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: 08-23 (2), 08-24 (2), 08-25 (2), 08-19 (1), 08-20 (1) — by astronomy; check the weather when the night is within four days.

2037-07-27astronomy score per night — click a bar for that night2037-08-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-07-27 Mon	0	—	unknown	—	42.9° 10:35	5.6	99%	122.9°
2037-07-28 Tue	0	—	unknown	—	42.9° 10:30	5.65	97%	112.3°
2037-07-29 Wed	0	—	unknown	—	42.9° 10:25	5.7	93%	101.6°
2037-07-30 Thu	0	—	unknown	—	42.9° 10:20	5.76	87%	90.9°
2037-07-31 Fri	0	—	unknown	—	42.9° 10:15	5.81	80%	80.2°
2037-08-01 Sat	0	—	unknown	—	42.9° 10:15	5.87	72%	69.6°
2037-08-02 Sun	0	—	unknown	—	42.9° 10:10	5.92	63%	59.2°
2037-08-03 Mon	0	—	unknown	—	42.9° 10:05	5.98	54%	49.0°
2037-08-04 Tue	0	—	unknown	—	42.9° 10:00	6.03	44%	39.4°
2037-08-05 Wed	0	—	unknown	—	42.9° 10:00	6.09	34%	31.1°
2037-08-06 Thu	0	—	unknown	—	42.9° 09:55	6.15	25%	26.0°
2037-08-07 Fri	0	—	unknown	—	42.9° 09:50	6.2	16%	26.6°
2037-08-08 Sat	0	—	unknown	—	42.9° 09:45	6.26	9%	33.0°
2037-08-09 Sun	0	—	unknown	—	42.9° 09:40	6.32	3%	43.2°
2037-08-10 Mon	0	—	unknown	—	42.9° 09:40	6.37	0%	55.2°
2037-08-11 Tue	0	—	unknown	—	42.9° 09:35	6.43	0%	68.2°
2037-08-12 Wed	0	—	unknown	—	42.9° 09:30	6.49	3%	81.6°
2037-08-13 Thu	0	—	unknown	—	42.9° 09:25	6.55	9%	95.1°
2037-08-14 Fri	0	—	unknown	—	42.9° 09:20	6.6	17%	108.4°
2037-08-15 Sat	0	—	unknown	—	42.9° 09:20	6.66	27%	121.2°
2037-08-16 Sun	0	—	unknown	—	42.9° 09:15	6.72	38%	133.1°
2037-08-17 Mon	0	—	unknown	—	42.9° 09:10	6.78	49%	143.6°
2037-08-18 Tue	0	—	unknown	—	42.9° 09:05	6.83	60%	151.3°
2037-08-19 Wed	1	—	unknown	—	42.9° 09:00	6.89	70%	154.5°
2037-08-20 Thu	1	—	unknown	—	42.9° 09:00	6.95	79%	151.8°
2037-08-21 Fri	1	—	unknown	—	42.9° 08:55	7.01	86%	144.8°
2037-08-22 Sat	1	—	unknown	—	42.9° 08:50	7.06	92%	135.7°
2037-08-23 Sun	2	—	unknown	—	42.9° 08:45	7.12	97%	125.7°
2037-08-24 Mon	2	—	unknown	—	42.9° 08:45	7.18	99%	115.2°
2037-08-25 Tue	2	—	unknown	04:55–05:05 (marginal, 0.17 h)	42.9° 08:40	7.24	100%	104.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-07-27&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.