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: 08-12 (100), 08-13 (100), 08-14 (100), 08-15 (100), 08-16 (100) — by astronomy; check the weather when the night is within four days.

2037-08-12astronomy score per night — click a bar for that night2037-09-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-08-12 Wed	100	—	unknown	22:15–04:45 (good, 6.5 h)	71.1° 23:55	6.49	3%	125.5°
2037-08-13 Thu	100	—	unknown	22:10–04:45 (good, 6.58 h)	71.1° 23:55	6.55	9%	116.5°
2037-08-14 Fri	100	—	unknown	22:10–04:45 (good, 6.58 h)	71.1° 23:50	6.6	17%	106.4°
2037-08-15 Sat	100	—	unknown	22:10–04:50 (good, 6.67 h)	71.1° 23:45	6.66	27%	95.9°
2037-08-16 Sun	100	—	unknown	22:05–04:45 (good, 6.67 h)	71.1° 23:40	6.72	38%	85.5°
2037-08-17 Mon	100	—	unknown	22:05–04:45 (good, 6.67 h)	71.1° 23:35	6.78	49%	75.5°
2037-08-18 Tue	100	—	unknown	22:00–04:40 (good, 6.67 h)	71.1° 23:35	6.83	60%	66.2°
2037-08-19 Wed	99	—	unknown	22:00–04:35 (good, 6.58 h)	71.1° 23:30	6.89	70%	57.9°
2037-08-20 Thu	93	—	unknown	22:00–04:30 (good, 6.5 h)	71.1° 23:25	6.95	79%	50.9°
2037-08-21 Fri	87	—	unknown	00:25–04:30 (good, 4.08 h)	71.1° 23:20	7.01	86%	45.8°
2037-08-22 Sat	76	—	unknown	04:00–04:25 (good, 0.42 h)	71.1° 23:15	7.06	92%	43.2°
2037-08-23 Sun	47	—	unknown	21:55–04:35 (marginal, 6.67 h)	71.1° 23:15	7.12	97%	43.3°
2037-08-24 Mon	47	—	unknown	21:50–04:25 (marginal, 6.58 h)	71.1° 23:10	7.18	99%	46.0°
2037-08-25 Tue	51	—	unknown	21:50–04:20 (marginal, 6.5 h)	71.1° 23:05	7.24	100%	50.9°
2037-08-26 Wed	60	—	unknown	21:45–22:50 (good, 1.08 h)	71.1° 23:00	7.29	99%	57.3°
2037-08-27 Thu	71	—	unknown	21:45–00:20 (good, 2.58 h)	71.1° 23:00	7.35	96%	64.7°
2037-08-28 Fri	77	—	unknown	21:45–01:35 (good, 3.83 h)	71.1° 22:55	7.41	91%	72.8°
2037-08-29 Sat	100	—	unknown	21:40–02:30 (good, 4.83 h)	71.1° 22:50	7.46	85%	81.2°
2037-08-30 Sun	100	—	unknown	21:40–03:20 (good, 5.67 h)	71.1° 22:45	7.52	78%	89.9°
2037-08-31 Mon	100	—	unknown	21:35–03:30 (good, 5.92 h)	71.1° 22:40	7.57	69%	98.7°
2037-09-01 Tue	100	—	unknown	21:35–03:35 (good, 6.0 h)	71.1° 22:40	7.63	60%	107.5°
2037-09-02 Wed	100	—	unknown	21:35–03:35 (good, 6.0 h)	71.1° 22:35	7.69	50%	116.0°
2037-09-03 Thu	100	—	unknown	21:30–03:35 (good, 6.08 h)	71.1° 22:30	7.74	40%	123.9°
2037-09-04 Fri	100	—	unknown	21:30–03:30 (good, 6.0 h)	71.1° 22:25	7.8	29%	130.7°
2037-09-05 Sat	100	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:20	7.85	20%	135.5°
2037-09-06 Sun	100	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:20	7.91	12%	137.1°
2037-09-07 Mon	100	—	unknown	21:25–03:20 (good, 5.92 h)	71.1° 22:15	7.96	5%	134.8°
2037-09-08 Tue	100	—	unknown	21:20–03:15 (good, 5.92 h)	71.1° 22:10	8.02	1%	129.0°
2037-09-09 Wed	100	—	unknown	21:20–03:15 (good, 5.92 h)	71.1° 22:05	8.07	0%	120.6°
2037-09-10 Thu	100	—	unknown	21:15–03:10 (good, 5.92 h)	71.1° 22:05	8.12	2%	110.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-08-12&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.