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: 09-21 (100), 09-22 (100), 09-23 (100), 09-24 (100), 09-25 (100) — by astronomy; check the weather when the night is within four days.

2041-09-10astronomy score per night — click a bar for that night2041-10-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-09-10 Tue	41	—	unknown	05:15–05:25 (good, 0.17 h)	72.5° 05:50	8.13	100%	63.9°
2041-09-11 Wed	27	—	unknown	00:45–05:25 (marginal, 4.67 h)	72.5° 05:45	8.18	96%	48.8°
2041-09-12 Thu	18	—	unknown	00:50–05:25 (marginal, 4.58 h)	72.5° 05:40	8.23	91%	34.0°
2041-09-13 Fri	20	—	unknown	00:35–05:30 (marginal, 4.92 h)	72.5° 05:35	8.29	83%	19.6°
2041-09-14 Sat	28	—	unknown	00:15–05:30 (marginal, 5.25 h)	72.5° 05:30	8.34	74%	5.9°
2041-09-15 Sun	41	—	unknown	00:00–05:30 (marginal, 5.5 h)	72.5° 05:30	8.39	63%	8.2°
2041-09-16 Mon	57	—	unknown	01:15–05:10 (good, 3.92 h)	72.5° 05:25	8.44	53%	21.0°
2041-09-17 Tue	74	—	unknown	00:30–05:35 (good, 5.08 h)	72.5° 05:20	8.5	43%	33.6°
2041-09-18 Wed	84	—	unknown	00:10–05:35 (good, 5.42 h)	72.5° 05:15	8.55	33%	46.0°
2041-09-19 Thu	91	—	unknown	00:05–05:35 (good, 5.5 h)	72.5° 05:15	8.6	25%	58.1°
2041-09-20 Fri	98	—	unknown	00:05–05:35 (good, 5.5 h)	72.5° 05:10	8.65	17%	70.0°
2041-09-21 Sat	100	—	unknown	00:00–05:40 (good, 5.67 h)	72.5° 05:05	8.7	10%	81.8°
2041-09-22 Sun	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 05:00	8.75	5%	93.7°
2041-09-23 Mon	100	—	unknown	23:50–05:40 (good, 5.83 h)	72.5° 04:55	8.8	2%	105.5°
2041-09-24 Tue	100	—	unknown	23:45–05:40 (good, 5.92 h)	72.5° 04:55	8.85	0%	117.3°
2041-09-25 Wed	100	—	unknown	23:45–05:40 (good, 5.92 h)	72.5° 04:50	8.9	0%	129.2°
2041-09-26 Thu	100	—	unknown	23:40–05:45 (good, 6.08 h)	72.5° 04:45	8.95	2%	141.3°
2041-09-27 Fri	100	—	unknown	23:35–05:45 (good, 6.17 h)	72.5° 04:40	9.0	6%	153.4°
2041-09-28 Sat	100	—	unknown	23:30–05:45 (good, 6.25 h)	72.5° 04:35	9.05	12%	165.7°
2041-09-29 Sun	100	—	unknown	23:25–05:45 (good, 6.33 h)	72.5° 04:35	9.1	19%	177.4°
2041-09-30 Mon	100	—	unknown	23:25–05:50 (good, 6.42 h)	72.5° 04:30	9.15	27%	168.8°
2041-10-01 Tue	100	—	unknown	23:20–05:50 (good, 6.5 h)	72.5° 04:25	9.2	37%	155.9°
2041-10-02 Wed	100	—	unknown	23:15–05:50 (good, 6.58 h)	72.5° 04:20	9.24	48%	142.6°
2041-10-03 Thu	100	—	unknown	23:15–05:50 (good, 6.58 h)	72.5° 04:15	9.29	59%	128.9°
2041-10-04 Fri	100	—	unknown	23:15–05:50 (good, 6.58 h)	72.5° 04:15	9.34	70%	114.9°
2041-10-05 Sat	100	—	unknown	23:20–05:55 (good, 6.58 h)	72.5° 04:10	9.39	80%	100.5°
2041-10-06 Sun	100	—	unknown	23:45–05:55 (good, 6.17 h)	72.5° 04:05	9.43	88%	85.8°
2041-10-07 Mon	100	—	unknown	01:35–05:55 (good, 4.33 h)	72.5° 04:00	9.48	95%	70.8°
2041-10-08 Tue	63	—	unknown	04:55–05:55 (good, 1.0 h)	72.5° 04:00	9.53	99%	55.8°
2041-10-09 Wed	37	—	unknown	23:10–06:00 (marginal, 6.83 h)	72.5° 03:55	9.57	100%	40.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-09-10&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.