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: 10-11 (80), 10-10 (78), 10-09 (76), 10-08 (72), 10-07 (65) — by astronomy; check the weather when the night is within four days.

2034-09-12astronomy score per night — click a bar for that night2034-10-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2034-09-12 Tue	30	—	unknown	04:15–05:25 (good, 1.17 h)	42.9° 07:30	8.22	0%	90.1°
2034-09-13 Wed	33	—	unknown	04:10–05:30 (good, 1.33 h)	42.9° 07:25	8.27	2%	101.6°
2034-09-14 Thu	35	—	unknown	04:05–05:30 (good, 1.42 h)	42.9° 07:20	8.32	5%	112.9°
2034-09-15 Fri	36	—	unknown	04:05–05:30 (good, 1.42 h)	42.9° 07:15	8.38	10%	123.7°
2034-09-16 Sat	37	—	unknown	04:00–05:30 (good, 1.5 h)	42.9° 07:15	8.43	17%	134.0°
2034-09-17 Sun	39	—	unknown	03:55–05:35 (good, 1.67 h)	42.9° 07:10	8.48	24%	143.4°
2034-09-18 Mon	41	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 07:05	8.53	33%	151.3°
2034-09-19 Tue	43	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.58	42%	156.0°
2034-09-20 Wed	44	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.64	51%	155.7°
2034-09-21 Thu	45	—	unknown	03:40–05:35 (good, 1.92 h)	42.9° 06:55	8.69	61%	150.3°
2034-09-22 Fri	48	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.74	71%	141.7°
2034-09-23 Sat	50	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.79	79%	131.3°
2034-09-24 Sun	51	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:40	8.84	87%	119.9°
2034-09-25 Mon	48	—	unknown	03:40–05:40 (good, 2.0 h)	42.9° 06:40	8.89	94%	107.6°
2034-09-26 Tue	36	—	unknown	03:50–05:45 (good, 1.92 h)	42.9° 06:35	8.94	98%	94.8°
2034-09-27 Wed	28	—	unknown	05:05–05:45 (good, 0.67 h)	42.9° 06:30	8.99	100%	81.6°
2034-09-28 Thu	21	—	unknown	03:05–05:45 (marginal, 2.67 h)	42.9° 06:25	9.04	99%	68.3°
2034-09-29 Fri	15	—	unknown	03:20–05:45 (marginal, 2.42 h)	42.9° 06:20	9.09	95%	55.1°
2034-09-30 Sat	11	—	unknown	03:25–05:50 (marginal, 2.42 h)	42.9° 06:20	9.13	89%	42.5°
2034-10-01 Sun	10	—	unknown	03:20–05:50 (marginal, 2.5 h)	42.9° 06:15	9.18	80%	31.6°
2034-10-02 Mon	14	—	unknown	02:55–05:50 (marginal, 2.92 h)	42.9° 06:10	9.23	70%	24.5°
2034-10-03 Tue	21	—	unknown	02:35–05:50 (marginal, 3.25 h)	42.9° 06:05	9.28	59%	24.4°
2034-10-04 Wed	31	—	unknown	02:20–05:50 (marginal, 3.5 h)	42.9° 06:05	9.33	48%	30.9°
2034-10-05 Thu	43	—	unknown	03:05–05:55 (good, 2.83 h)	42.9° 06:00	9.37	37%	40.9°
2034-10-06 Fri	55	—	unknown	02:50–05:55 (good, 3.08 h)	42.9° 05:55	9.42	27%	52.0°
2034-10-07 Sat	65	—	unknown	02:35–05:55 (good, 3.33 h)	42.9° 05:50	9.47	18%	63.6°
2034-10-08 Sun	72	—	unknown	02:35–05:55 (good, 3.33 h)	42.9° 05:45	9.51	11%	75.2°
2034-10-09 Mon	76	—	unknown	02:30–06:00 (good, 3.5 h)	42.9° 05:45	9.56	6%	86.8°
2034-10-10 Tue	78	—	unknown	02:25–06:00 (good, 3.58 h)	42.9° 05:40	9.6	2%	98.3°
2034-10-11 Wed	80	—	unknown	02:20–06:00 (good, 3.67 h)	42.9° 05:35	9.65	0%	109.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2034-09-12&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.