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: 10-06 (71), 10-05 (70), 10-07 (70), 10-04 (69), 10-03 (67) — by astronomy; check the weather when the night is within four days.

2030-09-17astronomy score per night — click a bar for that night2030-10-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2030-09-25 Wed	52	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:40	8.89	3%	79.4°
2030-09-26 Thu	55	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:35	8.94	0%	91.6°
2030-09-27 Fri	56	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:30	8.99	0%	104.1°
2030-09-28 Sat	59	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.04	3%	116.5°
2030-09-29 Sun	60	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:20	9.08	8%	128.6°
2030-09-30 Mon	62	—	unknown	03:05–05:50 (good, 2.75 h)	42.9° 06:20	9.13	16%	139.7°
2030-10-01 Tue	63	—	unknown	03:00–05:50 (good, 2.83 h)	42.9° 06:15	9.18	25%	148.5°
2030-10-02 Wed	65	—	unknown	02:55–05:50 (good, 2.92 h)	42.9° 06:10	9.23	36%	152.6°
2030-10-03 Thu	67	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:05	9.28	47%	150.3°
2030-10-04 Fri	69	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:00	9.32	58%	142.9°
2030-10-05 Sat	70	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 06:00	9.37	69%	133.0°
2030-10-06 Sun	71	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 05:55	9.42	79%	121.9°
2030-10-07 Mon	70	—	unknown	02:50–05:55 (good, 3.08 h)	42.9° 05:50	9.46	87%	110.4°
2030-10-08 Tue	65	—	unknown	03:00–05:55 (good, 2.92 h)	42.9° 05:45	9.51	93%	98.8°
2030-10-09 Wed	46	—	unknown	03:40–06:00 (good, 2.33 h)	42.9° 05:45	9.56	97%	87.3°
2030-10-10 Thu	35	—	unknown	05:20–06:00 (good, 0.67 h)	42.9° 05:40	9.6	100%	76.0°
2030-10-11 Fri	26	—	unknown	02:20–06:00 (marginal, 3.67 h)	42.9° 05:35	9.65	100%	65.0°
2030-10-12 Sat	19	—	unknown	02:35–06:00 (marginal, 3.42 h)	42.9° 05:30	9.69	98%	54.6°
2030-10-13 Sun	14	—	unknown	02:50–06:00 (marginal, 3.17 h)	42.9° 05:25	9.74	94%	44.9°
2030-10-14 Mon	12	—	unknown	03:50–06:05 (marginal, 2.25 h)	42.9° 05:25	9.78	89%	36.4°
2030-10-15 Tue	12	—	unknown	02:30–06:05 (marginal, 3.58 h)	42.9° 05:20	9.82	82%	30.0°
2030-10-16 Wed	17	—	unknown	02:00–06:05 (marginal, 4.08 h)	42.9° 05:15	9.87	75%	27.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-09-17&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.