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 (50), 09-23 (45), 09-22 (38), 09-21 (31), 09-09 (25) — by astronomy; check the weather when the night is within four days.

2030-08-26astronomy score per night — click a bar for that night2030-09-24

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-08-26 Mon	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.27	5%	50.1°
2030-08-27 Tue	5	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.33	1%	60.8°
2030-08-28 Wed	6	—	unknown	05:15–05:45 (marginal, 0.5 h)	42.9° 08:30	7.39	0%	72.1°
2030-08-29 Thu	8	—	unknown	04:40–05:45 (marginal, 1.08 h)	42.9° 08:25	7.44	1%	83.9°
2030-08-30 Fri	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.5	5%	96.0°
2030-08-31 Sat	10	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.56	11%	108.2°
2030-09-01 Sun	12	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:10	7.61	18%	120.3°
2030-09-02 Mon	14	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:10	7.67	28%	131.8°
2030-09-03 Tue	15	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.72	39%	142.1°
2030-09-04 Wed	17	—	unknown	04:45–05:15 (good, 0.5 h)	42.9° 08:00	7.78	50%	149.8°
2030-09-05 Thu	19	—	unknown	04:40–05:15 (good, 0.58 h)	42.9° 07:55	7.83	62%	152.4°
2030-09-06 Fri	22	—	unknown	04:40–05:20 (good, 0.67 h)	42.9° 07:55	7.89	72%	148.7°
2030-09-07 Sat	23	—	unknown	04:35–05:20 (good, 0.75 h)	42.9° 07:50	7.94	82%	140.6°
2030-09-08 Sun	24	—	unknown	04:30–05:20 (good, 0.83 h)	42.9° 07:45	8.0	90%	130.2°
2030-09-09 Mon	25	—	unknown	04:35–05:25 (good, 0.83 h)	42.9° 07:40	8.05	95%	118.8°
2030-09-10 Tue	20	—	unknown	04:40–05:25 (good, 0.75 h)	42.9° 07:35	8.11	99%	107.0°
2030-09-11 Wed	17	—	unknown	04:50–05:25 (good, 0.58 h)	42.9° 07:35	8.16	100%	95.2°
2030-09-12 Thu	14	—	unknown	03:55–05:25 (marginal, 1.5 h)	42.9° 07:30	8.21	99%	83.6°
2030-09-13 Fri	11	—	unknown	04:00–05:30 (marginal, 1.5 h)	42.9° 07:25	8.27	95%	72.3°
2030-09-14 Sat	10	—	unknown	04:05–05:30 (marginal, 1.42 h)	42.9° 07:20	8.32	90%	61.5°
2030-09-15 Sun	9	—	unknown	04:05–05:30 (marginal, 1.42 h)	42.9° 07:15	8.37	84%	51.3°
2030-09-16 Mon	8	—	unknown	04:05–05:30 (marginal, 1.42 h)	42.9° 07:15	8.43	76%	42.0°
2030-09-17 Tue	10	—	unknown	03:50–05:35 (marginal, 1.75 h)	42.9° 07:10	8.48	68%	34.2°
2030-09-18 Wed	13	—	unknown	03:35–05:35 (marginal, 2.0 h)	42.9° 07:05	8.53	58%	28.9°
2030-09-19 Thu	18	—	unknown	03:20–05:35 (marginal, 2.25 h)	42.9° 07:00	8.58	49%	27.6°
2030-09-20 Fri	24	—	unknown	04:15–05:35 (good, 1.33 h)	42.9° 07:00	8.63	40%	30.8°
2030-09-21 Sat	31	—	unknown	04:00–05:35 (good, 1.58 h)	42.9° 06:55	8.69	30%	37.5°
2030-09-22 Sun	38	—	unknown	03:45–05:40 (good, 1.92 h)	42.9° 06:50	8.74	22%	46.3°
2030-09-23 Mon	45	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.79	14%	56.6°
2030-09-24 Tue	50	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:40	8.84	8%	67.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-08-26&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.