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 (15), 09-01 (13), 08-31 (10), 08-29 (9), 08-30 (9) — by astronomy; check the weather when the night is within four days.

2044-08-04astronomy score per night — click a bar for that night2044-09-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-08-04 Thu	0	—	unknown	—	42.9° 10:00	6.05	86%	145.8°
2044-08-05 Fri	0	—	unknown	—	42.9° 09:55	6.11	92%	142.3°
2044-08-06 Sat	0	—	unknown	—	42.9° 09:55	6.16	96%	136.2°
2044-08-07 Sun	0	—	unknown	—	42.9° 09:50	6.22	99%	128.4°
2044-08-08 Mon	0	—	unknown	—	42.9° 09:45	6.28	100%	119.4°
2044-08-09 Tue	0	—	unknown	—	42.9° 09:40	6.33	99%	109.7°
2044-08-10 Wed	0	—	unknown	—	42.9° 09:35	6.39	96%	99.5°
2044-08-11 Thu	0	—	unknown	—	42.9° 09:35	6.45	91%	89.1°
2044-08-12 Fri	0	—	unknown	—	42.9° 09:30	6.51	84%	78.4°
2044-08-13 Sat	0	—	unknown	—	42.9° 09:25	6.56	76%	67.8°
2044-08-14 Sun	0	—	unknown	—	42.9° 09:20	6.62	66%	57.5°
2044-08-15 Mon	0	—	unknown	—	42.9° 09:15	6.68	55%	47.8°
2044-08-16 Tue	0	—	unknown	—	42.9° 09:15	6.74	44%	39.7°
2044-08-17 Wed	0	—	unknown	—	42.9° 09:10	6.79	33%	34.7°
2044-08-18 Thu	0	—	unknown	—	42.9° 09:05	6.85	22%	34.3°
2044-08-19 Fri	1	—	unknown	—	42.9° 09:00	6.91	13%	39.1°
2044-08-20 Sat	1	—	unknown	—	42.9° 09:00	6.97	6%	47.6°
2044-08-21 Sun	1	—	unknown	—	42.9° 08:55	7.02	2%	58.1°
2044-08-22 Mon	1	—	unknown	—	42.9° 08:50	7.08	0%	69.6°
2044-08-23 Tue	2	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:45	7.14	1%	81.4°
2044-08-24 Wed	3	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:40	7.2	5%	93.2°
2044-08-25 Thu	4	—	unknown	05:25–05:40 (marginal, 0.25 h)	42.9° 08:40	7.25	10%	104.5°
2044-08-26 Fri	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.31	18%	115.2°
2044-08-27 Sat	5	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.37	27%	125.0°
2044-08-28 Sun	7	—	unknown	05:10–05:45 (marginal, 0.58 h)	42.9° 08:25	7.42	36%	133.7°
2044-08-29 Mon	9	—	unknown	04:35–05:45 (marginal, 1.17 h)	42.9° 08:20	7.48	46%	140.6°
2044-08-30 Tue	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.54	55%	145.0°
2044-08-31 Wed	10	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.59	64%	146.1°
2044-09-01 Thu	13	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:10	7.65	73%	143.6°
2044-09-02 Fri	15	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.7	81%	138.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-08-04&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.