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: 09-12 (100), 09-13 (100), 09-14 (100), 09-15 (100), 09-16 (100) — by astronomy; check the weather when the night is within four days.

2031-09-04astronomy score per night — click a bar for that night2031-10-03

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-09-04 Thu	16	—	unknown	01:20–05:15 (marginal, 3.92 h)	72.5° 06:15	7.77	84%	31.1°
2031-09-05 Fri	21	—	unknown	01:00–05:15 (marginal, 4.25 h)	72.5° 06:10	7.82	76%	18.3°
2031-09-06 Sat	31	—	unknown	00:40–05:20 (marginal, 4.67 h)	72.5° 06:05	7.88	67%	6.9°
2031-09-07 Sun	43	—	unknown	00:30–05:20 (marginal, 4.83 h)	72.5° 06:00	7.93	57%	8.9°
2031-09-08 Mon	57	—	unknown	01:15–05:20 (good, 4.08 h)	72.5° 05:55	7.99	48%	20.1°
2031-09-09 Tue	73	—	unknown	00:50–05:20 (good, 4.5 h)	72.5° 05:55	8.04	38%	31.9°
2031-09-10 Wed	86	—	unknown	00:45–05:25 (good, 4.67 h)	72.5° 05:50	8.09	29%	43.6°
2031-09-11 Thu	93	—	unknown	00:40–05:25 (good, 4.75 h)	72.5° 05:45	8.15	21%	55.3°
2031-09-12 Fri	100	—	unknown	00:35–05:25 (good, 4.83 h)	72.5° 05:40	8.2	14%	67.2°
2031-09-13 Sat	100	—	unknown	00:30–05:25 (good, 4.92 h)	72.5° 05:40	8.26	8%	79.1°
2031-09-14 Sun	100	—	unknown	00:30–05:30 (good, 5.0 h)	72.5° 05:35	8.31	4%	91.2°
2031-09-15 Mon	100	—	unknown	00:25–05:30 (good, 5.08 h)	72.5° 05:30	8.36	1%	103.5°
2031-09-16 Tue	100	—	unknown	00:20–05:30 (good, 5.17 h)	72.5° 05:25	8.41	0%	116.0°
2031-09-17 Wed	100	—	unknown	00:15–05:30 (good, 5.25 h)	72.5° 05:20	8.47	2%	128.7°
2031-09-18 Thu	100	—	unknown	00:10–05:35 (good, 5.42 h)	72.5° 05:20	8.52	5%	141.6°
2031-09-19 Fri	100	—	unknown	00:10–05:35 (good, 5.42 h)	72.5° 05:15	8.57	10%	154.6°
2031-09-20 Sat	100	—	unknown	00:05–05:35 (good, 5.5 h)	72.5° 05:10	8.62	18%	167.4°
2031-09-21 Sun	100	—	unknown	00:00–05:35 (good, 5.58 h)	72.5° 05:05	8.67	27%	174.6°
2031-09-22 Mon	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 05:00	8.72	37%	163.4°
2031-09-23 Tue	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 05:00	8.77	48%	149.9°
2031-09-24 Wed	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 04:55	8.82	60%	135.9°
2031-09-25 Thu	100	—	unknown	23:50–05:40 (good, 5.83 h)	72.5° 04:50	8.87	71%	121.7°
2031-09-26 Fri	100	—	unknown	23:55–05:45 (good, 5.83 h)	72.5° 04:45	8.92	81%	107.4°
2031-09-27 Sat	100	—	unknown	00:05–05:45 (good, 5.67 h)	72.5° 04:45	8.97	89%	93.0°
2031-09-28 Sun	100	—	unknown	01:35–05:45 (good, 4.17 h)	72.5° 04:40	9.02	95%	78.6°
2031-09-29 Mon	63	—	unknown	04:05–05:45 (good, 1.67 h)	72.5° 04:35	9.07	99%	64.4°
2031-09-30 Tue	40	—	unknown	23:40–05:45 (marginal, 6.08 h)	72.5° 04:30	9.12	100%	50.4°
2031-10-01 Wed	25	—	unknown	02:00–05:50 (marginal, 3.83 h)	72.5° 04:25	9.17	98%	36.7°
2031-10-02 Thu	19	—	unknown	04:15–05:50 (marginal, 1.58 h)	72.5° 04:25	9.22	95%	23.4°
2031-10-03 Fri	22	—	unknown	23:20–05:50 (marginal, 6.5 h)	72.5° 04:20	9.27	89%	11.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-09-04&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.