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: 08-25 (3), 08-24 (2), 08-20 (1), 08-21 (1), 08-22 (1) — by astronomy; check the weather when the night is within four days.

2047-07-27astronomy score per night — click a bar for that night2047-08-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2047-07-27 Sat	0	—	unknown	—	42.9° 10:35	5.57	28%	101.0°
2047-07-28 Sun	0	—	unknown	—	42.9° 10:30	5.63	39%	113.0°
2047-07-29 Mon	0	—	unknown	—	42.9° 10:25	5.68	50%	124.5°
2047-07-30 Tue	0	—	unknown	—	42.9° 10:25	5.73	62%	135.1°
2047-07-31 Wed	0	—	unknown	—	42.9° 10:20	5.79	72%	143.7°
2047-08-01 Thu	0	—	unknown	—	42.9° 10:15	5.84	82%	148.8°
2047-08-02 Fri	0	—	unknown	—	42.9° 10:10	5.9	90%	148.5°
2047-08-03 Sat	0	—	unknown	—	42.9° 10:10	5.95	96%	143.2°
2047-08-04 Sun	0	—	unknown	—	42.9° 10:05	6.01	99%	134.6°
2047-08-05 Mon	0	—	unknown	—	42.9° 10:00	6.07	100%	124.6°
2047-08-06 Tue	0	—	unknown	—	42.9° 09:55	6.12	99%	113.9°
2047-08-07 Wed	0	—	unknown	—	42.9° 09:50	6.18	95%	103.0°
2047-08-08 Thu	0	—	unknown	—	42.9° 09:50	6.24	90%	92.2°
2047-08-09 Fri	0	—	unknown	—	42.9° 09:45	6.29	83%	81.6°
2047-08-10 Sat	0	—	unknown	—	42.9° 09:40	6.35	75%	71.3°
2047-08-11 Sun	0	—	unknown	—	42.9° 09:35	6.41	67%	61.4°
2047-08-12 Mon	0	—	unknown	—	42.9° 09:30	6.47	57%	52.0°
2047-08-13 Tue	0	—	unknown	—	42.9° 09:30	6.52	48%	43.4°
2047-08-14 Wed	0	—	unknown	—	42.9° 09:25	6.58	39%	36.3°
2047-08-15 Thu	0	—	unknown	—	42.9° 09:20	6.64	30%	31.6°
2047-08-16 Fri	0	—	unknown	—	42.9° 09:15	6.7	21%	30.8°
2047-08-17 Sat	0	—	unknown	—	42.9° 09:10	6.75	13%	34.3°
2047-08-18 Sun	0	—	unknown	—	42.9° 09:10	6.81	7%	41.4°
2047-08-19 Mon	0	—	unknown	—	42.9° 09:05	6.87	3%	50.7°
2047-08-20 Tue	1	—	unknown	—	42.9° 09:00	6.93	0%	61.5°
2047-08-21 Wed	1	—	unknown	—	42.9° 08:55	6.98	0%	73.2°
2047-08-22 Thu	1	—	unknown	—	42.9° 08:55	7.04	3%	85.3°
2047-08-23 Fri	1	—	unknown	—	42.9° 08:50	7.1	9%	97.7°
2047-08-24 Sat	2	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:45	7.15	16%	110.0°
2047-08-25 Sun	3	—	unknown	05:25–05:40 (marginal, 0.25 h)	42.9° 08:40	7.21	26%	121.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2047-07-27&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.