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.

Best nights for Seven Sisters: 04-11 (1), 04-12 (1), 04-13 (1) — by astronomy; check the weather when the night is within four days.

2040-04-11astronomy score per night — click a bar for that night2040-05-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-04-11 Wed	1	—	unknown	—	72.5° 15:50	7.49	0%	33.7°
2040-04-12 Thu	1	—	unknown	—	72.5° 15:45	7.43	2%	20.9°
2040-04-13 Fri	1	—	unknown	—	72.5° 15:40	7.37	6%	9.0°
2040-04-14 Sat	0	—	unknown	—	72.5° 15:35	7.32	11%	6.4°
2040-04-15 Sun	0	—	unknown	—	72.5° 15:35	7.26	18%	17.4°
2040-04-16 Mon	0	—	unknown	—	72.5° 15:30	7.2	26%	29.1°
2040-04-17 Tue	0	—	unknown	—	72.5° 15:25	7.14	35%	40.9°
2040-04-18 Wed	0	—	unknown	—	72.5° 15:20	7.08	44%	52.6°
2040-04-19 Thu	0	—	unknown	—	72.5° 15:15	7.03	54%	64.5°
2040-04-20 Fri	0	—	unknown	—	72.5° 15:15	6.97	63%	76.4°
2040-04-21 Sat	0	—	unknown	—	72.5° 15:10	6.91	72%	88.6°
2040-04-22 Sun	0	—	unknown	—	72.5° 15:05	6.85	81%	101.1°
2040-04-23 Mon	0	—	unknown	—	72.5° 15:00	6.79	88%	113.8°
2040-04-24 Tue	0	—	unknown	—	72.5° 14:55	6.74	94%	127.0°
2040-04-25 Wed	0	—	unknown	—	72.5° 14:55	6.68	98%	140.5°
2040-04-26 Thu	0	—	unknown	—	72.5° 14:50	6.62	100%	154.3°
2040-04-27 Fri	0	—	unknown	—	72.5° 14:45	6.56	99%	168.0°
2040-04-28 Sat	0	—	unknown	—	72.5° 14:40	6.5	96%	174.4°
2040-04-29 Sun	0	—	unknown	—	72.5° 14:40	6.44	90%	161.6°
2040-04-30 Mon	0	—	unknown	—	72.5° 14:35	6.39	81%	147.4°
2040-05-01 Tue	0	—	unknown	—	72.5° 14:30	6.33	71%	133.0°
2040-05-02 Wed	0	—	unknown	—	72.5° 14:25	6.27	60%	118.8°
2040-05-03 Thu	0	—	unknown	—	72.5° 14:20	6.21	49%	104.7°
2040-05-04 Fri	0	—	unknown	—	72.5° 14:20	6.16	38%	90.9°
2040-05-05 Sat	0	—	unknown	—	72.5° 14:15	6.1	27%	77.2°
2040-05-06 Sun	0	—	unknown	—	72.5° 14:10	6.04	18%	63.8°
2040-05-07 Mon	0	—	unknown	—	72.5° 14:05	5.98	11%	50.6°
2040-05-08 Tue	0	—	unknown	—	72.5° 14:00	5.93	5%	37.6°
2040-05-09 Wed	0	—	unknown	—	72.5° 14:00	5.87	2%	24.9°
2040-05-10 Thu	0	—	unknown	—	72.5° 13:55	5.82	0%	12.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-04-11&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.