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: 10-18 (89), 10-19 (89), 10-20 (89), 10-21 (89), 10-22 (89) — by astronomy; check the weather when the night is within four days.

2047-10-18astronomy score per night — click a bar for that night2047-11-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2047-10-18 Fri	89	—	unknown	01:55–06:05 (good, 4.17 h)	42.9° 05:10	9.95	0%	112.7°
2047-10-19 Sat	89	—	unknown	01:50–06:10 (good, 4.33 h)	42.9° 05:05	9.99	1%	125.1°
2047-10-20 Sun	89	—	unknown	01:45–06:10 (good, 4.42 h)	42.9° 05:00	10.03	5%	136.5°
2047-10-21 Mon	89	—	unknown	01:45–06:10 (good, 4.42 h)	42.9° 04:55	10.07	11%	145.4°
2047-10-22 Tue	89	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:55	10.11	20%	149.8°
2047-10-23 Wed	89	—	unknown	01:35–06:15 (good, 4.67 h)	42.9° 04:50	10.15	30%	148.3°
2047-10-24 Thu	89	—	unknown	01:30–06:15 (good, 4.75 h)	42.9° 04:45	10.19	40%	141.9°
2047-10-25 Fri	89	—	unknown	01:25–06:15 (good, 4.83 h)	42.9° 04:40	10.23	51%	132.9°
2047-10-26 Sat	89	—	unknown	01:25–05:15 (good, 4.83 h)	42.9° 03:35	10.27	62%	122.8°
2047-10-27 Sun	89	—	unknown	00:30–05:15 (good, 4.75 h)	42.9° 03:35	10.31	71%	112.2°
2047-10-28 Mon	89	—	unknown	00:35–05:20 (good, 4.75 h)	42.9° 03:30	10.35	80%	101.6°
2047-10-29 Tue	89	—	unknown	00:45–05:20 (good, 4.58 h)	42.9° 03:25	10.39	87%	90.9°
2047-10-30 Wed	83	—	unknown	01:55–05:20 (good, 3.42 h)	42.9° 03:20	10.42	93%	80.4°
2047-10-31 Thu	50	—	unknown	04:10–05:20 (good, 1.17 h)	42.9° 03:20	10.46	97%	70.1°
2047-11-01 Fri	36	—	unknown	00:10–05:20 (marginal, 5.17 h)	42.9° 03:15	10.5	99%	60.2°
2047-11-02 Sat	26	—	unknown	00:30–05:25 (marginal, 4.92 h)	42.9° 03:10	10.53	100%	50.8°
2047-11-03 Sun	18	—	unknown	02:40–05:25 (marginal, 2.75 h)	42.9° 03:05	10.57	99%	42.2°
2047-11-04 Mon	13	—	unknown	04:35–05:25 (marginal, 0.83 h)	42.9° 03:00	10.61	96%	35.2°
2047-11-05 Tue	12	—	unknown	—	42.9° 03:00	10.64	91%	30.7°
2047-11-06 Wed	16	—	unknown	23:55–03:15 (marginal, 3.33 h)	42.9° 02:55	10.67	85%	30.2°
2047-11-07 Thu	26	—	unknown	23:25–05:30 (marginal, 6.08 h)	42.9° 02:50	10.71	77%	33.7°
2047-11-08 Fri	41	—	unknown	23:05–05:30 (marginal, 6.42 h)	42.9° 02:45	10.74	69%	40.4°
2047-11-09 Sat	59	—	unknown	00:00–02:30 (good, 2.5 h)	42.9° 02:40	10.77	59%	49.2°
2047-11-10 Sun	74	—	unknown	23:25–05:10 (good, 5.75 h)	42.9° 02:40	10.81	49%	59.3°
2047-11-11 Mon	85	—	unknown	23:20–05:35 (good, 6.25 h)	42.9° 02:35	10.84	38%	70.3°
2047-11-12 Tue	88	—	unknown	23:15–05:35 (good, 6.33 h)	42.9° 02:30	10.87	28%	82.0°
2047-11-13 Wed	89	—	unknown	23:10–05:35 (good, 6.42 h)	42.9° 02:25	10.9	18%	94.3°
2047-11-14 Thu	89	—	unknown	23:10–05:35 (good, 6.42 h)	42.9° 02:25	10.93	10%	106.8°
2047-11-15 Fri	89	—	unknown	23:05–05:35 (good, 6.5 h)	42.9° 02:20	10.96	4%	119.4°
2047-11-16 Sat	89	—	unknown	23:00–05:35 (good, 6.58 h)	42.9° 02:15	10.98	1%	131.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2047-10-18&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.