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 Great Orion Nebula: 04-07 (1), 04-08 (1), 04-09 (1), 04-10 (1), 04-11 (1) — by astronomy; check the weather when the night is within four days.

2036-04-07astronomy score per night — click a bar for that night2036-05-06

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2036-04-07 Mon	1	—	unknown	—	42.9° 17:50	7.72	89%	79.9°
2036-04-08 Tue	1	—	unknown	—	42.9° 17:50	7.66	95%	92.8°
2036-04-09 Wed	1	—	unknown	—	42.9° 17:45	7.6	99%	105.6°
2036-04-10 Thu	1	—	unknown	—	42.9° 17:40	7.55	100%	118.0°
2036-04-11 Fri	1	—	unknown	—	42.9° 17:35	7.49	98%	129.8°
2036-04-12 Sat	1	—	unknown	—	42.9° 17:35	7.43	95%	140.5°
2036-04-13 Sun	1	—	unknown	—	42.9° 17:30	7.38	89%	149.4°
2036-04-14 Mon	0	—	unknown	—	42.9° 17:25	7.32	82%	154.9°
2036-04-15 Tue	0	—	unknown	—	42.9° 17:20	7.26	74%	155.2°
2036-04-16 Wed	0	—	unknown	—	42.9° 17:15	7.2	66%	150.4°
2036-04-17 Thu	0	—	unknown	—	42.9° 17:15	7.14	56%	142.6°
2036-04-18 Fri	0	—	unknown	—	42.9° 17:10	7.09	47%	133.2°
2036-04-19 Sat	0	—	unknown	—	42.9° 17:05	7.03	37%	123.1°
2036-04-20 Sun	0	—	unknown	—	42.9° 17:00	6.97	28%	112.5°
2036-04-21 Mon	0	—	unknown	—	42.9° 16:55	6.91	20%	101.6°
2036-04-22 Tue	0	—	unknown	—	42.9° 16:55	6.85	13%	90.3°
2036-04-23 Wed	0	—	unknown	—	42.9° 16:50	6.8	7%	78.8°
2036-04-24 Thu	0	—	unknown	—	42.9° 16:45	6.74	3%	67.0°
2036-04-25 Fri	0	—	unknown	—	42.9° 16:40	6.68	0%	55.3°
2036-04-26 Sat	0	—	unknown	—	42.9° 16:40	6.62	0%	43.9°
2036-04-27 Sun	0	—	unknown	—	42.9° 16:35	6.56	3%	33.5°
2036-04-28 Mon	0	—	unknown	—	42.9° 16:30	6.5	8%	26.1°
2036-04-29 Tue	0	—	unknown	—	42.9° 16:25	6.45	15%	24.7°
2036-04-30 Wed	0	—	unknown	—	42.9° 16:20	6.39	25%	30.3°
2036-05-01 Thu	0	—	unknown	—	42.9° 16:20	6.33	35%	40.1°
2036-05-02 Fri	0	—	unknown	—	42.9° 16:15	6.27	46%	51.7°
2036-05-03 Sat	0	—	unknown	—	42.9° 16:10	6.21	58%	64.0°
2036-05-04 Sun	0	—	unknown	—	42.9° 16:05	6.16	69%	76.6°
2036-05-05 Mon	0	—	unknown	—	42.9° 16:00	6.1	78%	89.3°
2036-05-06 Tue	0	—	unknown	—	42.9° 16:00	6.04	87%	101.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2036-04-07&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.