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: 09-30 (63), 09-29 (60), 09-28 (59), 09-27 (57), 09-26 (56) — by astronomy; check the weather when the night is within four days.

2044-09-01astronomy score per night — click a bar for that night2044-09-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2044-09-25 Sun	55	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:35	8.92	21%	138.4°
2044-09-26 Mon	56	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:30	8.97	29%	143.9°
2044-09-27 Tue	57	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:30	9.02	38%	146.2°
2044-09-28 Wed	59	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.07	48%	144.9°
2044-09-29 Thu	60	—	unknown	03:05–05:45 (good, 2.67 h)	42.9° 06:20	9.11	57%	140.4°
2044-09-30 Fri	63	—	unknown	03:00–05:50 (good, 2.83 h)	42.9° 06:15	9.16	66%	133.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-09-01&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.