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: 08-20 (100), 08-21 (100), 08-22 (100), 08-23 (100), 08-24 (100) — by astronomy; check the weather when the night is within four days.

2042-08-20astronomy score per night — click a bar for that night2042-09-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-08-20 Wed	100	—	unknown	22:00–04:35 (good, 6.58 h)	71.1° 23:25	6.94	23%	100.2°
2042-08-21 Thu	100	—	unknown	21:55–04:30 (good, 6.58 h)	71.1° 23:20	6.99	32%	92.2°
2042-08-22 Fri	100	—	unknown	21:55–04:25 (good, 6.5 h)	71.1° 23:20	7.05	41%	84.1°
2042-08-23 Sat	100	—	unknown	21:55–04:20 (good, 6.42 h)	71.1° 23:15	7.11	50%	76.0°
2042-08-24 Sun	100	—	unknown	21:50–04:15 (good, 6.42 h)	71.1° 23:10	7.17	60%	68.2°
2042-08-25 Mon	100	—	unknown	21:50–04:15 (good, 6.42 h)	71.1° 23:05	7.22	70%	60.8°
2042-08-26 Tue	94	—	unknown	21:45–04:10 (good, 6.42 h)	71.1° 23:05	7.28	79%	54.4°
2042-08-27 Wed	86	—	unknown	21:45–04:05 (good, 6.33 h)	71.1° 23:00	7.34	87%	49.5°
2042-08-28 Thu	56	—	unknown	21:45–04:30 (marginal, 6.75 h)	71.1° 22:55	7.39	94%	47.1°
2042-08-29 Fri	50	—	unknown	21:40–04:10 (marginal, 6.5 h)	71.1° 22:50	7.45	98%	47.8°
2042-08-30 Sat	50	—	unknown	21:40–04:00 (marginal, 6.33 h)	71.1° 22:45	7.51	100%	51.8°
2042-08-31 Sun	58	—	unknown	21:35–22:35 (good, 1.0 h)	71.1° 22:45	7.56	99%	58.4°
2042-09-01 Mon	70	—	unknown	21:35–00:15 (good, 2.67 h)	71.1° 22:40	7.62	95%	66.8°
2042-09-02 Tue	78	—	unknown	21:35–01:30 (good, 3.92 h)	71.1° 22:35	7.67	88%	76.2°
2042-09-03 Wed	100	—	unknown	21:30–02:40 (good, 5.17 h)	71.1° 22:30	7.73	80%	86.1°
2042-09-04 Thu	100	—	unknown	21:30–03:15 (good, 5.75 h)	71.1° 22:25	7.78	70%	96.0°
2042-09-05 Fri	100	—	unknown	21:25–03:15 (good, 5.83 h)	71.1° 22:25	7.84	59%	105.4°
2042-09-06 Sat	100	—	unknown	21:25–03:20 (good, 5.92 h)	71.1° 22:20	7.89	48%	114.0°
2042-09-07 Sun	100	—	unknown	21:25–03:20 (good, 5.92 h)	71.1° 22:15	7.95	37%	121.5°
2042-09-08 Mon	100	—	unknown	21:20–03:15 (good, 5.92 h)	71.1° 22:10	8.0	27%	127.5°
2042-09-09 Tue	100	—	unknown	21:20–03:15 (good, 5.92 h)	71.1° 22:10	8.06	18%	131.4°
2042-09-10 Wed	100	—	unknown	21:15–03:10 (good, 5.92 h)	71.1° 22:05	8.11	11%	133.0°
2042-09-11 Thu	100	—	unknown	21:15–03:05 (good, 5.83 h)	71.1° 22:00	8.17	6%	131.9°
2042-09-12 Fri	100	—	unknown	21:15–03:00 (good, 5.75 h)	71.1° 21:55	8.22	2%	128.7°
2042-09-13 Sat	100	—	unknown	21:10–03:00 (good, 5.83 h)	71.1° 21:50	8.27	0%	123.6°
2042-09-14 Sun	100	—	unknown	21:10–02:55 (good, 5.75 h)	71.1° 21:50	8.33	0%	117.3°
2042-09-15 Mon	100	—	unknown	21:05–02:50 (good, 5.75 h)	71.1° 21:45	8.38	2%	110.2°
2042-09-16 Tue	100	—	unknown	21:05–02:45 (good, 5.67 h)	71.1° 21:40	8.43	6%	102.6°
2042-09-17 Wed	100	—	unknown	21:05–02:45 (good, 5.67 h)	71.1° 21:35	8.48	11%	94.6°
2042-09-18 Thu	100	—	unknown	21:00–02:40 (good, 5.67 h)	71.1° 21:30	8.54	18%	86.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-08-20&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.