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 HD 189733: 09-05 (100), 09-06 (100), 09-07 (100), 09-08 (100), 09-09 (100) — by astronomy; check the weather when the night is within four days.

2039-09-03astronomy score per night — click a bar for that night2039-10-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-09-03 Sat	64	—	unknown	21:30–23:25 (good, 1.92 h)	71.1° 22:30	7.71	98%	63.4°
2039-09-04 Sun	75	—	unknown	21:30–00:50 (good, 3.33 h)	71.1° 22:30	7.77	95%	71.6°
2039-09-05 Mon	100	—	unknown	21:30–01:45 (good, 4.25 h)	71.1° 22:25	7.82	89%	80.2°
2039-09-06 Tue	100	—	unknown	21:25–02:40 (good, 5.25 h)	71.1° 22:20	7.88	82%	88.8°
2039-09-07 Wed	100	—	unknown	21:25–03:00 (good, 5.58 h)	71.1° 22:15	7.93	74%	97.3°
2039-09-08 Thu	100	—	unknown	21:20–03:05 (good, 5.75 h)	71.1° 22:15	7.99	65%	105.5°
2039-09-09 Fri	100	—	unknown	21:20–03:05 (good, 5.75 h)	71.1° 22:10	8.04	56%	113.2°
2039-09-10 Sat	100	—	unknown	21:20–03:05 (good, 5.75 h)	71.1° 22:05	8.1	47%	120.2°
2039-09-11 Sun	100	—	unknown	21:15–03:05 (good, 5.83 h)	71.1° 22:00	8.15	37%	126.2°
2039-09-12 Mon	100	—	unknown	21:15–03:00 (good, 5.75 h)	71.1° 21:55	8.2	28%	130.8°
2039-09-13 Tue	100	—	unknown	21:10–03:00 (good, 5.83 h)	71.1° 21:55	8.26	20%	133.5°
2039-09-14 Wed	100	—	unknown	21:10–02:55 (good, 5.75 h)	71.1° 21:50	8.31	13%	133.8°
2039-09-15 Thu	100	—	unknown	21:10–02:50 (good, 5.67 h)	71.1° 21:45	8.36	7%	131.5°
2039-09-16 Fri	100	—	unknown	21:05–02:45 (good, 5.67 h)	71.1° 21:40	8.42	3%	126.7°
2039-09-17 Sat	100	—	unknown	21:05–02:45 (good, 5.67 h)	71.1° 21:35	8.47	0%	120.0°
2039-09-18 Sun	100	—	unknown	21:00–02:40 (good, 5.67 h)	71.1° 21:35	8.52	1%	111.9°
2039-09-19 Mon	100	—	unknown	21:00–02:35 (good, 5.58 h)	71.1° 21:30	8.57	3%	102.7°
2039-09-20 Tue	100	—	unknown	21:00–02:30 (good, 5.5 h)	71.1° 21:25	8.62	8%	93.1°
2039-09-21 Wed	100	—	unknown	20:55–02:30 (good, 5.58 h)	71.1° 21:20	8.68	16%	83.2°
2039-09-22 Thu	100	—	unknown	20:55–02:25 (good, 5.5 h)	71.1° 21:20	8.73	25%	73.6°
2039-09-23 Fri	100	—	unknown	20:55–02:20 (good, 5.42 h)	71.1° 21:15	8.78	36%	64.6°
2039-09-24 Sat	98	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:10	8.83	47%	56.6°
2039-09-25 Sun	92	—	unknown	20:50–02:10 (good, 5.33 h)	71.1° 21:05	8.88	58%	50.5°
2039-09-26 Mon	83	—	unknown	20:45–02:10 (good, 5.42 h)	71.1° 21:00	8.93	69%	46.9°
2039-09-27 Tue	55	—	unknown	20:45–23:40 (good, 2.92 h)	71.1° 21:00	8.98	79%	46.3°
2039-09-28 Wed	48	—	unknown	20:45–02:20 (marginal, 5.58 h)	71.1° 20:55	9.03	87%	48.8°
2039-09-29 Thu	46	—	unknown	20:40–02:10 (marginal, 5.5 h)	71.1° 20:50	9.08	94%	53.9°
2039-09-30 Fri	48	—	unknown	20:40–21:15 (good, 0.58 h)	71.1° 20:45	9.12	98%	60.7°
2039-10-01 Sat	53	—	unknown	20:40–22:20 (good, 1.67 h)	71.1° 20:40	9.17	100%	68.6°
2039-10-02 Sun	62	—	unknown	20:35–23:10 (good, 2.58 h)	71.1° 20:40	9.22	100%	77.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-09-03&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.