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: 09-05 (21), 09-04 (17), 09-03 (16), 09-02 (15), 09-01 (12) — by astronomy; check the weather when the night is within four days.

2033-08-07astronomy score per night — click a bar for that night2033-09-05

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2033-08-07 Sun	0	—	unknown	—	42.9° 09:50	6.2	90%	152.2°
2033-08-08 Mon	0	—	unknown	—	42.9° 09:45	6.26	95%	143.5°
2033-08-09 Tue	0	—	unknown	—	42.9° 09:40	6.32	99%	132.3°
2033-08-10 Wed	0	—	unknown	—	42.9° 09:40	6.37	100%	119.8°
2033-08-11 Thu	0	—	unknown	—	42.9° 09:35	6.43	98%	106.6°
2033-08-12 Fri	0	—	unknown	—	42.9° 09:30	6.49	93%	93.2°
2033-08-13 Sat	0	—	unknown	—	42.9° 09:25	6.54	86%	79.7°
2033-08-14 Sun	0	—	unknown	—	42.9° 09:20	6.6	77%	66.4°
2033-08-15 Mon	0	—	unknown	—	42.9° 09:20	6.66	66%	53.7°
2033-08-16 Tue	0	—	unknown	—	42.9° 09:15	6.72	55%	41.9°
2033-08-17 Wed	0	—	unknown	—	42.9° 09:10	6.78	44%	31.8°
2033-08-18 Thu	0	—	unknown	—	42.9° 09:05	6.83	34%	25.1°
2033-08-19 Fri	0	—	unknown	—	42.9° 09:00	6.89	24%	24.4°
2033-08-20 Sat	1	—	unknown	—	42.9° 09:00	6.95	16%	29.7°
2033-08-21 Sun	1	—	unknown	—	42.9° 08:55	7.0	9%	38.5°
2033-08-22 Mon	1	—	unknown	—	42.9° 08:50	7.06	4%	48.6°
2033-08-23 Tue	2	—	unknown	—	42.9° 08:45	7.12	1%	59.4°
2033-08-24 Wed	2	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:45	7.18	0%	70.4°
2033-08-25 Thu	4	—	unknown	05:25–05:40 (marginal, 0.25 h)	42.9° 08:40	7.23	1%	81.4°
2033-08-26 Fri	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.29	4%	92.3°
2033-08-27 Sat	5	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.35	8%	103.2°
2033-08-28 Sun	7	—	unknown	04:40–05:05 (marginal, 0.42 h)	42.9° 08:25	7.4	14%	113.9°
2033-08-29 Mon	8	—	unknown	04:40–05:45 (marginal, 1.08 h)	42.9° 08:25	7.46	21%	124.4°
2033-08-30 Tue	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.52	30%	134.5°
2033-08-31 Wed	10	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.57	39%	143.9°
2033-09-01 Thu	12	—	unknown	04:55–05:10 (good, 0.25 h)	42.9° 08:10	7.63	48%	151.7°
2033-09-02 Fri	15	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:05	7.68	58%	156.0°
2033-09-03 Sat	16	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.74	68%	154.5°
2033-09-04 Sun	17	—	unknown	04:45–05:15 (good, 0.5 h)	42.9° 08:00	7.79	78%	147.6°
2033-09-05 Mon	21	—	unknown	04:40–05:20 (good, 0.67 h)	42.9° 07:55	7.85	86%	137.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2033-08-07&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.