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: 09-27 (100), 09-28 (100), 09-29 (100), 09-30 (100), 10-01 (100) — by astronomy; check the weather when the night is within four days.

2037-09-27astronomy score per night — click a bar for that night2037-10-26

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-09-27 Sun	100	—	unknown	20:45–01:30 (good, 4.75 h)	71.1° 20:55	9.0	89%	96.3°
2037-09-28 Mon	100	—	unknown	20:45–01:40 (good, 4.92 h)	71.1° 20:50	9.05	83%	105.1°
2037-09-29 Tue	100	—	unknown	20:40–01:45 (good, 5.08 h)	71.1° 20:50	9.1	75%	113.6°
2037-09-30 Wed	100	—	unknown	20:40–01:45 (good, 5.08 h)	71.1° 20:45	9.15	66%	121.5°
2037-10-01 Thu	100	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:40	9.2	55%	128.6°
2037-10-02 Fri	100	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:35	9.24	45%	133.9°
2037-10-03 Sat	100	—	unknown	20:35–01:35 (good, 5.0 h)	71.1° 20:30	9.29	34%	136.7°
2037-10-04 Sun	100	—	unknown	20:30–01:35 (good, 5.08 h)	71.1° 20:30	9.34	24%	136.0°
2037-10-05 Mon	100	—	unknown	20:30–01:30 (good, 5.0 h)	71.1° 20:25	9.38	15%	131.8°
2037-10-06 Tue	100	—	unknown	20:30–01:25 (good, 4.92 h)	71.1° 20:20	9.43	7%	124.7°
2037-10-07 Wed	100	—	unknown	20:25–01:25 (good, 5.0 h)	71.1° 20:15	9.48	2%	115.5°
2037-10-08 Thu	100	—	unknown	20:25–01:20 (good, 4.92 h)	71.1° 20:15	9.52	0%	105.1°
2037-10-09 Fri	100	—	unknown	20:25–01:15 (good, 4.83 h)	71.1° 20:10	9.57	1%	94.2°
2037-10-10 Sat	100	—	unknown	20:20–01:10 (good, 4.83 h)	71.1° 20:05	9.61	5%	83.3°
2037-10-11 Sun	100	—	unknown	20:20–01:05 (good, 4.75 h)	71.1° 20:00	9.66	11%	72.9°
2037-10-12 Mon	100	—	unknown	20:20–01:05 (good, 4.75 h)	71.1° 19:55	9.7	20%	63.3°
2037-10-13 Tue	98	—	unknown	20:15–01:00 (good, 4.75 h)	71.1° 19:55	9.75	29%	55.1°
2037-10-14 Wed	91	—	unknown	20:15–00:55 (good, 4.67 h)	71.1° 19:50	9.79	39%	48.7°
2037-10-15 Thu	84	—	unknown	20:15–00:50 (good, 4.58 h)	71.1° 19:45	9.84	49%	44.6°
2037-10-16 Fri	62	—	unknown	20:15–00:25 (good, 4.17 h)	71.1° 19:40	9.88	59%	43.2°
2037-10-17 Sat	51	—	unknown	20:10–23:05 (good, 2.92 h)	71.1° 19:35	9.92	68%	44.6°
2037-10-18 Sun	44	—	unknown	20:10–21:35 (good, 1.42 h)	71.1° 19:35	9.96	77%	48.4°
2037-10-19 Mon	42	—	unknown	20:10–20:30 (good, 0.33 h)	71.1° 19:30	10.01	84%	53.9°
2037-10-20 Tue	42	—	unknown	20:05–20:45 (good, 0.67 h)	71.1° 19:25	10.05	90%	60.8°
2037-10-21 Wed	44	—	unknown	20:05–21:25 (good, 1.33 h)	71.1° 19:20	10.09	95%	68.5°
2037-10-22 Thu	49	—	unknown	20:05–21:55 (good, 1.83 h)	71.1° 19:20	10.13	98%	76.7°
2037-10-23 Fri	56	—	unknown	20:05–22:30 (good, 2.42 h)	71.1° 19:15	10.17	100%	85.3°
2037-10-24 Sat	66	—	unknown	20:00–23:15 (good, 3.25 h)	71.1° 19:10	10.21	99%	94.1°
2037-10-25 Sun	75	—	unknown	19:00–22:50 (good, 3.83 h)	71.1° 18:05	10.25	97%	102.9°
2037-10-26 Mon	95	—	unknown	19:00–22:50 (good, 3.83 h)	71.1° 18:00	10.29	93%	111.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-09-27&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.