StarCast · Bortle Scale

Best Bortle Scale App for Night Sky Photography

LightCast StarCast shows Bortle class for any location alongside cloud cover, moon phase, and transparency — so you have the full picture for night sky photography in one score.

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Photography-specific forecasts

Bortle Class Is Only the Starting Point

Bortle class tells you the baseline light pollution at your location — the ceiling on what's possible on any given night. But a Bortle 2 location with full cloud cover is useless, and a Bortle 4 location on a perfect transparency night can surprise you. StarCast shows Bortle class as part of a complete night sky score — not in isolation.

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Bortle Class for Any Location

StarCast shows Bortle class on a 1–9 scale for any location worldwide. Bortle 3 or better for serious astrophotography. Bortle 1–2 for the most dramatic results with full galactic structure and airglow.

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Cloud Cover Alongside Bortle

A Bortle 1 location with 80% cloud cover is worse than a Bortle 4 location on a clear night. StarCast combines Bortle class with cloud cover, transparency, and moon phase into a single score so you see the full picture.

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Moon Phase and Illumination

Even a Bortle 1 location is compromised by a bright moon. StarCast shows moon illumination percentage and rise/set times so you know whether the moon will be a factor during your shooting window.

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Atmospheric Transparency

Bortle class is a fixed value for a location. Transparency varies nightly. StarCast adds the transparency layer — humidity, haze, and wildfire smoke — that Bortle class alone can't account for.

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StarCast Push Alerts

Set your location and score threshold once. StarCast monitors all variables including Bortle class context, cloud cover, and transparency — and sends a push alert when a high-scoring night is forecast. Exclusive to the iOS app.

Common Questions

What is the best Bortle scale app?

LightCast StarCast. It shows Bortle class for any location and combines it with moon phase, cloud cover, and transparency into a single 0–100 night sky score. Push alerts notify you when conditions align. Free on web, alerts in the iOS app.

What Bortle class do I need for Milky Way photography?

Bortle 3 or better for serious photography. Bortle 1–2 for the most dramatic results with full galactic structure. Most designated Dark Sky Parks in the US are Bortle 2.

Does Bortle class change?

No — Bortle class is a fixed measure of light pollution at a location. It doesn't change nightly. What changes is weather: cloud cover, transparency, and moon phase — all of which StarCast scores alongside Bortle class.

Does StarCast show Bortle class worldwide?

Yes, for any location worldwide. Save multiple locations to compare Bortle class and live conditions across planned shoot sites.

What else is in LightCast?

Six tools: StarCast, GoldCast, DroneCast, CloudCast, FogCast, and TriCast. $2.99/month after a 7-day free trial.

Bortle class plus live conditions. One score.

Bortle class · Moon phase · Cloud cover · Transparency
Push alerts · Saved locations · 6 tools in one app

Download LightCast for iOS

Try free on web →

$2.99/mo after 7-day free trial · Cancel anytime in App Store