Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

2039-04-15astronomy score per night — click a bar for that night2039-05-14

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-04-15 Fri	—	unknown	—	72.5° 15:35	7.3	48%	121.8°
2039-04-16 Sat	—	unknown	—	72.5° 15:30	7.24	37%	108.5°
2039-04-17 Sun	—	unknown	—	72.5° 15:30	7.19	27%	95.4°
2039-04-18 Mon	—	unknown	—	72.5° 15:25	7.13	19%	82.5°
2039-04-19 Tue	—	unknown	—	72.5° 15:20	7.07	12%	69.9°
2039-04-20 Wed	—	unknown	—	72.5° 15:15	7.01	6%	57.5°
2039-04-21 Thu	—	unknown	—	72.5° 15:10	6.95	2%	45.3°
2039-04-22 Fri	—	unknown	—	72.5° 15:10	6.9	0%	33.4°
2039-04-23 Sat	—	unknown	—	72.5° 15:05	6.84	0%	21.7°
2039-04-24 Sun	—	unknown	—	72.5° 15:00	6.78	2%	10.8°
2039-04-25 Mon	—	unknown	—	72.5° 14:55	6.72	6%	6.8°
2039-04-26 Tue	—	unknown	—	72.5° 14:50	6.66	11%	16.0°
2039-04-27 Wed	—	unknown	—	72.5° 14:50	6.6	17%	27.3°
2039-04-28 Thu	—	unknown	—	72.5° 14:45	6.55	25%	38.9°
2039-04-29 Fri	—	unknown	—	72.5° 14:40	6.49	34%	50.8°
2039-04-30 Sat	—	unknown	—	72.5° 14:35	6.43	43%	63.0°
2039-05-01 Sun	—	unknown	—	72.5° 14:35	6.37	53%	75.4°
2039-05-02 Mon	—	unknown	—	72.5° 14:30	6.31	64%	88.2°
2039-05-03 Tue	—	unknown	—	72.5° 14:25	6.26	74%	101.4°
2039-05-04 Wed	—	unknown	—	72.5° 14:20	6.2	83%	115.1°
2039-05-05 Thu	—	unknown	—	72.5° 14:15	6.14	91%	129.3°
2039-05-06 Fri	—	unknown	—	72.5° 14:15	6.08	96%	143.8°
2039-05-07 Sat	—	unknown	—	72.5° 14:10	6.03	100%	158.4°
2039-05-08 Sun	—	unknown	—	72.5° 14:05	5.97	100%	171.7°
2039-05-09 Mon	—	unknown	—	72.5° 14:00	5.91	97%	168.6°
2039-05-10 Tue	—	unknown	—	72.5° 13:55	5.86	91%	154.6°
2039-05-11 Wed	—	unknown	—	72.5° 13:55	5.8	83%	140.2°
2039-05-12 Thu	—	unknown	—	72.5° 13:50	5.75	74%	125.9°
2039-05-13 Fri	—	unknown	—	72.5° 13:45	5.69	63%	112.1°
2039-05-14 Sat	—	unknown	—	72.5° 13:40	5.64	52%	98.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-04-15&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.