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: 09-02 (14), 09-01 (12), 08-31 (10), 08-30 (9), 08-29 (8) — by astronomy; check the weather when the night is within four days.

2038-08-04astronomy score per night — click a bar for that night2038-09-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-08-04 Wed	0	—	unknown	—	42.9° 10:00	6.02	19%	102.0°
2038-08-05 Thu	0	—	unknown	—	42.9° 10:00	6.08	29%	114.5°
2038-08-06 Fri	0	—	unknown	—	42.9° 09:55	6.13	40%	126.6°
2038-08-07 Sat	0	—	unknown	—	42.9° 09:50	6.19	51%	137.7°
2038-08-08 Sun	0	—	unknown	—	42.9° 09:45	6.25	62%	147.0°
2038-08-09 Mon	0	—	unknown	—	42.9° 09:45	6.3	73%	152.4°
2038-08-10 Tue	0	—	unknown	—	42.9° 09:40	6.36	82%	151.8°
2038-08-11 Wed	0	—	unknown	—	42.9° 09:35	6.42	90%	145.8°
2038-08-12 Thu	0	—	unknown	—	42.9° 09:30	6.47	95%	136.6°
2038-08-13 Fri	0	—	unknown	—	42.9° 09:25	6.53	99%	126.1°
2038-08-14 Sat	0	—	unknown	—	42.9° 09:25	6.59	100%	115.0°
2038-08-15 Sun	0	—	unknown	—	42.9° 09:20	6.65	99%	103.8°
2038-08-16 Mon	0	—	unknown	—	42.9° 09:15	6.7	96%	92.6°
2038-08-17 Tue	0	—	unknown	—	42.9° 09:10	6.76	91%	81.6°
2038-08-18 Wed	0	—	unknown	—	42.9° 09:05	6.82	85%	70.9°
2038-08-19 Thu	0	—	unknown	—	42.9° 09:05	6.88	77%	60.6°
2038-08-20 Fri	0	—	unknown	—	42.9° 09:00	6.94	69%	50.7°
2038-08-21 Sat	0	—	unknown	—	42.9° 08:55	6.99	60%	41.6°
2038-08-22 Sun	1	—	unknown	—	42.9° 08:50	7.05	50%	33.8°
2038-08-23 Mon	1	—	unknown	—	42.9° 08:50	7.11	41%	28.5°
2038-08-24 Tue	1	—	unknown	—	42.9° 08:45	7.16	31%	27.3°
2038-08-25 Wed	2	—	unknown	04:55–05:00 (marginal, 0.08 h)	42.9° 08:40	7.22	22%	31.1°
2038-08-26 Thu	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.28	14%	38.7°
2038-08-27 Fri	5	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.33	8%	48.6°
2038-08-28 Sat	6	—	unknown	05:15–05:45 (marginal, 0.5 h)	42.9° 08:30	7.39	3%	59.9°
2038-08-29 Sun	8	—	unknown	04:40–05:45 (marginal, 1.08 h)	42.9° 08:25	7.45	0%	72.1°
2038-08-30 Mon	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.5	0%	84.8°
2038-08-31 Tue	10	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.56	3%	97.7°
2038-09-01 Wed	12	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:10	7.62	9%	110.7°
2038-09-02 Thu	14	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:10	7.67	17%	123.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-08-04&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.