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: 10-13 (83), 10-12 (82), 10-11 (80), 10-10 (77), 10-09 (71) — by astronomy; check the weather when the night is within four days.

2042-09-14astronomy score per night — click a bar for that night2042-10-13

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-09-14 Sun	35	—	unknown	04:05–05:30 (good, 1.42 h)	42.9° 07:20	8.33	0%	95.6°
2042-09-15 Mon	36	—	unknown	04:05–05:30 (good, 1.42 h)	42.9° 07:15	8.38	2%	105.4°
2042-09-16 Tue	37	—	unknown	04:00–05:30 (good, 1.5 h)	42.9° 07:15	8.43	6%	115.0°
2042-09-17 Wed	39	—	unknown	03:55–05:35 (good, 1.67 h)	42.9° 07:10	8.48	11%	124.1°
2042-09-18 Thu	41	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 07:05	8.54	18%	132.5°
2042-09-19 Fri	43	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 07:00	8.59	25%	139.7°
2042-09-20 Sat	44	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.64	34%	144.7°
2042-09-21 Sun	45	—	unknown	03:40–05:35 (good, 1.92 h)	42.9° 06:55	8.69	44%	146.6°
2042-09-22 Mon	48	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.74	54%	144.5°
2042-09-23 Tue	50	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.79	64%	138.7°
2042-09-24 Wed	51	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:40	8.84	74%	130.4°
2042-09-25 Thu	52	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:40	8.89	83%	120.2°
2042-09-26 Fri	52	—	unknown	03:35–05:45 (good, 2.17 h)	42.9° 06:35	8.94	91%	108.9°
2042-09-27 Sat	48	—	unknown	03:40–05:45 (good, 2.08 h)	42.9° 06:30	8.99	96%	96.8°
2042-09-28 Sun	31	—	unknown	04:40–05:45 (good, 1.08 h)	42.9° 06:25	9.04	100%	84.2°
2042-09-29 Mon	23	—	unknown	03:00–05:45 (marginal, 2.75 h)	42.9° 06:20	9.09	100%	71.7°
2042-09-30 Tue	16	—	unknown	03:10–05:50 (marginal, 2.67 h)	42.9° 06:20	9.14	97%	59.6°
2042-10-01 Wed	12	—	unknown	03:20–05:50 (marginal, 2.5 h)	42.9° 06:15	9.19	91%	48.6°
2042-10-02 Thu	11	—	unknown	03:15–05:50 (marginal, 2.58 h)	42.9° 06:10	9.23	83%	39.7°
2042-10-03 Fri	14	—	unknown	02:55–05:50 (marginal, 2.92 h)	42.9° 06:05	9.28	73%	34.4°
2042-10-04 Sat	19	—	unknown	02:35–05:50 (marginal, 3.25 h)	42.9° 06:05	9.33	63%	33.8°
2042-10-05 Sun	29	—	unknown	02:15–05:55 (marginal, 3.67 h)	42.9° 06:00	9.38	52%	37.9°
2042-10-06 Mon	41	—	unknown	03:05–05:55 (good, 2.83 h)	42.9° 05:55	9.42	41%	45.0°
2042-10-07 Tue	53	—	unknown	02:50–05:55 (good, 3.08 h)	42.9° 05:50	9.47	32%	53.7°
2042-10-08 Wed	63	—	unknown	02:35–05:55 (good, 3.33 h)	42.9° 05:45	9.51	23%	63.2°
2042-10-09 Thu	71	—	unknown	02:30–06:00 (good, 3.5 h)	42.9° 05:45	9.56	15%	73.0°
2042-10-10 Fri	77	—	unknown	02:25–06:00 (good, 3.58 h)	42.9° 05:40	9.61	9%	83.0°
2042-10-11 Sat	80	—	unknown	02:20–06:00 (good, 3.67 h)	42.9° 05:35	9.65	4%	93.0°
2042-10-12 Sun	82	—	unknown	02:15–06:00 (good, 3.75 h)	42.9° 05:30	9.69	1%	102.9°
2042-10-13 Mon	83	—	unknown	02:15–06:00 (good, 3.75 h)	42.9° 05:25	9.74	0%	112.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-09-14&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.