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: 09-01 (100), 09-02 (100), 09-03 (100), 09-04 (100), 09-16 (100) — by astronomy; check the weather when the night is within four days.

2030-09-01astronomy score per night — click a bar for that night2030-09-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-09-01 Sun	100	—	unknown	21:35–03:45 (good, 6.17 h)	71.1° 22:40	7.61	18%	98.4°
2030-09-02 Mon	100	—	unknown	21:35–03:40 (good, 6.08 h)	71.1° 22:35	7.67	28%	87.3°
2030-09-03 Tue	100	—	unknown	21:30–03:35 (good, 6.08 h)	71.1° 22:30	7.72	39%	76.2°
2030-09-04 Wed	100	—	unknown	21:30–03:35 (good, 6.08 h)	71.1° 22:25	7.78	50%	65.5°
2030-09-05 Thu	98	—	unknown	21:25–03:30 (good, 6.08 h)	71.1° 22:25	7.83	62%	55.5°
2030-09-06 Fri	89	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:20	7.89	72%	46.9°
2030-09-07 Sat	79	—	unknown	02:50–03:20 (good, 0.5 h)	71.1° 22:15	7.94	82%	40.7°
2030-09-08 Sun	40	—	unknown	21:20–03:35 (marginal, 6.25 h)	71.1° 22:10	8.0	90%	38.0°
2030-09-09 Mon	34	—	unknown	21:20–03:20 (marginal, 6.0 h)	71.1° 22:10	8.05	95%	39.4°
2030-09-10 Tue	35	—	unknown	21:15–03:05 (marginal, 5.83 h)	71.1° 22:05	8.11	99%	44.5°
2030-09-11 Wed	40	—	unknown	21:15–03:00 (marginal, 5.75 h)	71.1° 22:00	8.16	100%	52.0°
2030-09-12 Thu	50	—	unknown	21:15–21:45 (good, 0.5 h)	71.1° 21:55	8.21	99%	60.8°
2030-09-13 Fri	64	—	unknown	21:10–23:45 (good, 2.58 h)	71.1° 21:50	8.27	95%	70.3°
2030-09-14 Sat	78	—	unknown	21:10–00:55 (good, 3.75 h)	71.1° 21:50	8.32	90%	80.0°
2030-09-15 Sun	84	—	unknown	21:10–01:55 (good, 4.75 h)	71.1° 21:45	8.37	84%	89.6°
2030-09-16 Mon	100	—	unknown	21:05–02:25 (good, 5.33 h)	71.1° 21:40	8.43	76%	99.1°
2030-09-17 Tue	100	—	unknown	21:05–02:30 (good, 5.42 h)	71.1° 21:35	8.48	68%	108.4°
2030-09-18 Wed	100	—	unknown	21:00–02:30 (good, 5.5 h)	71.1° 21:30	8.53	58%	117.2°
2030-09-19 Thu	100	—	unknown	21:00–02:30 (good, 5.5 h)	71.1° 21:30	8.58	49%	125.4°
2030-09-20 Fri	100	—	unknown	21:00–02:25 (good, 5.42 h)	71.1° 21:25	8.63	40%	132.7°
2030-09-21 Sat	100	—	unknown	20:55–02:25 (good, 5.5 h)	71.1° 21:20	8.69	30%	138.4°
2030-09-22 Sun	100	—	unknown	20:55–02:25 (good, 5.5 h)	71.1° 21:15	8.74	22%	141.7°
2030-09-23 Mon	100	—	unknown	20:50–02:20 (good, 5.5 h)	71.1° 21:15	8.79	14%	141.7°
2030-09-24 Tue	100	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:10	8.84	8%	138.2°
2030-09-25 Wed	100	—	unknown	20:50–02:10 (good, 5.33 h)	71.1° 21:05	8.89	3%	131.6°
2030-09-26 Thu	100	—	unknown	20:45–02:05 (good, 5.33 h)	71.1° 21:00	8.94	0%	122.9°
2030-09-27 Fri	100	—	unknown	20:45–02:05 (good, 5.33 h)	71.1° 20:55	8.99	0%	112.8°
2030-09-28 Sat	100	—	unknown	20:45–02:00 (good, 5.25 h)	71.1° 20:55	9.04	3%	101.8°
2030-09-29 Sun	100	—	unknown	20:40–01:55 (good, 5.25 h)	71.1° 20:50	9.08	8%	90.5°
2030-09-30 Mon	100	—	unknown	20:40–01:50 (good, 5.17 h)	71.1° 20:45	9.13	16%	79.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-09-01&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.