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: 09-04 (15), 09-03 (12), 09-02 (9), 09-01 (6), 08-31 (4) — by astronomy; check the weather when the night is within four days.

2029-08-06astronomy score per night — click a bar for that night2029-09-04

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2029-08-06 Mon	0	—	unknown	—	42.9° 09:55	6.14	11%	30.9°
2029-08-07 Tue	0	—	unknown	—	42.9° 09:50	6.2	6%	36.6°
2029-08-08 Wed	0	—	unknown	—	42.9° 09:45	6.26	2%	45.4°
2029-08-09 Thu	0	—	unknown	—	42.9° 09:40	6.31	0%	56.0°
2029-08-10 Fri	0	—	unknown	—	42.9° 09:40	6.37	1%	67.7°
2029-08-11 Sat	0	—	unknown	—	42.9° 09:35	6.43	5%	80.0°
2029-08-12 Sun	0	—	unknown	—	42.9° 09:30	6.49	11%	92.6°
2029-08-13 Mon	0	—	unknown	—	42.9° 09:25	6.54	19%	105.1°
2029-08-14 Tue	0	—	unknown	—	42.9° 09:20	6.6	29%	117.4°
2029-08-15 Wed	0	—	unknown	—	42.9° 09:20	6.66	40%	128.9°
2029-08-16 Thu	0	—	unknown	—	42.9° 09:15	6.72	52%	139.1°
2029-08-17 Fri	0	—	unknown	—	42.9° 09:10	6.77	63%	146.9°
2029-08-18 Sat	0	—	unknown	—	42.9° 09:05	6.83	73%	150.5°
2029-08-19 Sun	1	—	unknown	—	42.9° 09:00	6.89	82%	148.5°
2029-08-20 Mon	1	—	unknown	—	42.9° 09:00	6.95	90%	142.1°
2029-08-21 Tue	1	—	unknown	—	42.9° 08:55	7.0	95%	133.3°
2029-08-22 Wed	1	—	unknown	—	42.9° 08:50	7.06	98%	123.2°
2029-08-23 Thu	1	—	unknown	—	42.9° 08:45	7.12	100%	112.7°
2029-08-24 Fri	1	—	unknown	—	42.9° 08:45	7.17	99%	102.0°
2029-08-25 Sat	2	—	unknown	04:55–05:05 (marginal, 0.17 h)	42.9° 08:40	7.23	96%	91.3°
2029-08-26 Sun	2	—	unknown	05:00–05:05 (marginal, 0.08 h)	42.9° 08:35	7.29	92%	80.8°
2029-08-27 Mon	2	—	unknown	05:00–05:05 (marginal, 0.08 h)	42.9° 08:30	7.35	86%	70.5°
2029-08-28 Tue	2	—	unknown	05:00–05:05 (marginal, 0.08 h)	42.9° 08:25	7.4	79%	60.5°
2029-08-29 Wed	2	—	unknown	05:00–05:10 (marginal, 0.17 h)	42.9° 08:25	7.46	71%	51.0°
2029-08-30 Thu	3	—	unknown	04:50–05:10 (marginal, 0.33 h)	42.9° 08:20	7.51	62%	42.3°
2029-08-31 Fri	4	—	unknown	04:40–05:10 (marginal, 0.5 h)	42.9° 08:15	7.57	52%	35.0°
2029-09-01 Sat	6	—	unknown	04:30–05:10 (marginal, 0.67 h)	42.9° 08:10	7.63	43%	30.3°
2029-09-02 Sun	9	—	unknown	04:20–05:15 (marginal, 0.92 h)	42.9° 08:05	7.68	33%	29.7°
2029-09-03 Mon	12	—	unknown	05:05–05:15 (good, 0.17 h)	42.9° 08:05	7.74	24%	33.8°
2029-09-04 Tue	15	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:00	7.79	16%	41.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2029-08-06&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.