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 Vega: 08-25 (100), 08-26 (100), 08-27 (100), 08-28 (100), 08-29 (100) — by astronomy; check the weather when the night is within four days.

2040-08-20astronomy score per night — click a bar for that night2040-09-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-08-20 Mon	67	—	unknown	22:00–01:50 (good, 3.83 h)	87.1° 22:00	6.96	97%	68.7°
2040-08-21 Tue	69	—	unknown	21:55–01:20 (good, 3.42 h)	87.1° 21:55	7.02	100%	72.8°
2040-08-22 Wed	73	—	unknown	21:55–01:30 (good, 3.58 h)	87.1° 21:55	7.08	99%	77.9°
2040-08-23 Thu	78	—	unknown	21:50–01:55 (good, 4.08 h)	87.1° 21:50	7.14	96%	83.7°
2040-08-24 Fri	83	—	unknown	21:50–02:35 (good, 4.75 h)	87.1° 21:45	7.19	91%	89.7°
2040-08-25 Sat	100	—	unknown	21:50–03:10 (good, 5.33 h)	87.1° 21:40	7.25	84%	95.5°
2040-08-26 Sun	100	—	unknown	21:45–03:15 (good, 5.5 h)	87.1° 21:35	7.31	75%	100.8°
2040-08-27 Mon	100	—	unknown	21:45–03:15 (good, 5.5 h)	87.1° 21:35	7.36	65%	105.5°
2040-08-28 Tue	100	—	unknown	21:40–03:15 (good, 5.58 h)	87.1° 21:30	7.42	55%	109.3°
2040-08-29 Wed	100	—	unknown	21:40–03:15 (good, 5.58 h)	87.1° 21:25	7.48	46%	112.2°
2040-08-30 Thu	100	—	unknown	21:40–03:15 (good, 5.58 h)	87.1° 21:20	7.53	36%	114.1°
2040-08-31 Fri	100	—	unknown	21:35–03:15 (good, 5.67 h)	87.1° 21:15	7.59	27%	114.8°
2040-09-01 Sat	100	—	unknown	21:35–03:10 (good, 5.58 h)	87.1° 21:15	7.65	19%	114.4°
2040-09-02 Sun	100	—	unknown	21:30–03:10 (good, 5.67 h)	87.1° 21:10	7.7	12%	112.9°
2040-09-03 Mon	100	—	unknown	21:30–03:05 (good, 5.58 h)	87.1° 21:05	7.76	7%	110.4°
2040-09-04 Tue	100	—	unknown	21:30–03:00 (good, 5.5 h)	87.1° 21:00	7.81	3%	107.0°
2040-09-05 Wed	100	—	unknown	21:25–02:55 (good, 5.5 h)	87.1° 21:00	7.87	1%	102.9°
2040-09-06 Thu	100	—	unknown	21:25–02:55 (good, 5.5 h)	87.1° 20:55	7.92	0%	98.2°
2040-09-07 Fri	100	—	unknown	21:20–02:50 (good, 5.5 h)	87.1° 20:50	7.98	2%	93.1°
2040-09-08 Sat	100	—	unknown	21:20–02:45 (good, 5.42 h)	87.1° 20:45	8.03	5%	87.8°
2040-09-09 Sun	100	—	unknown	21:20–02:40 (good, 5.33 h)	87.1° 20:40	8.08	11%	82.6°
2040-09-10 Mon	100	—	unknown	21:15–02:35 (good, 5.33 h)	87.1° 20:40	8.14	18%	77.5°
2040-09-11 Tue	100	—	unknown	21:15–02:35 (good, 5.33 h)	87.1° 20:35	8.19	27%	73.0°
2040-09-12 Wed	100	—	unknown	21:10–02:30 (good, 5.33 h)	87.1° 20:30	8.25	37%	69.3°
2040-09-13 Thu	99	—	unknown	21:10–02:25 (good, 5.25 h)	87.1° 20:25	8.3	48%	66.7°
2040-09-14 Fri	91	—	unknown	21:10–02:20 (good, 5.17 h)	87.1° 20:20	8.35	60%	65.4°
2040-09-15 Sat	84	—	unknown	21:05–02:20 (good, 5.25 h)	87.1° 20:20	8.4	70%	65.7°
2040-09-16 Sun	69	—	unknown	21:05–01:45 (good, 4.67 h)	87.1° 20:15	8.46	80%	67.7°
2040-09-17 Mon	62	—	unknown	21:05–00:35 (good, 3.5 h)	87.1° 20:10	8.51	89%	71.1°
2040-09-18 Tue	62	—	unknown	21:00–23:55 (good, 2.92 h)	87.1° 20:05	8.56	95%	75.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-08-20&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.