Moondance

Settings

Observation Location Search for any city or address

Latitude Degrees (-90 to +90)

Longitude Degrees (-180 to +180)

Elevation Meters above sea level

Timezone e.g., America/New_York

Target Object Search for any deep sky object

Start Date Analysis will cover 30 days from this date

Observation Time Local time (typically evening)

ℹ️ Angular separation is 3D celestial sphere distance, not just altitude difference

Enter your observation details above and click "Calculate" to see the chart.

Time Between the Thirties

Imaging Recommendations

Run a calculation to see optimal imaging dates based on moon separation and phase.

Understanding the Chart

🌕 Moon Altitude

Shows how high the moon is above the horizon at your observation time. Negative values mean the moon is below the horizon.

🎯 Target Altitude

Shows how high your target object is above the horizon. Higher altitudes provide better imaging conditions.

📐 Angular Separation

ℹ️ Important: This measures the true 3D angle between moon and target on the celestial sphere, accounting for both altitude and compass direction (azimuth).

Not just altitude difference! A target due east and moon due west can have 130°+ separation even with similar altitudes. This is the correct astronomical measure.

≥90° (green) = Ideal imaging
60-90° (yellow) = Acceptable
<60° or target below horizon (red) = Poor/impossible

💡 Best Practices

For astrophotography, look for dates with:
• Angular separation ≥90° (solid green line)
• Moon phase <20% (new moon period)
• Target altitude >30° (better atmospheric conditions)