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: 09-24 (52), 09-23 (50), 09-22 (48), 09-21 (47), 09-20 (45) — by astronomy; check the weather when the night is within four days.

2044-08-26astronomy score per night — click a bar for that night2044-09-24

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2044-09-03 Sat	16	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.76	88%	130.9°
2044-09-04 Sun	17	—	unknown	04:45–05:15 (good, 0.5 h)	42.9° 08:00	7.81	94%	122.2°
2044-09-05 Mon	17	—	unknown	04:55–05:20 (good, 0.42 h)	42.9° 07:55	7.87	98%	112.6°
2044-09-06 Tue	15	—	unknown	05:00–05:20 (good, 0.33 h)	42.9° 07:50	7.92	100%	102.5°
2044-09-07 Wed	13	—	unknown	05:15–05:20 (good, 0.08 h)	42.9° 07:45	7.98	100%	92.0°
2044-09-08 Thu	10	—	unknown	04:10–05:20 (marginal, 1.17 h)	42.9° 07:45	8.03	98%	81.2°
2044-09-09 Fri	9	—	unknown	04:15–05:25 (marginal, 1.17 h)	42.9° 07:40	8.09	94%	70.4°
2044-09-10 Sat	8	—	unknown	04:20–05:25 (marginal, 1.08 h)	42.9° 07:35	8.14	87%	59.9°
2044-09-11 Sun	7	—	unknown	04:15–05:25 (marginal, 1.17 h)	42.9° 07:30	8.19	79%	50.0°
2044-09-12 Mon	8	—	unknown	04:10–05:25 (marginal, 1.25 h)	42.9° 07:25	8.25	69%	41.4°
2044-09-13 Tue	11	—	unknown	03:55–05:30 (marginal, 1.58 h)	42.9° 07:25	8.3	58%	35.5°
2044-09-14 Wed	16	—	unknown	03:40–05:30 (marginal, 1.83 h)	42.9° 07:20	8.35	47%	33.9°
2044-09-15 Thu	22	—	unknown	04:30–05:30 (good, 1.0 h)	42.9° 07:15	8.41	36%	37.3°
2044-09-16 Fri	29	—	unknown	04:10–05:30 (good, 1.33 h)	42.9° 07:10	8.46	25%	44.6°
2044-09-17 Sat	35	—	unknown	04:00–05:35 (good, 1.58 h)	42.9° 07:10	8.51	16%	54.3°
2044-09-18 Sun	40	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 07:05	8.56	8%	65.2°
2044-09-19 Mon	43	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.61	3%	76.7°
2044-09-20 Tue	45	—	unknown	03:40–05:35 (good, 1.92 h)	42.9° 06:55	8.67	0%	88.4°
2044-09-21 Wed	47	—	unknown	03:40–05:40 (good, 2.0 h)	42.9° 06:50	8.72	0%	99.9°
2044-09-22 Thu	48	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.77	3%	111.0°
2044-09-23 Fri	50	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.82	7%	121.3°
2044-09-24 Sat	52	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:40	8.87	13%	130.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-08-26&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.