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: 09-23 (100), 09-24 (100), 09-25 (100), 09-26 (100), 09-27 (100) — by astronomy; check the weather when the night is within four days.

2040-09-19astronomy score per night — click a bar for that night2040-10-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-09-19 Wed	49	—	unknown	21:00–21:20 (good, 0.33 h)	71.1° 21:25	8.61	99%	58.2°
2040-09-20 Thu	56	—	unknown	20:55–22:30 (good, 1.58 h)	71.1° 21:25	8.66	100%	66.2°
2040-09-21 Fri	67	—	unknown	20:55–23:45 (good, 2.83 h)	71.1° 21:20	8.71	98%	75.2°
2040-09-22 Sat	79	—	unknown	20:55–00:40 (good, 3.75 h)	71.1° 21:15	8.77	94%	84.4°
2040-09-23 Sun	100	—	unknown	20:50–01:35 (good, 4.75 h)	71.1° 21:10	8.82	88%	93.6°
2040-09-24 Mon	100	—	unknown	20:50–01:55 (good, 5.08 h)	71.1° 21:05	8.87	80%	102.4°
2040-09-25 Tue	100	—	unknown	20:50–01:55 (good, 5.08 h)	71.1° 21:05	8.92	71%	110.5°
2040-09-26 Wed	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 21:00	8.97	62%	117.8°
2040-09-27 Thu	100	—	unknown	20:45–01:55 (good, 5.17 h)	71.1° 20:55	9.01	53%	124.1°
2040-09-28 Fri	100	—	unknown	20:40–01:55 (good, 5.25 h)	71.1° 20:50	9.06	43%	128.9°
2040-09-29 Sat	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:45	9.11	34%	132.0°
2040-09-30 Sun	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:45	9.16	25%	132.9°
2040-10-01 Mon	100	—	unknown	20:35–01:45 (good, 5.17 h)	71.1° 20:40	9.21	18%	131.6°
2040-10-02 Tue	100	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:35	9.26	11%	128.2°
2040-10-03 Wed	100	—	unknown	20:35–01:40 (good, 5.08 h)	71.1° 20:30	9.3	6%	122.9°
2040-10-04 Thu	100	—	unknown	20:30–01:35 (good, 5.08 h)	71.1° 20:25	9.35	2%	116.2°
2040-10-05 Fri	100	—	unknown	20:30–01:30 (good, 5.0 h)	71.1° 20:25	9.4	0%	108.4°
2040-10-06 Sat	100	—	unknown	20:30–01:25 (good, 4.92 h)	71.1° 20:20	9.44	1%	99.9°
2040-10-07 Sun	100	—	unknown	20:25–01:20 (good, 4.92 h)	71.1° 20:15	9.49	3%	91.0°
2040-10-08 Mon	100	—	unknown	20:25–01:20 (good, 4.92 h)	71.1° 20:10	9.54	8%	81.9°
2040-10-09 Tue	100	—	unknown	20:25–01:15 (good, 4.83 h)	71.1° 20:10	9.58	15%	72.9°
2040-10-10 Wed	100	—	unknown	20:20–01:10 (good, 4.83 h)	71.1° 20:05	9.63	24%	64.4°
2040-10-11 Thu	99	—	unknown	20:20–01:05 (good, 4.75 h)	71.1° 20:00	9.67	34%	57.0°
2040-10-12 Fri	92	—	unknown	20:20–01:00 (good, 4.67 h)	71.1° 19:55	9.72	45%	51.1°
2040-10-13 Sat	80	—	unknown	20:15–01:00 (good, 4.75 h)	71.1° 19:50	9.76	56%	47.7°
2040-10-14 Sun	57	—	unknown	20:15–00:10 (good, 3.92 h)	71.1° 19:50	9.8	68%	47.4°
2040-10-15 Mon	48	—	unknown	20:15–22:05 (good, 1.83 h)	71.1° 19:45	9.85	78%	50.2°
2040-10-16 Tue	44	—	unknown	20:10–20:50 (good, 0.67 h)	71.1° 19:40	9.89	87%	55.7°
2040-10-17 Wed	43	—	unknown	20:10–21:00 (good, 0.83 h)	71.1° 19:35	9.93	93%	63.1°
2040-10-18 Thu	47	—	unknown	20:10–21:40 (good, 1.5 h)	71.1° 19:30	9.98	98%	71.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-09-19&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.