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: 09-18 (100), 09-19 (100), 09-20 (100), 09-21 (100), 09-22 (100) — by astronomy; check the weather when the night is within four days.

2041-09-18astronomy score per night — click a bar for that night2041-10-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-09-18 Wed	100	—	unknown	21:00–02:35 (good, 5.58 h)	71.1° 21:30	8.55	33%	128.6°
2041-09-19 Thu	100	—	unknown	21:00–02:30 (good, 5.5 h)	71.1° 21:25	8.6	25%	131.7°
2041-09-20 Fri	100	—	unknown	20:55–02:30 (good, 5.58 h)	71.1° 21:25	8.65	17%	132.6°
2041-09-21 Sat	100	—	unknown	20:55–02:25 (good, 5.5 h)	71.1° 21:20	8.7	10%	131.3°
2041-09-22 Sun	100	—	unknown	20:55–02:20 (good, 5.42 h)	71.1° 21:15	8.75	5%	128.0°
2041-09-23 Mon	100	—	unknown	20:50–02:20 (good, 5.5 h)	71.1° 21:10	8.8	2%	123.0°
2041-09-24 Tue	100	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:10	8.85	0%	116.7°
2041-09-25 Wed	100	—	unknown	20:50–02:10 (good, 5.33 h)	71.1° 21:05	8.9	0%	109.6°
2041-09-26 Thu	100	—	unknown	20:45–02:05 (good, 5.33 h)	71.1° 21:00	8.95	2%	101.8°
2041-09-27 Fri	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 20:55	9.0	6%	93.7°
2041-09-28 Sat	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 20:50	9.05	12%	85.4°
2041-09-29 Sun	100	—	unknown	20:40–01:55 (good, 5.25 h)	71.1° 20:50	9.1	19%	77.0°
2041-09-30 Mon	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:45	9.15	27%	68.9°
2041-10-01 Tue	100	—	unknown	20:35–01:45 (good, 5.17 h)	71.1° 20:40	9.2	37%	61.4°
2041-10-02 Wed	96	—	unknown	20:35–01:45 (good, 5.17 h)	71.1° 20:35	9.24	48%	54.8°
2041-10-03 Thu	87	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:30	9.29	59%	49.9°
2041-10-04 Fri	64	—	unknown	20:30–01:10 (good, 4.67 h)	71.1° 20:30	9.34	70%	47.5°
2041-10-05 Sat	51	—	unknown	20:30–22:40 (good, 2.17 h)	71.1° 20:25	9.39	80%	48.3°
2041-10-06 Sun	45	—	unknown	19:55–01:40 (marginal, 5.75 h)	71.1° 20:20	9.43	88%	52.3°
2041-10-07 Mon	44	—	unknown	20:25–20:40 (good, 0.25 h)	71.1° 20:15	9.48	95%	58.9°
2041-10-08 Tue	47	—	unknown	20:25–21:35 (good, 1.17 h)	71.1° 20:15	9.53	99%	67.3°
2041-10-09 Wed	55	—	unknown	20:25–22:35 (good, 2.17 h)	71.1° 20:10	9.57	100%	76.8°
2041-10-10 Thu	68	—	unknown	20:20–23:30 (good, 3.17 h)	71.1° 20:05	9.62	98%	86.7°
2041-10-11 Fri	81	—	unknown	20:20–00:25 (good, 4.08 h)	71.1° 20:00	9.66	94%	96.5°
2041-10-12 Sat	100	—	unknown	20:20–00:45 (good, 4.42 h)	71.1° 19:55	9.71	87%	105.7°
2041-10-13 Sun	100	—	unknown	20:15–00:50 (good, 4.58 h)	71.1° 19:55	9.75	78%	114.2°
2041-10-14 Mon	100	—	unknown	20:15–00:50 (good, 4.58 h)	71.1° 19:50	9.79	69%	121.4°
2041-10-15 Tue	100	—	unknown	20:15–00:45 (good, 4.5 h)	71.1° 19:45	9.84	60%	127.1°
2041-10-16 Wed	100	—	unknown	20:15–00:45 (good, 4.5 h)	71.1° 19:40	9.88	50%	130.9°
2041-10-17 Thu	100	—	unknown	20:10–00:45 (good, 4.58 h)	71.1° 19:35	9.92	40%	132.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-09-18&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.