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: 09-15 (100), 09-16 (100), 09-17 (100), 09-18 (100), 09-19 (100) — by astronomy; check the weather when the night is within four days.

2039-08-24astronomy score per night — click a bar for that night2039-09-22

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-08-24 Wed	84	—	unknown	01:50–05:00 (good, 3.17 h)	72.5° 06:55	7.15	28%	154.2°
2039-08-25 Thu	86	—	unknown	01:45–05:00 (good, 3.25 h)	72.5° 06:55	7.21	38%	167.4°
2039-08-26 Fri	89	—	unknown	01:45–05:05 (good, 3.33 h)	72.5° 06:50	7.26	50%	173.6°
2039-08-27 Sat	91	—	unknown	01:40–05:05 (good, 3.42 h)	72.5° 06:45	7.32	61%	162.0°
2039-08-28 Sun	93	—	unknown	01:35–05:05 (good, 3.5 h)	72.5° 06:40	7.38	72%	148.2°
2039-08-29 Mon	95	—	unknown	01:35–05:10 (good, 3.58 h)	72.5° 06:35	7.43	82%	134.2°
2039-08-30 Tue	94	—	unknown	01:35–05:10 (good, 3.58 h)	72.5° 06:35	7.49	90%	120.0°
2039-08-31 Wed	88	—	unknown	01:40–05:10 (good, 3.5 h)	72.5° 06:30	7.55	95%	105.9°
2039-09-01 Thu	63	—	unknown	02:00–05:10 (good, 3.17 h)	72.5° 06:25	7.6	99%	92.0°
2039-09-02 Fri	49	—	unknown	03:20–05:15 (good, 1.92 h)	72.5° 06:20	7.66	100%	78.3°
2039-09-03 Sat	36	—	unknown	01:00–05:15 (marginal, 4.25 h)	72.5° 06:15	7.71	98%	64.9°
2039-09-04 Sun	26	—	unknown	01:05–05:15 (marginal, 4.17 h)	72.5° 06:15	7.77	95%	51.8°
2039-09-05 Mon	20	—	unknown	01:10–05:15 (marginal, 4.08 h)	72.5° 06:10	7.82	89%	39.1°
2039-09-06 Tue	19	—	unknown	01:00–05:20 (marginal, 4.33 h)	72.5° 06:05	7.88	82%	26.8°
2039-09-07 Wed	25	—	unknown	00:45–05:20 (marginal, 4.58 h)	72.5° 06:00	7.93	74%	15.1°
2039-09-08 Thu	34	—	unknown	00:30–05:20 (marginal, 4.83 h)	72.5° 06:00	7.99	65%	6.0°
2039-09-09 Fri	46	—	unknown	03:30–04:15 (good, 0.75 h)	72.5° 05:55	8.04	56%	11.4°
2039-09-10 Sat	60	—	unknown	01:05–05:25 (good, 4.33 h)	72.5° 05:50	8.1	47%	22.5°
2039-09-11 Sun	77	—	unknown	00:55–05:25 (good, 4.5 h)	72.5° 05:45	8.15	37%	34.1°
2039-09-12 Mon	87	—	unknown	00:35–05:25 (good, 4.83 h)	72.5° 05:40	8.2	28%	45.9°
2039-09-13 Tue	93	—	unknown	00:30–05:25 (good, 4.92 h)	72.5° 05:40	8.26	20%	58.0°
2039-09-14 Wed	99	—	unknown	00:30–05:30 (good, 5.0 h)	72.5° 05:35	8.31	13%	70.3°
2039-09-15 Thu	100	—	unknown	00:25–05:30 (good, 5.08 h)	72.5° 05:30	8.36	7%	83.0°
2039-09-16 Fri	100	—	unknown	00:20–05:30 (good, 5.17 h)	72.5° 05:25	8.42	3%	96.0°
2039-09-17 Sat	100	—	unknown	00:15–05:30 (good, 5.25 h)	72.5° 05:20	8.47	0%	109.3°
2039-09-18 Sun	100	—	unknown	00:10–05:35 (good, 5.42 h)	72.5° 05:20	8.52	1%	122.9°
2039-09-19 Mon	100	—	unknown	00:10–05:35 (good, 5.42 h)	72.5° 05:15	8.57	3%	136.7°
2039-09-20 Tue	100	—	unknown	00:05–05:35 (good, 5.5 h)	72.5° 05:10	8.62	8%	150.6°
2039-09-21 Wed	100	—	unknown	00:00–05:35 (good, 5.58 h)	72.5° 05:05	8.68	16%	164.3°
2039-09-22 Thu	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 05:05	8.73	25%	174.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-08-24&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.