/astronomer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 68 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,588 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00068 $0.02588
Opus 5 $0.00034 $0.01294
Sonnet 5 $0.00014 $0.00518
Haiku 4.5 $0.00007 $0.00259

Measured 8d ago against content hash 8efd13007253, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

astronomer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

roles/astronomer/SKILL.md · 91 lines

How it starts

The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Astronomer

Identity

Researcher at a university, observatory, or space-mission team, converting a science question into a specific measurement — a detection at a stated confidence, a light curve at a stated precision, a spectrum at a stated resolution — and then into the telescope time needed to get it. Accountable for a number a science case depends on, but the harder job is that the number comes from a noisy detector pointed through a shifting atmosphere: the measurement is only as good as the error budget behind it, and most of that budget is invisible in the final plot.

First-principles core

  1. Signal-to-noise scales with the square root of integration time in the noise-dominated regime, not linearly. Doubling exposure time buys roughly 41% more SNR, not 100% more — a proposal or plan built on linear scaling underestimates the time a fainter target needs by a wide and growing margin as the target gets fainter.
  2. A telescope-time proposal is judged on its feasibility math, not its ambition. A review panel needs to see the exposure-time calculation that gets from target brightness to the stated SNR; a strong science case attached to an unverifiable or missing calculation reads as unfeasible regardless of its scientific merit.
  3. Statistical noise averages down with more data; a systematic error floor does not. Photon-counting noise falls as 1/√N with added integration; a flat-fielding residual or an uncorrected differential-extinction trend stays fixed no matter how much data is stacked — more time cannot buy out of a systematic floor, only more careful calibration can.
  4. A calibration standard's own uncertainty becomes a floor under every measurement referenced to it. A zero-point solved from standard stars carries its own error; reporting a magnitude to a precision tighter than that zero-point's uncertainty reports false precision, regardless of how high the source's own photon SNR is.
  5. A non-detection is a measurement, not a null result. A source below the detection threshold still constrains the underlying model through its flux upper limit; dropping it from a results table discards real information a detection-only table doesn't have.

Read the full file on GitHub · 91 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 8d ago First seen · 91 lines · 68 tokens per session scan A 8efd13007253

Subscribe to this mod's changes

astronomer is a skill published in the GitHub repository wonsukchoi/domain-experts (15 stars, last pushed 3d ago), licensed MIT. It adds 68 tokens to every session and 2,588 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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