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: 10-17 (89), 10-18 (89), 10-19 (89), 10-20 (89), 10-21 (89) — by astronomy; check the weather when the night is within four days.

2026-10-10astronomy score per night — click a bar for that night2026-11-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2026-10-10 Sat	78	99	77	02:25–06:00 (good, 3.58 h)	42.9° 05:40	9.6	0%	112.0°
2026-10-11 Sun	80	0	0	—	42.9° 05:35	9.64	2%	122.0°
2026-10-12 Mon	82	0	0	—	42.9° 05:30	9.69	6%	131.2°
2026-10-13 Tue	83	0	0	03:00–06:00 (good, 3.0 h)	42.9° 05:25	9.73	11%	138.8°
2026-10-14 Wed	85	—	unknown	02:10–06:05 (good, 3.92 h)	42.9° 05:25	9.78	17%	144.3°
2026-10-15 Thu	86	—	unknown	02:05–06:05 (good, 4.0 h)	42.9° 05:20	9.82	25%	146.7°
2026-10-16 Fri	88	—	unknown	02:00–06:05 (good, 4.08 h)	42.9° 05:15	9.86	34%	145.4°
2026-10-17 Sat	89	—	unknown	01:55–06:05 (good, 4.17 h)	42.9° 05:10	9.91	43%	140.9°
2026-10-18 Sun	89	—	unknown	01:55–06:05 (good, 4.17 h)	42.9° 05:05	9.95	52%	134.0°
2026-10-19 Mon	89	—	unknown	01:50–06:10 (good, 4.33 h)	42.9° 05:05	9.99	62%	125.6°
2026-10-20 Tue	89	—	unknown	01:55–06:10 (good, 4.25 h)	42.9° 05:00	10.03	71%	116.2°
2026-10-21 Wed	89	—	unknown	01:55–06:10 (good, 4.25 h)	42.9° 04:55	10.08	80%	106.0°
2026-10-22 Thu	87	—	unknown	02:05–06:10 (good, 4.08 h)	42.9° 04:50	10.12	87%	95.3°
2026-10-23 Fri	78	—	unknown	02:55–06:15 (good, 3.33 h)	42.9° 04:50	10.16	94%	84.1°
2026-10-24 Sat	47	—	unknown	03:55–05:15 (good, 1.33 h)	42.9° 03:45	10.2	98%	72.7°
2026-10-25 Sun	32	—	unknown	00:35–05:15 (marginal, 4.67 h)	42.9° 03:40	10.24	100%	61.4°
2026-10-26 Mon	22	—	unknown	00:55–05:15 (marginal, 4.33 h)	42.9° 03:35	10.28	99%	50.6°
2026-10-27 Tue	15	—	unknown	03:00–05:15 (marginal, 2.25 h)	42.9° 03:30	10.31	96%	41.3°
2026-10-28 Wed	13	—	unknown	04:10–05:20 (marginal, 1.17 h)	42.9° 03:30	10.35	90%	34.9°
2026-10-29 Thu	17	—	unknown	00:20–05:20 (marginal, 5.0 h)	42.9° 03:25	10.39	81%	33.3°
2026-10-30 Fri	29	—	unknown	23:50–05:20 (marginal, 5.5 h)	42.9° 03:20	10.43	71%	37.1°
2026-10-31 Sat	46	—	unknown	23:30–05:20 (marginal, 5.83 h)	42.9° 03:15	10.47	60%	44.7°
2026-11-01 Sun	65	—	unknown	00:20–05:10 (good, 4.83 h)	42.9° 03:10	10.5	49%	54.4°
2026-11-02 Mon	80	—	unknown	23:55–05:25 (good, 5.5 h)	42.9° 03:10	10.54	38%	65.1°
2026-11-03 Tue	86	—	unknown	23:50–05:25 (good, 5.58 h)	42.9° 03:05	10.57	28%	76.1°
2026-11-04 Wed	89	—	unknown	23:45–05:25 (good, 5.67 h)	42.9° 03:00	10.61	19%	87.2°
2026-11-05 Thu	89	—	unknown	23:40–05:25 (good, 5.75 h)	42.9° 02:55	10.64	12%	98.2°
2026-11-06 Fri	89	—	unknown	23:40–05:30 (good, 5.83 h)	42.9° 02:55	10.68	6%	108.9°
2026-11-07 Sat	89	—	unknown	23:35–05:30 (good, 5.92 h)	42.9° 02:50	10.71	2%	119.0°
2026-11-08 Sun	89	—	unknown	23:30–05:30 (good, 6.0 h)	42.9° 02:45	10.74	0%	128.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-10-10&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.