fourmost-spectrograph-schematic

name	fourmost-spectrograph-schematic
title	4MOST Spectrograph Schematic
description	Generate a static schematic illustration of the 4MOST spectrograph system as a precursor to a full Manim animation.
author	Hermi (based on user prompt)
version	0.1

Overview

This skill provides a step‑by‑step guide to create a static schematic of the 4MOST spectrograph using Matplotlib (or any preferred plotting library). The schematic includes:

1. VISTA telescope with 4MOST mount.
2. Wide‑field cone (≈2.5°).
3. Tilting‑spine fibre positioner on a curved focal surface.
4. Fibre bundles to three spectrograph boxes (HRS, LRS1, LRS2).
5. Optical train of a low‑resolution spectrograph (slit, collimator, dichroics, VPH gratings, CCDs).
6. Final science view (grid of spectra → Milky Way outline).

Prerequisites

• Python 3.9+
• matplotlib (pip install matplotlib)
• Optional: numpy (usually installed with matplotlib)

Step‑by‑step code

import matplotlib.pyplot as plt
import numpy as np

# ---------------------------------------------------------------------

## When to Use
Generate a static schematic illustration of the 4MOST spectrograph system as a precursor to a full Manim animation.

## Pitfalls
- Do not hardcode credentials, tokens, or personal secrets.
- Verify external service URLs, paths, and permissions before making changes.
- Keep generated outputs reproducible and record input assumptions.

## Verification
- Confirm required inputs and credentials are available.
- Run the smallest safe command or example before scaling up.
- Check produced files, API responses, or plots before reporting success.

# 1. Figure setup (dark background, user colour palette)
# ---------------------------------------------------------------------
fig, ax = plt.subplots(figsize=(12, 7), facecolor="#0D1117")
ax.set_facecolor("#0D1117")

# User colour palette
BLUE = "#58C4DD"
GREEN = "#83C167"
YELLOW = "#FFFF00"
WHITE = "white"

# ---------------------------------------------------------------------
# 2. VISTA + 4MOST (simple dome)
# ---------------------------------------------------------------------
theta = np.linspace(np.pi, 2 * np.pi, 200)
ax.plot(np.cos(theta), np.sin(theta) + 1, color=BLUE, lw=2)
ax.text(0, 2.2, "VISTA 4‑m telescope with 4MOST", color=WHITE, ha="center")

# ---------------------------------------------------------------------
# 3. Wide‑field cone (≈2.5°)
# ---------------------------------------------------------------------
# Scale factor chosen for visual appeal – not a real angular size.
cone_radius = np.tan(np.deg2rad(2.5 / 2)) * 5
ax.add_patch(plt.Circle((0, 0), cone_radius, edgecolor=GREEN, facecolor="none", lw=1, ls='--'))
ax.text(0, -cone_radius - 0.3, "Wide field ≈ 2.5° – thousands of targets", color=WHITE, ha="center")

# ---------------------------------------------------------------------
# 4. Fibre positioner (top‑down view of curved focal surface)
# ---------------------------------------------------------------------
phi = np.linspace(-np.pi / 3, np.pi / 3, 100)
R = 4
x_f = R * np.cos(phi)
y_f = R * np.sin(phi) - 2
ax.plot(x_f, y_f, color=YELLOW, lw=1)
# Hexagonal grid of fibre modules (small circles)
for i in range(-5, 6):
    for j in range(-3, 4):
        ax.plot(x_f[0] + i * 0.3, y_f[0] + j * 0.26, 'o', color=BLUE, markersize=2)
ax.text(0, -2.5, "2436 tilting‑spine fibres", color=WHITE, ha="center")

# ---------------------------------------------------------------------
# 5. Fibres to spectrograph boxes (three cables)
# ---------------------------------------------------------------------
for idx, x_off in enumerate([-2, 0, 2]):
    ax.plot([x_f[-1], x_f[-1] + x_off], [y_f[-1], -4], lw=4, color=GREEN)
    ax.text(x_f[-1] + x_off, -4.5, ["HRS", "LRS1", "LRS2"][idx], color=WHITE, ha="center")

# ---------------------------------------------------------------------
# 6. Low‑resolution spectrograph optical train (simplified)
# ---------------------------------------------------------------------
sp = -2  # x‑position of the spectrograph box
# Slit
ax.add_patch(plt.Rectangle((sp - 0.4, -4.2), 0.8, 0.3, edgecolor=BLUE, facecolor="none", lw=1))
# Collimator (simple line)
ax.plot([sp, sp], [-4.2, -3.8], color=WHITE, lw=1)
# Dichroics – three coloured lines
colors = [BLUE, GREEN, YELLOW]
labels = ["Blue", "Green", "Red"]
for i, c in enumerate(colors):
    y = -3.8 + i * 0.1
    ax.plot([sp, sp + 0.8], [y, y], color=c, lw=1)
    ax.text(sp + 0.9, y, labels[i], color=c, va='center')
# CCDs – small black rectangles
for i in range(3):
    y = -3.85 + i * 0.1
    ax.add_patch(plt.Rectangle((sp + 0.85, y), 0.15, 0.08, facecolor="black"))

# ---------------------------------------------------------------------
# 7. Science view – grid of tiny spectra leading to a Milky Way outline
# ---------------------------------------------------------------------
for i in range(10):
    for j in range(5):
        x0, y0 = -5 + i * 0.5, -7 + j * 0.3
        ax.plot([x0, x0 + 0.3], [y0, y0 + 0.05], color="#AAAAAA", lw=0.5)
ax.text(0, -8, "Spectra → Milky Way map", color=WHITE, ha="center")

# ---------------------------------------------------------------------
# 8. Final touches
# ---------------------------------------------------------------------
ax.set_xlim(-6, 6)
ax.set_ylim(-9, 3)
ax.axis('off')
plt.show()

Tips & Pitfalls

• Colour palette – keep the dark background (#0D1117) and the three accent colours from the user profile (#58C4DD, #83C167, #FFFF00).
• Scale – the schematic is intentionally abstract; the exact angular size of the cone is not critical, only that it visually conveys a wide field.
• Readability – keep text labels short and centred; avoid overlapping with other graphic elements.
• Extensibility – each numbered block corresponds to a future Manim Scene. When moving to animation, you can reuse the same coordinates and colour constants.

Next Steps

1. Run the script and inspect the generated figure.
2. Share the image with the user for feedback.
3. Once approved, translate each block into a Manim Scene (or a single MovingCameraScene) following the same geometry and colour scheme, as described in the original prompt.

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