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.

2039-09-04astronomy score per night — click a bar for that night2039-10-03

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2039-09-23 Fri	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 05:00	8.78	36%	165.2°
2039-09-24 Sat	100	—	unknown	23:50–05:40 (good, 5.83 h)	72.5° 04:55	8.83	47%	151.5°
2039-09-25 Sun	100	—	unknown	23:50–05:40 (good, 5.83 h)	72.5° 04:50	8.88	58%	137.6°
2039-09-26 Mon	100	—	unknown	23:45–05:45 (good, 6.0 h)	72.5° 04:45	8.93	69%	123.7°
2039-09-27 Tue	100	—	unknown	23:50–05:45 (good, 5.92 h)	72.5° 04:45	8.98	79%	109.9°
2039-09-28 Wed	100	—	unknown	23:55–05:45 (good, 5.83 h)	72.5° 04:40	9.03	87%	96.3°
2039-09-29 Thu	100	—	unknown	00:45–05:45 (good, 5.0 h)	72.5° 04:35	9.08	94%	82.8°
2039-09-30 Fri	73	—	unknown	02:20–05:45 (good, 3.42 h)	72.5° 04:30	9.12	98%	69.5°
2039-10-01 Sat	55	—	unknown	05:20–05:50 (good, 0.5 h)	72.5° 04:25	9.17	100%	56.4°
2039-10-02 Sun	35	—	unknown	23:30–05:50 (marginal, 6.33 h)	72.5° 04:25	9.22	100%	43.6°
2039-10-03 Mon	22	—	unknown	03:15–05:50 (marginal, 2.58 h)	72.5° 04:20	9.27	97%	31.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-09-04&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.