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: 09-30 (100), 10-01 (100), 10-02 (100), 10-03 (100), 10-04 (100) — by astronomy; check the weather when the night is within four days.

2045-09-20astronomy score per night — click a bar for that night2045-10-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-09-20 Wed	75	—	unknown	20:55–01:25 (good, 4.5 h)	71.1° 21:25	8.65	76%	44.8°
2045-09-21 Thu	48	—	unknown	20:55–02:50 (marginal, 5.92 h)	71.1° 21:20	8.7	84%	43.2°
2045-09-22 Fri	41	—	unknown	20:55–02:35 (marginal, 5.67 h)	71.1° 21:15	8.75	90%	44.2°
2045-09-23 Sat	38	—	unknown	20:50–02:25 (marginal, 5.58 h)	71.1° 21:10	8.81	95%	47.5°
2045-09-24 Sun	38	—	unknown	20:50–02:15 (marginal, 5.42 h)	71.1° 21:10	8.86	98%	52.9°
2045-09-25 Mon	42	—	unknown	20:50–02:10 (marginal, 5.33 h)	71.1° 21:05	8.91	100%	59.7°
2045-09-26 Tue	51	—	unknown	20:45–21:55 (good, 1.17 h)	71.1° 21:00	8.96	100%	67.6°
2045-09-27 Wed	62	—	unknown	20:45–23:20 (good, 2.58 h)	71.1° 20:55	9.0	97%	76.2°
2045-09-28 Thu	75	—	unknown	20:45–00:15 (good, 3.5 h)	71.1° 20:50	9.05	93%	85.2°
2045-09-29 Fri	84	—	unknown	20:40–01:15 (good, 4.58 h)	71.1° 20:50	9.1	87%	94.5°
2045-09-30 Sat	100	—	unknown	20:40–01:30 (good, 4.83 h)	71.1° 20:45	9.15	79%	103.9°
2045-10-01 Sun	100	—	unknown	20:35–01:35 (good, 5.0 h)	71.1° 20:40	9.2	70%	113.0°
2045-10-02 Mon	100	—	unknown	20:35–01:35 (good, 5.0 h)	71.1° 20:35	9.25	59%	121.6°
2045-10-03 Tue	100	—	unknown	20:35–01:35 (good, 5.0 h)	71.1° 20:30	9.29	48%	129.0°
2045-10-04 Wed	100	—	unknown	20:30–01:30 (good, 5.0 h)	71.1° 20:30	9.34	37%	134.4°
2045-10-05 Thu	100	—	unknown	20:30–01:30 (good, 5.0 h)	71.1° 20:25	9.39	26%	136.8°
2045-10-06 Fri	100	—	unknown	20:30–01:25 (good, 4.92 h)	71.1° 20:20	9.43	17%	135.5°
2045-10-07 Sat	100	—	unknown	20:25–01:25 (good, 5.0 h)	71.1° 20:15	9.48	9%	130.5°
2045-10-08 Sun	100	—	unknown	20:25–01:20 (good, 4.92 h)	71.1° 20:15	9.53	3%	122.9°
2045-10-09 Mon	100	—	unknown	20:25–01:15 (good, 4.83 h)	71.1° 20:10	9.57	0%	113.7°
2045-10-10 Tue	100	—	unknown	20:20–01:10 (good, 4.83 h)	71.1° 20:05	9.62	0%	103.6°
2045-10-11 Wed	100	—	unknown	20:20–01:05 (good, 4.75 h)	71.1° 20:00	9.66	3%	93.3°
2045-10-12 Thu	100	—	unknown	20:20–01:05 (good, 4.75 h)	71.1° 19:55	9.71	8%	83.2°
2045-10-13 Fri	100	—	unknown	20:15–01:00 (good, 4.75 h)	71.1° 19:55	9.75	15%	73.5°
2045-10-14 Sat	100	—	unknown	20:15–00:55 (good, 4.67 h)	71.1° 19:50	9.79	23%	64.6°
2045-10-15 Sun	99	—	unknown	20:15–00:50 (good, 4.58 h)	71.1° 19:45	9.84	32%	56.8°
2045-10-16 Mon	91	—	unknown	20:15–00:50 (good, 4.58 h)	71.1° 19:40	9.88	42%	50.3°
2045-10-17 Tue	79	—	unknown	20:10–00:45 (good, 4.58 h)	71.1° 19:35	9.92	51%	45.6°
2045-10-18 Wed	58	—	unknown	20:10–00:15 (good, 4.08 h)	71.1° 19:35	9.97	61%	43.2°
2045-10-19 Thu	47	—	unknown	20:10–22:10 (good, 2.0 h)	71.1° 19:30	10.01	70%	43.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-09-20&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.