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: 10-09 (76), 10-07 (74), 10-08 (74), 10-06 (72), 10-05 (70) — by astronomy; check the weather when the night is within four days.

2035-09-10astronomy score per night — click a bar for that night2035-10-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-09-10 Mon	27	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:40	8.1	62%	154.4°
2035-09-11 Tue	29	—	unknown	04:20–05:25 (good, 1.08 h)	42.9° 07:35	8.15	71%	148.2°
2035-09-12 Wed	30	—	unknown	04:15–05:25 (good, 1.17 h)	42.9° 07:30	8.2	80%	139.5°
2035-09-13 Thu	32	—	unknown	04:10–05:25 (good, 1.25 h)	42.9° 07:25	8.26	87%	129.6°
2035-09-14 Fri	33	—	unknown	04:15–05:30 (good, 1.25 h)	42.9° 07:20	8.31	93%	118.8°
2035-09-15 Sat	27	—	unknown	04:20–05:30 (good, 1.17 h)	42.9° 07:20	8.36	97%	107.5°
2035-09-16 Sun	23	—	unknown	04:30–05:30 (good, 1.0 h)	42.9° 07:15	8.42	100%	95.9°
2035-09-17 Mon	19	—	unknown	05:25–05:30 (good, 0.08 h)	42.9° 07:10	8.47	100%	83.9°
2035-09-18 Tue	15	—	unknown	03:40–05:35 (marginal, 1.92 h)	42.9° 07:05	8.52	98%	71.7°
2035-09-19 Wed	12	—	unknown	03:50–05:35 (marginal, 1.75 h)	42.9° 07:05	8.57	94%	59.5°
2035-09-20 Thu	9	—	unknown	03:55–05:35 (marginal, 1.67 h)	42.9° 07:00	8.62	87%	47.6°
2035-09-21 Fri	9	—	unknown	03:50–05:35 (marginal, 1.75 h)	42.9° 06:55	8.67	79%	36.6°
2035-09-22 Sat	11	—	unknown	03:35–05:40 (marginal, 2.08 h)	42.9° 06:50	8.73	69%	27.7°
2035-09-23 Sun	16	—	unknown	03:15–05:40 (marginal, 2.42 h)	42.9° 06:45	8.78	58%	23.7°
2035-09-24 Mon	23	—	unknown	03:00–05:40 (marginal, 2.67 h)	42.9° 06:45	8.83	46%	27.1°
2035-09-25 Tue	32	—	unknown	03:50–05:40 (good, 1.83 h)	42.9° 06:40	8.88	35%	35.8°
2035-09-26 Wed	42	—	unknown	03:30–05:45 (good, 2.25 h)	42.9° 06:35	8.93	25%	47.0°
2035-09-27 Thu	50	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:30	8.98	16%	59.2°
2035-09-28 Fri	56	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:25	9.02	8%	71.8°
2035-09-29 Sat	59	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.07	3%	84.5°
2035-09-30 Sun	61	—	unknown	03:05–05:45 (good, 2.67 h)	42.9° 06:20	9.12	0%	97.0°
2035-10-01 Mon	63	—	unknown	03:00–05:50 (good, 2.83 h)	42.9° 06:15	9.17	0%	109.3°
2035-10-02 Tue	65	—	unknown	02:55–05:50 (good, 2.92 h)	42.9° 06:10	9.22	2%	121.0°
2035-10-03 Wed	67	—	unknown	02:55–05:50 (good, 2.92 h)	42.9° 06:05	9.27	6%	132.2°
2035-10-04 Thu	68	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:05	9.31	12%	142.2°
2035-10-05 Fri	70	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 06:00	9.36	19%	150.5°
2035-10-06 Sat	72	—	unknown	02:40–05:55 (good, 3.25 h)	42.9° 05:55	9.41	27%	155.6°
2035-10-07 Sun	74	—	unknown	02:40–05:55 (good, 3.25 h)	42.9° 05:50	9.45	36%	155.5°
2035-10-08 Mon	74	—	unknown	02:35–05:55 (good, 3.33 h)	42.9° 05:50	9.5	45%	150.6°
2035-10-09 Tue	76	—	unknown	02:30–05:55 (good, 3.42 h)	42.9° 05:45	9.55	55%	142.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-09-10&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.