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: 08-31 (10), 08-30 (9), 09-02 (9), 08-29 (8), 09-01 (8) — by astronomy; check the weather when the night is within four days.

2039-08-04astronomy score per night — click a bar for that night2039-09-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-08-04 Thu	0	—	unknown	—	42.9° 10:05	6.01	100%	116.6°
2039-08-05 Fri	0	—	unknown	—	42.9° 10:00	6.06	97%	104.5°
2039-08-06 Sat	0	—	unknown	—	42.9° 09:55	6.12	92%	92.6°
2039-08-07 Sun	0	—	unknown	—	42.9° 09:50	6.18	85%	80.9°
2039-08-08 Mon	0	—	unknown	—	42.9° 09:50	6.23	77%	69.7°
2039-08-09 Tue	0	—	unknown	—	42.9° 09:45	6.29	68%	59.1°
2039-08-10 Wed	0	—	unknown	—	42.9° 09:40	6.35	58%	49.3°
2039-08-11 Thu	0	—	unknown	—	42.9° 09:35	6.4	49%	40.6°
2039-08-12 Fri	0	—	unknown	—	42.9° 09:30	6.46	40%	33.5°
2039-08-13 Sat	0	—	unknown	—	42.9° 09:30	6.52	30%	29.4°
2039-08-14 Sun	0	—	unknown	—	42.9° 09:25	6.58	22%	29.3°
2039-08-15 Mon	0	—	unknown	—	42.9° 09:20	6.63	15%	33.4°
2039-08-16 Tue	0	—	unknown	—	42.9° 09:15	6.69	9%	40.5°
2039-08-17 Wed	0	—	unknown	—	42.9° 09:10	6.75	4%	49.5°
2039-08-18 Thu	0	—	unknown	—	42.9° 09:10	6.81	1%	59.5°
2039-08-19 Fri	0	—	unknown	—	42.9° 09:05	6.86	0%	70.4°
2039-08-20 Sat	1	—	unknown	—	42.9° 09:00	6.92	1%	81.7°
2039-08-21 Sun	1	—	unknown	—	42.9° 08:55	6.98	5%	93.3°
2039-08-22 Mon	1	—	unknown	—	42.9° 08:55	7.04	11%	105.0°
2039-08-23 Tue	1	—	unknown	—	42.9° 08:50	7.09	18%	116.7°
2039-08-24 Wed	2	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:45	7.15	28%	128.0°
2039-08-25 Thu	3	—	unknown	05:25–05:40 (marginal, 0.25 h)	42.9° 08:40	7.21	38%	138.4°
2039-08-26 Fri	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.26	50%	146.7°
2039-08-27 Sat	5	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.32	61%	150.9°
2039-08-28 Sun	6	—	unknown	05:15–05:45 (marginal, 0.5 h)	42.9° 08:30	7.38	72%	149.2°
2039-08-29 Mon	8	—	unknown	04:40–05:45 (marginal, 1.08 h)	42.9° 08:25	7.43	82%	142.2°
2039-08-30 Tue	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.49	90%	132.3°
2039-08-31 Wed	10	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:15	7.55	95%	121.0°
2039-09-01 Thu	8	—	unknown	04:30–05:10 (marginal, 0.67 h)	42.9° 08:15	7.6	99%	109.2°
2039-09-02 Fri	9	—	unknown	04:25–05:15 (marginal, 0.83 h)	42.9° 08:10	7.66	100%	97.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-08-04&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.