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: 04-09 (2), 04-10 (1), 04-11 (1), 04-12 (1), 04-13 (1) — by astronomy; check the weather when the night is within four days.

2029-04-09astronomy score per night — click a bar for that night2029-05-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2029-04-09 Mon	2	—	unknown	21:00–21:10 (marginal, 0.17 h)	72.5° 15:55	7.62	14%	82.5°
2029-04-10 Tue	1	—	unknown	21:00–21:05 (marginal, 0.08 h)	72.5° 15:55	7.56	8%	70.6°
2029-04-11 Wed	1	—	unknown	—	72.5° 15:50	7.51	4%	58.7°
2029-04-12 Thu	1	—	unknown	—	72.5° 15:45	7.45	1%	46.9°
2029-04-13 Fri	1	—	unknown	—	72.5° 15:40	7.39	0%	35.1°
2029-04-14 Sat	1	—	unknown	—	72.5° 15:35	7.33	1%	23.2°
2029-04-15 Sun	0	—	unknown	—	72.5° 15:35	7.28	4%	11.3°
2029-04-16 Mon	0	—	unknown	—	72.5° 15:30	7.22	8%	1.3°
2029-04-17 Tue	0	—	unknown	—	72.5° 15:25	7.16	14%	12.9°
2029-04-18 Wed	0	—	unknown	—	72.5° 15:20	7.1	22%	25.3°
2029-04-19 Thu	0	—	unknown	—	72.5° 15:20	7.05	31%	37.8°
2029-04-20 Fri	0	—	unknown	—	72.5° 15:15	6.99	40%	50.7°
2029-04-21 Sat	0	—	unknown	—	72.5° 15:10	6.93	51%	63.9°
2029-04-22 Sun	0	—	unknown	—	72.5° 15:05	6.87	62%	77.5°
2029-04-23 Mon	0	—	unknown	—	72.5° 15:00	6.81	73%	91.5°
2029-04-24 Tue	0	—	unknown	—	72.5° 15:00	6.75	82%	105.9°
2029-04-25 Wed	0	—	unknown	—	72.5° 14:55	6.7	90%	120.7°
2029-04-26 Thu	0	—	unknown	—	72.5° 14:50	6.64	96%	135.8°
2029-04-27 Fri	0	—	unknown	—	72.5° 14:45	6.58	99%	151.0°
2029-04-28 Sat	0	—	unknown	—	72.5° 14:40	6.52	100%	166.1°
2029-04-29 Sun	0	—	unknown	—	72.5° 14:40	6.46	97%	178.5°
2029-04-30 Mon	0	—	unknown	—	72.5° 14:35	6.41	91%	164.2°
2029-05-01 Tue	0	—	unknown	—	72.5° 14:30	6.35	84%	150.1°
2029-05-02 Wed	0	—	unknown	—	72.5° 14:25	6.29	75%	136.4°
2029-05-03 Thu	0	—	unknown	—	72.5° 14:25	6.23	65%	123.1°
2029-05-04 Fri	0	—	unknown	—	72.5° 14:20	6.17	55%	110.3°
2029-05-05 Sat	0	—	unknown	—	72.5° 14:15	6.12	45%	97.8°
2029-05-06 Sun	0	—	unknown	—	72.5° 14:10	6.06	35%	85.7°
2029-05-07 Mon	0	—	unknown	—	72.5° 14:05	6.0	26%	73.7°
2029-05-08 Tue	0	—	unknown	—	72.5° 14:05	5.95	19%	61.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2029-04-09&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.