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: 07-27 (100), 07-28 (100), 07-29 (100), 07-30 (100), 07-31 (100) — by astronomy; check the weather when the night is within four days.

2039-07-27astronomy score per night — click a bar for that night2039-08-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-07-27 Wed	100	—	unknown	22:45–04:15 (good, 5.5 h)	71.1° 01:00	5.57	41%	97.6°
2039-07-28 Thu	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 01:00	5.62	52%	88.0°
2039-07-29 Fri	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 00:55	5.68	64%	78.3°
2039-07-30 Sat	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 00:50	5.73	74%	68.8°
2039-07-31 Sun	100	—	unknown	22:35–04:25 (good, 5.83 h)	71.1° 00:45	5.78	84%	60.0°
2039-08-01 Mon	93	—	unknown	00:00–04:25 (good, 4.42 h)	71.1° 00:40	5.84	92%	52.7°
2039-08-02 Tue	57	—	unknown	22:35–04:25 (marginal, 5.83 h)	71.1° 00:40	5.89	97%	47.7°
2039-08-03 Wed	50	—	unknown	22:30–04:30 (marginal, 6.0 h)	71.1° 00:35	5.95	100%	45.9°
2039-08-04 Thu	52	—	unknown	22:30–04:30 (marginal, 6.0 h)	71.1° 00:30	6.01	100%	47.5°
2039-08-05 Fri	61	—	unknown	22:30–23:35 (good, 1.08 h)	71.1° 00:25	6.06	97%	52.2°
2039-08-06 Sat	72	—	unknown	22:25–01:15 (good, 2.83 h)	71.1° 00:20	6.12	92%	58.8°
2039-08-07 Sun	100	—	unknown	22:25–02:50 (good, 4.42 h)	71.1° 00:20	6.18	85%	66.6°
2039-08-08 Mon	100	—	unknown	22:20–03:55 (good, 5.58 h)	71.1° 00:15	6.23	77%	75.0°
2039-08-09 Tue	100	—	unknown	22:20–04:40 (good, 6.33 h)	71.1° 00:10	6.29	68%	83.5°
2039-08-10 Wed	100	—	unknown	22:20–04:40 (good, 6.33 h)	71.1° 00:05	6.35	58%	92.0°
2039-08-11 Thu	100	—	unknown	22:15–04:40 (good, 6.42 h)	71.1° 00:05	6.4	49%	100.3°
2039-08-12 Fri	100	—	unknown	22:15–04:45 (good, 6.5 h)	71.1° 00:00	6.46	40%	108.3°
2039-08-13 Sat	100	—	unknown	22:15–04:45 (good, 6.5 h)	71.1° 23:55	6.52	30%	115.8°
2039-08-14 Sun	100	—	unknown	22:10–04:45 (good, 6.58 h)	71.1° 23:50	6.58	22%	122.5°
2039-08-15 Mon	100	—	unknown	22:10–04:45 (good, 6.58 h)	71.1° 23:45	6.63	15%	128.1°
2039-08-16 Tue	100	—	unknown	22:05–04:50 (good, 6.75 h)	71.1° 23:45	6.69	9%	132.2°
2039-08-17 Wed	100	—	unknown	22:05–04:45 (good, 6.67 h)	71.1° 23:40	6.75	4%	134.0°
2039-08-18 Thu	100	—	unknown	22:05–04:40 (good, 6.58 h)	71.1° 23:35	6.81	1%	133.4°
2039-08-19 Fri	100	—	unknown	22:00–04:40 (good, 6.67 h)	71.1° 23:30	6.86	0%	130.1°
2039-08-20 Sat	100	—	unknown	22:00–04:35 (good, 6.58 h)	71.1° 23:25	6.92	1%	124.6°
2039-08-21 Sun	100	—	unknown	22:00–04:30 (good, 6.5 h)	71.1° 23:25	6.98	5%	117.5°
2039-08-22 Mon	100	—	unknown	21:55–04:25 (good, 6.5 h)	71.1° 23:20	7.04	11%	109.1°
2039-08-23 Tue	100	—	unknown	21:55–04:20 (good, 6.42 h)	71.1° 23:15	7.09	18%	99.9°
2039-08-24 Wed	100	—	unknown	21:50–04:20 (good, 6.5 h)	71.1° 23:10	7.15	28%	90.4°
2039-08-25 Thu	100	—	unknown	21:50–04:15 (good, 6.42 h)	71.1° 23:10	7.21	38%	80.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-07-27&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.