StarForge

Generate beautiful, accurate astronomical star charts in Python.

StarForge is a high-fidelity astronomical visualization engine that transforms real celestial mechanics into beautiful, publication-ready vector star charts.

"It is not a toy sky plotter."

StarForge combines:

• Physically accurate astronomy (Skyfield, real ephemerides, Hipparcos catalog)

• Smart decluttering & perceptual filtering

• A fluent, composable API

• A professional SVG rendering pipeline

• CLI + library parity

All while remaining deterministic, scriptable, and design-grade.

Features

• Simple API - One line to generate a beautiful star chart
• Fluent Interface - Chain methods for easy configuration
• Accurate Astronomy - Uses Skyfield for precise star positions
• Fuzzy Location Search - Type "New York" or "NYC" - it just works
• Multiple Date Formats - Supports "2024-12-25", "25/12/2024", etc.
• Customizable - Colors, sizes, labels, effects, and more
• High Quality SVG - Scalable vector output for any resolution

Usage

StarForge can be used both as a Python library and as a command-line tool. The API is designed to be fluent, composable, and easy to read, while still allowing deep control over astronomical accuracy and visual styling.

---

Installation

pip install py-starforge

Python 3.9+ recommended

---

Quick Start (Recommended)

Generate a star chart in a single line:

from Starforge import StarForge

StarForge("Paris").render("paris_sky.svg")

This generates an accurate SVG star chart of the sky visible from Paris at the current time.

---

Fluent API Usage

StarForge supports a fluent, chainable API for expressive configuration:

from Starforge import StarForge

(
    StarForge("Tokyo")
        .at_date("2024-06-15 22:00")
        .with_fov(60)
        .with_magnitude_limit(5.0)
        .without_labels()
        .with_circular_mask()
        .render("tokyo_sky.svg")
)

---

Setting Location

Using a City Name

StarForge("New York").render("nyc_sky.svg")

City names are resolved using fuzzy matching and population weighting.

Using Coordinates

StarForge("28.61, 77.20").render("delhi_sky.svg")

Using Explicit Coordinates

StarForge("Delhi").at_coordinates(28.61, 77.20).render("delhi_sky.svg")

---

Setting Date & Time

Using a String (Multiple Formats Supported)

chart.at_date("2024-12-25")
chart.at_date("25/12/2024 22:30")
chart.at_date("2024-12-25 22:30")

Using a datetime Object

from datetime import datetime
import pytz

chart.at_datetime(datetime(2024, 12, 25, 22, 30, tzinfo=pytz.utc))

Current Time

chart.now()

---

Field of View (Zoom)

chart.with_fov(90)   # Full hemisphere (default)
chart.with_fov(60)   # Zoomed
chart.with_fov(30)   # Deep zoom near zenith

---

Star Density Control

Limit faint background stars:

chart.with_magnitude_limit(4.5)  # Bright stars only
chart.with_magnitude_limit(6.5)  # Dense sky

---

Labels & Annotations

chart.with_labels(True)
chart.without_labels()

---

Chart Shape & Projection

Circular Mask

chart.with_circular_mask()

Sphere / Globe Effect

chart.with_sphere_effect(True, strength=0.6)

---

Styling & Colors

chart.with_colors(
    background="#050505",
    stars="#ffffff",
    lines="#ffffff",
    labels="#ffcc00",
)

---

Size & Resolution

chart.with_size(1000)        # Square
chart.with_size(1200, 800)   # Rectangular

SVG output is resolution-independent and print-ready.

---

Advanced Styling

Star Sizes

chart.with_star_sizes(
    constellation=14.0,
    background=7.0
)

Constellation Line Style

chart.with_line_style(
    width=1.2,
    opacity=0.8
)

Label Style

chart.with_label_style(
    font_size="12px",
    font_family="Arial",
    opacity=0.9
)

---

Procedural Background Stars

chart.with_procedural_stars(enabled=True, count=300)

Useful for artistic or stylized charts.

---

Custom Star Icons (SVG)

chart.with_custom_icons(
    constellation_star_file="icons/star_main.svg",
    background_star_file="icons/star_bg.svg"
)

---

Rendering & Saving

chart.render("output.svg")
chart.save("output.svg")  # Alias

If the .svg extension is omitted, it is added automatically.

---

Command-Line Interface (CLI)

StarForge includes a first-class CLI for automation and scripting.

Basic Usage

starforge "Paris" paris.svg

With Options

starforge "New York" nyc.svg \
  --date "2024-12-25 22:00" \
  --fov 60 \
  --magnitude 5.0 \
  --no-labels \
  --circular

Quiet Mode

starforge "Tokyo" tokyo.svg --quiet

---

Log Levels

Control console output verbosity:

from starforge import StarForge, Log, LogLevel

Log.set_level(LogLevel.WARNING)  # Only warnings and errors
Log.set_level(LogLevel.SILENT)   # No output

StarForge("Paris").render("quiet.svg")

Legacy API (Still Supported)

from Starforge import create_starmap

create_starmap("Paris", "paris_sky.svg")
create_starmap("28.61, 77.20", "delhi_sky.svg")

---

Typical Workflow

(
    StarForge("London")
        .at_date("2024-10-01 21:00")
        .with_fov(45)
        .with_magnitude_limit(5.5)
        .with_circular_mask()
        .with_colors(background="#000000", stars="#ffffff")
        .render("london_sky.svg")
)

---

StarForge is designed to scale from one-line scripts to production pipelines without changing how you think about the sky.

Configuration Options

Method	Description
.at_date(date)	Set observation date/time
.with_fov(degrees)	Field of view (default: 90)
.with_magnitude_limit(mag)	Star brightness filter (default: 6.0)
.with_labels() / .without_labels()	Toggle constellation labels
.with_circular_mask()	Clip to circular shape
.with_sphere_effect(enabled, strength)	3D globe distortion
.with_size(width, height)	Chart dimensions in pixels
.with_colors(...)	Customize colors
.with_star_sizes(...)	Star icon sizes
.with_line_style(...)	Constellation line style

Examples

See more examples in examples.py & their outputs in outputs

Run specific examples:

python examples.py basic
python examples.py dates
python examples.py colors
python examples.py all

License

MIT License - see LICENSE file.

Author

Developed by Aditya Gaur (@xdityagr)

Links

• GitHub Repository
• PyPI Package
• Report Issues