fourmost-spectrograph-animation

name	fourmost-spectrograph-animation
title	4MOST Spectrograph Animation (Manim)
description	Generates a 60-90s educational animation of the 4MOST spectrograph on the VISTA 4-m telescope using Manim Community Edition. Follows a schematic-first workflow: static matplotlib plot for review, then Manim animation. Includes tilting-spine fibres, three spectrographs (HRS/LRS), optical train, and science output.
category	data-science
triggers	["4most animation","4most manim","4most spectrograph animation"]

Workflow

Step 1 — Schematic first. Create a static matplotlib multi-panel figure so the user can review and approve the visual design before committing to animation time.

Step 2 — Manim animation. Once the schematic is approved, generate the full Manim script and render.

Step 1 — Schematic (matplotlib)

Colours

BG       = "#0D1117"   # dark background
BLUE     = "#58C4DD"
GREEN    = "#83C167"
YELLOW   = "#FFFF00"
ORANGE   = "#F5A623"
WHITE    = "#E6EDF3"
GRAY     = "#8B949E"

Panels (6 total)

A. VISTA dome + 4MOST instrument box at Paranal B. Wide field cone (≈2.5°) with stars/galaxies C. Curved focal surface + tilting-spine fibres (2436 fibres) D. Fibres → 3 spectrographs: HRS (812 fibres) + LRS-1/LRS-2 (1624 fibres total) E. LRS optical train: slit → collimator → dichroics → VPH gratings → CCDs F. Spectral grid → science: element lines, velocity shifts, Milky Way spiral

Rendering

python3 /home/hermes/4most_schematic.py
# Output: /home/hermes/4most_schematic.png

## When to Use
Generates a 60-90s educational animation of the 4MOST spectrograph on the VISTA 4-m telescope using Manim Community Edition. Follows a schematic-first workflow: static matplotlib plot for review, then Manim animation. Includes tilting-spine fibres, three spectrographs (HRS/LRS), optical train, and science output.

## Overview
This skill contains a reusable operational workflow. Follow the existing task-specific steps and examples in the sections below.

Step 2 — Manim Animation

Technical Facts to Respect

• Mounted on VISTA 4-m telescope at ESO Paranal
• Field of view: ≈2.5° diameter at Cassegrain focus
• 2436 science fibres in tilting-spine positioner on curved focal surface
• 3 spectrographs via fibre bundles: HRS (812 fibres) + 2× LRS (1624 total)
• Each spectrograph: 3 wavelength channels (blue/green/red) split by dichroics, VPH gratings, large CCDs

Colour Palette (dark BG style)

BG     = "#0D1117"
BLUE   = "#58C4DD"
GREEN  = "#83C167"
YELLOW = "#FFFF00"
ORANGE = "#F5A623"
WHITE  = "#E6EDF3"
GRAY   = "#8B949E"
REDB   = "#FF6B6B"

6 Visual Sequences

1. VISTA + 4MOST — dome, slit glow, instrument box, title overlay
2. Wide field — cone lines from telescope to sky, random stars/galaxies
3. Tilting-spine fibres — curved Arc for focal surface, 16 fibre tip dots + spine lines, one spine tilting to a star
4. Three spectrographs — focal plane bar → 3 cables → HRS / LRS-1 / LRS-2 boxes
5. LRS optical train — slit dots → collimator circle → dichroics → VPH gratings → CCDs → rainbow dispersion fans
6. Science output — spectrum grid → element/velocity labels → final title

Rendering

# Low-quality preview first
cd /home/hermes
manim -ql --renderer=cairo -r 1280,720 4most_animation.py FourMOST_Full

# Concatenate partial MP4 files
OUT_DIR=$(find /home/hermes/media/videos/4most_animation -name "partial_movie_files" -type d)
SCENE="FourMOST_Full"
PARTIAL=$(find "$OUT_DIR" -name "*.mp4" | grep "$SCENE" | sort)
echo "$PARTIAL" | awk '{print "file '"'"'" $0 "'"'"'"}' > concat.txt
ffmpeg -y -f concat -safe 0 -i concat.txt -c copy /home/hermes/4most_animation_final.mp4

# High-quality final render (run in background)
manim -qh --renderer=cairo -r 1920,1080 4most_animation.py FourMOST_Full

Pitfalls & Gotchas

• No python binary — always use python3
• next_section() calls require no setup but produce no visible effect unless using a notebook renderer
• FadeOut + self.remove — when fading out a VGroup that includes dynamically added individual mobjects (e.g. stars from make_stars()), fade out the VGroup first, then call self.remove() separately on individual mobjects
• Line not Arrow — use Line for static rays to avoid VMobject.scale() errors
• Hex colour parsing — Manim CE handles hex fine; don't mix with named constants carelessly
• Background renders — use terminal(background=true, notify_on_complete=true) for >60s renders
• Partial files — Manim splits long scenes; always concatenate with ffmpeg after render
• Old partial files — check find ... -newer script.py to find recently generated files

Verification

Check final output:

ls -la /home/hermes/4most_animation_final.mp4
ffprobe /home/hermes/4most_animation_final.mp4 2>&1 | head -10