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: 09-01 (11), 09-02 (11), 09-03 (11), 08-31 (10), 09-04 (10) — by astronomy; check the weather when the night is within four days.

2047-08-11astronomy score per night — click a bar for that night2047-09-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2047-08-26 Mon	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.27	36%	132.9°
2047-08-27 Tue	5	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.33	48%	142.1°
2047-08-28 Wed	6	—	unknown	05:15–05:45 (marginal, 0.5 h)	42.9° 08:30	7.38	59%	148.2°
2047-08-29 Thu	8	—	unknown	04:40–05:45 (marginal, 1.08 h)	42.9° 08:25	7.44	70%	149.3°
2047-08-30 Fri	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.49	80%	145.1°
2047-08-31 Sat	10	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:15	7.55	88%	137.4°
2047-09-01 Sun	11	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.61	94%	127.8°
2047-09-02 Mon	11	—	unknown	05:05–05:15 (good, 0.17 h)	42.9° 08:10	7.66	98%	117.4°
2047-09-03 Tue	11	—	unknown	05:10–05:15 (good, 0.08 h)	42.9° 08:05	7.72	100%	106.6°
2047-09-04 Wed	10	—	unknown	04:15–05:15 (marginal, 1.0 h)	42.9° 08:00	7.77	100%	95.8°
2047-09-05 Thu	8	—	unknown	04:20–05:15 (marginal, 0.92 h)	42.9° 08:00	7.83	97%	85.1°
2047-09-06 Fri	8	—	unknown	04:25–05:20 (marginal, 0.92 h)	42.9° 07:55	7.88	93%	74.7°
2047-09-07 Sat	7	—	unknown	04:30–05:20 (marginal, 0.83 h)	42.9° 07:50	7.94	88%	64.5°
2047-09-08 Sun	6	—	unknown	04:30–05:20 (marginal, 0.83 h)	42.9° 07:45	7.99	81%	54.9°
2047-09-09 Mon	7	—	unknown	04:25–05:20 (marginal, 0.92 h)	42.9° 07:40	8.05	73%	46.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2047-08-11&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.