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: 09-22 (100), 09-23 (100), 09-24 (100), 09-25 (100), 09-26 (100) — by astronomy; check the weather when the night is within four days.

2043-09-20astronomy score per night — click a bar for that night2043-10-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-09-20 Sun	69	—	unknown	21:00–00:00 (good, 3.0 h)	71.1° 21:25	8.63	95%	76.7°
2043-09-21 Mon	81	—	unknown	20:55–01:05 (good, 4.17 h)	71.1° 21:20	8.68	89%	86.7°
2043-09-22 Tue	100	—	unknown	20:55–02:00 (good, 5.08 h)	71.1° 21:20	8.73	81%	96.7°
2043-09-23 Wed	100	—	unknown	20:55–02:05 (good, 5.17 h)	71.1° 21:15	8.78	71%	106.5°
2043-09-24 Thu	100	—	unknown	20:50–02:10 (good, 5.33 h)	71.1° 21:10	8.83	60%	115.5°
2043-09-25 Fri	100	—	unknown	20:50–02:05 (good, 5.25 h)	71.1° 21:05	8.88	48%	123.3°
2043-09-26 Sat	100	—	unknown	20:45–02:05 (good, 5.33 h)	71.1° 21:00	8.93	37%	129.4°
2043-09-27 Sun	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 21:00	8.98	27%	133.0°
2043-09-28 Mon	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 20:55	9.03	18%	133.7°
2043-09-29 Tue	100	—	unknown	20:40–01:55 (good, 5.25 h)	71.1° 20:50	9.08	10%	131.5°
2043-09-30 Wed	100	—	unknown	20:40–01:55 (good, 5.25 h)	71.1° 20:45	9.13	5%	126.9°
2043-10-01 Thu	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:40	9.17	2%	120.7°
2043-10-02 Fri	100	—	unknown	20:35–01:45 (good, 5.17 h)	71.1° 20:40	9.22	0%	113.3°
2043-10-03 Sat	100	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:35	9.27	1%	105.3°
2043-10-04 Sun	100	—	unknown	20:35–01:35 (good, 5.0 h)	71.1° 20:30	9.32	3%	97.1°
2043-10-05 Mon	100	—	unknown	20:30–01:35 (good, 5.08 h)	71.1° 20:25	9.36	7%	88.7°
2043-10-06 Tue	100	—	unknown	20:30–01:30 (good, 5.0 h)	71.1° 20:25	9.41	13%	80.5°
2043-10-07 Wed	100	—	unknown	20:30–01:25 (good, 4.92 h)	71.1° 20:20	9.46	20%	72.6°
2043-10-08 Thu	100	—	unknown	20:25–01:20 (good, 4.92 h)	71.1° 20:15	9.5	28%	65.1°
2043-10-09 Fri	100	—	unknown	20:25–01:15 (good, 4.83 h)	71.1° 20:10	9.55	37%	58.4°
2043-10-10 Sat	93	—	unknown	20:25–01:15 (good, 4.83 h)	71.1° 20:05	9.59	46%	52.6°
2043-10-11 Sun	84	—	unknown	20:20–01:10 (good, 4.83 h)	71.1° 20:05	9.64	56%	48.4°
2043-10-12 Mon	61	—	unknown	20:20–00:40 (good, 4.33 h)	71.1° 20:00	9.68	66%	46.3°
2043-10-13 Tue	49	—	unknown	20:20–22:25 (good, 2.08 h)	71.1° 19:55	9.73	75%	46.8°
2043-10-14 Wed	42	—	unknown	20:15–01:15 (marginal, 5.0 h)	71.1° 19:50	9.77	84%	50.0°
2043-10-15 Thu	39	—	unknown	20:15–01:00 (marginal, 4.75 h)	71.1° 19:45	9.82	91%	55.8°
2043-10-16 Fri	40	—	unknown	20:15–20:25 (good, 0.17 h)	71.1° 19:45	9.86	96%	63.5°
2043-10-17 Sat	46	—	unknown	20:10–21:35 (good, 1.42 h)	71.1° 19:40	9.9	100%	72.6°
2043-10-18 Sun	56	—	unknown	20:10–22:30 (good, 2.33 h)	71.1° 19:35	9.94	100%	82.6°
2043-10-19 Mon	68	—	unknown	20:10–23:30 (good, 3.33 h)	71.1° 19:30	9.99	97%	93.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-09-20&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.