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: 08-29 (8), 08-30 (8), 08-31 (7), 08-28 (6), 09-01 (6) — by astronomy; check the weather when the night is within four days.

2031-08-06astronomy score per night — click a bar for that night2031-09-04

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-08-06 Wed	0	—	unknown	—	42.9° 09:55	6.12	80%	79.6°
2031-08-07 Thu	0	—	unknown	—	42.9° 09:50	6.17	71%	67.6°
2031-08-08 Fri	0	—	unknown	—	42.9° 09:50	6.23	61%	56.3°
2031-08-09 Sat	0	—	unknown	—	42.9° 09:45	6.29	51%	45.8°
2031-08-10 Sun	0	—	unknown	—	42.9° 09:40	6.34	41%	36.7°
2031-08-11 Mon	0	—	unknown	—	42.9° 09:35	6.4	32%	29.7°
2031-08-12 Tue	0	—	unknown	—	42.9° 09:30	6.46	23%	26.3°
2031-08-13 Wed	0	—	unknown	—	42.9° 09:30	6.52	16%	27.6°
2031-08-14 Thu	0	—	unknown	—	42.9° 09:25	6.57	10%	33.1°
2031-08-15 Fri	0	—	unknown	—	42.9° 09:20	6.63	5%	41.0°
2031-08-16 Sat	0	—	unknown	—	42.9° 09:15	6.69	2%	50.4°
2031-08-17 Sun	0	—	unknown	—	42.9° 09:10	6.75	0%	60.5°
2031-08-18 Mon	0	—	unknown	—	42.9° 09:10	6.8	1%	71.1°
2031-08-19 Tue	0	—	unknown	—	42.9° 09:05	6.86	3%	82.1°
2031-08-20 Wed	1	—	unknown	—	42.9° 09:00	6.92	7%	93.3°
2031-08-21 Thu	1	—	unknown	—	42.9° 08:55	6.98	14%	104.6°
2031-08-22 Fri	1	—	unknown	—	42.9° 08:55	7.03	21%	116.0°
2031-08-23 Sat	1	—	unknown	—	42.9° 08:50	7.09	30%	127.2°
2031-08-24 Sun	2	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:45	7.15	41%	137.9°
2031-08-25 Mon	3	—	unknown	05:25–05:40 (marginal, 0.25 h)	42.9° 08:40	7.2	52%	147.2°
2031-08-26 Tue	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.26	63%	153.2°
2031-08-27 Wed	5	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.32	74%	152.9°
2031-08-28 Thu	6	—	unknown	05:15–05:45 (marginal, 0.5 h)	42.9° 08:30	7.37	83%	146.3°
2031-08-29 Fri	8	—	unknown	04:40–05:45 (marginal, 1.08 h)	42.9° 08:25	7.43	91%	135.8°
2031-08-30 Sat	8	—	unknown	04:35–05:10 (marginal, 0.58 h)	42.9° 08:20	7.49	97%	123.7°
2031-08-31 Sun	7	—	unknown	04:30–05:10 (marginal, 0.67 h)	42.9° 08:15	7.54	100%	110.8°
2031-09-01 Mon	6	—	unknown	04:30–05:10 (marginal, 0.67 h)	42.9° 08:15	7.6	99%	97.7°
2031-09-02 Tue	6	—	unknown	04:30–05:15 (marginal, 0.75 h)	42.9° 08:10	7.66	97%	84.8°
2031-09-03 Wed	5	—	unknown	04:35–05:15 (marginal, 0.67 h)	42.9° 08:05	7.71	92%	72.3°
2031-09-04 Thu	5	—	unknown	04:40–05:15 (marginal, 0.58 h)	42.9° 08:00	7.77	84%	60.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-08-06&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.