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.

2033-04-20astronomy score per night — click a bar for that night2033-05-19

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2033-04-20 Wed	—	unknown	—	42.9° 17:00	6.99	67%	150.6°
2033-04-21 Thu	—	unknown	—	42.9° 17:00	6.93	56%	141.7°
2033-04-22 Fri	—	unknown	—	42.9° 16:55	6.87	45%	130.7°
2033-04-23 Sat	—	unknown	—	42.9° 16:50	6.81	34%	118.6°
2033-04-24 Sun	—	unknown	—	42.9° 16:45	6.75	24%	105.7°
2033-04-25 Mon	—	unknown	—	42.9° 16:40	6.69	14%	92.3°
2033-04-26 Tue	—	unknown	—	42.9° 16:40	6.64	7%	78.8°
2033-04-27 Wed	—	unknown	—	42.9° 16:35	6.58	2%	65.2°
2033-04-28 Thu	—	unknown	—	42.9° 16:30	6.52	0%	52.1°
2033-04-29 Fri	—	unknown	—	42.9° 16:25	6.46	1%	40.0°
2033-04-30 Sat	—	unknown	—	42.9° 16:25	6.4	5%	30.0°
2033-05-01 Sun	—	unknown	—	42.9° 16:20	6.35	11%	24.4°
2033-05-02 Mon	—	unknown	—	42.9° 16:15	6.29	18%	25.6°
2033-05-03 Tue	—	unknown	—	42.9° 16:10	6.23	27%	32.3°
2033-05-04 Wed	—	unknown	—	42.9° 16:05	6.17	37%	41.6°
2033-05-05 Thu	—	unknown	—	42.9° 16:05	6.12	46%	51.9°
2033-05-06 Fri	—	unknown	—	42.9° 16:00	6.06	56%	62.5°
2033-05-07 Sat	—	unknown	—	42.9° 15:55	6.0	66%	73.2°
2033-05-08 Sun	—	unknown	—	42.9° 15:50	5.95	74%	84.0°
2033-05-09 Mon	—	unknown	—	42.9° 15:45	5.89	82%	94.8°
2033-05-10 Tue	—	unknown	—	42.9° 15:45	5.83	89%	105.6°
2033-05-11 Wed	—	unknown	—	42.9° 15:40	5.78	94%	116.4°
2033-05-12 Thu	—	unknown	—	42.9° 15:35	5.72	98%	127.0°
2033-05-13 Fri	—	unknown	—	42.9° 15:30	5.67	100%	137.2°
2033-05-14 Sat	—	unknown	—	42.9° 15:30	5.62	100%	146.5°
2033-05-15 Sun	—	unknown	—	42.9° 15:25	5.56	98%	153.5°
2033-05-16 Mon	—	unknown	—	42.9° 15:20	5.51	94%	155.9°
2033-05-17 Tue	—	unknown	—	42.9° 15:15	5.46	87%	152.1°
2033-05-18 Wed	—	unknown	—	42.9° 15:10	5.41	80%	143.9°
2033-05-19 Thu	—	unknown	—	42.9° 15:10	5.35	70%	133.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2033-04-20&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.