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: 10-27 (89), 10-28 (89), 10-26 (87), 10-25 (83), 10-12 (80) — by astronomy; check the weather when the night is within four days.

2035-09-29astronomy score per night — click a bar for that night2035-10-28

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2035-10-10 Wed	78	—	unknown	02:25–06:00 (good, 3.58 h)	42.9° 05:40	9.59	64%	133.2°
2035-10-11 Thu	79	—	unknown	02:20–06:00 (good, 3.67 h)	42.9° 05:35	9.64	73%	122.8°
2035-10-12 Fri	80	—	unknown	02:30–06:00 (good, 3.5 h)	42.9° 05:30	9.68	81%	111.8°
2035-10-13 Sat	76	—	unknown	02:35–06:00 (good, 3.42 h)	42.9° 05:30	9.73	89%	100.3°
2035-10-14 Sun	70	—	unknown	02:55–06:05 (good, 3.17 h)	42.9° 05:25	9.77	94%	88.4°
2035-10-15 Mon	44	—	unknown	04:30–06:05 (good, 1.58 h)	42.9° 05:20	9.81	98%	76.2°
2035-10-16 Tue	32	—	unknown	02:00–06:05 (marginal, 4.08 h)	42.9° 05:15	9.86	100%	63.8°
2035-10-17 Wed	21	—	unknown	02:20–06:05 (marginal, 3.75 h)	42.9° 05:10	9.9	99%	51.5°
2035-10-18 Thu	14	—	unknown	03:40–06:05 (marginal, 2.42 h)	42.9° 05:10	9.94	96%	39.8°
2035-10-19 Fri	11	—	unknown	05:20–06:10 (marginal, 0.83 h)	42.9° 05:05	9.98	90%	29.9°
2035-10-20 Sat	14	—	unknown	02:05–06:10 (marginal, 4.08 h)	42.9° 05:00	10.03	82%	24.2°
2035-10-21 Sun	22	—	unknown	01:35–06:10 (marginal, 4.58 h)	42.9° 04:55	10.07	72%	25.8°
2035-10-22 Mon	34	—	unknown	01:15–06:10 (marginal, 4.92 h)	42.9° 04:55	10.11	61%	33.7°
2035-10-23 Tue	51	—	unknown	02:05–05:45 (good, 3.67 h)	42.9° 04:50	10.15	50%	44.4°
2035-10-24 Wed	70	—	unknown	01:45–06:15 (good, 4.5 h)	42.9° 04:45	10.19	38%	56.3°
2035-10-25 Thu	83	—	unknown	01:25–06:15 (good, 4.83 h)	42.9° 04:40	10.23	28%	68.6°
2035-10-26 Fri	87	—	unknown	01:25–06:15 (good, 4.83 h)	42.9° 04:35	10.27	19%	81.0°
2035-10-27 Sat	89	—	unknown	01:20–05:15 (good, 4.92 h)	42.9° 03:35	10.31	11%	93.3°
2035-10-28 Sun	89	—	unknown	00:15–05:20 (good, 5.08 h)	42.9° 03:30	10.35	5%	105.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-09-29&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.