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.

2031-10-15astronomy score per night — click a bar for that night2031-11-13

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-10-15 Wed	86	—	unknown	02:05–06:05 (good, 4.0 h)	42.9° 05:20	9.81	0%	109.6°
2031-10-16 Thu	88	—	unknown	02:00–06:05 (good, 4.08 h)	42.9° 05:15	9.86	0%	121.3°
2031-10-17 Fri	89	—	unknown	02:00–06:05 (good, 4.08 h)	42.9° 05:10	9.9	3%	132.7°
2031-10-18 Sat	89	—	unknown	01:55–06:05 (good, 4.17 h)	42.9° 05:10	9.94	8%	143.2°
2031-10-19 Sun	89	—	unknown	01:50–06:10 (good, 4.33 h)	42.9° 05:05	9.98	15%	151.3°
2031-10-20 Mon	89	—	unknown	01:45–06:10 (good, 4.42 h)	42.9° 05:00	10.02	24%	154.3°
2031-10-21 Tue	89	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:55	10.07	34%	150.6°
2031-10-22 Wed	89	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:55	10.11	46%	142.1°
2031-10-23 Thu	89	—	unknown	01:35–06:15 (good, 4.67 h)	42.9° 04:50	10.15	57%	131.1°
2031-10-24 Fri	89	—	unknown	01:35–06:15 (good, 4.67 h)	42.9° 04:45	10.19	68%	119.2°
2031-10-25 Sat	89	—	unknown	01:40–05:15 (good, 4.58 h)	42.9° 03:40	10.23	78%	106.8°
2031-10-26 Sun	89	—	unknown	00:50–05:15 (good, 4.42 h)	42.9° 03:35	10.27	87%	94.3°
2031-10-27 Mon	80	—	unknown	01:55–05:15 (good, 3.33 h)	42.9° 03:35	10.31	93%	81.8°
2031-10-28 Tue	47	—	unknown	04:20–05:20 (good, 1.0 h)	42.9° 03:30	10.34	98%	69.6°
2031-10-29 Wed	33	—	unknown	00:25–05:20 (marginal, 4.92 h)	42.9° 03:25	10.38	100%	57.9°
2031-10-30 Thu	22	—	unknown	01:20–05:20 (marginal, 4.0 h)	42.9° 03:20	10.42	100%	46.8°
2031-10-31 Fri	15	—	unknown	03:35–05:20 (marginal, 1.75 h)	42.9° 03:15	10.46	97%	37.1°
2031-11-01 Sat	12	—	unknown	—	42.9° 03:15	10.49	93%	29.5°
2031-11-02 Sun	14	—	unknown	00:25–01:10 (marginal, 0.75 h)	42.9° 03:10	10.53	87%	25.8°
2031-11-03 Mon	21	—	unknown	23:50–05:25 (marginal, 5.58 h)	42.9° 03:05	10.57	80%	27.2°
2031-11-04 Tue	31	—	unknown	23:30–05:25 (marginal, 5.92 h)	42.9° 03:00	10.6	72%	32.9°
2031-11-05 Wed	46	—	unknown	23:15–05:25 (marginal, 6.17 h)	42.9° 03:00	10.64	63%	41.0°
2031-11-06 Thu	65	—	unknown	00:05–04:10 (good, 4.08 h)	42.9° 02:55	10.67	54%	50.4°
2031-11-07 Fri	81	—	unknown	23:35–05:30 (good, 5.92 h)	42.9° 02:50	10.7	44%	60.5°
2031-11-08 Sat	86	—	unknown	23:30–05:30 (good, 6.0 h)	42.9° 02:45	10.74	35%	71.1°
2031-11-09 Sun	88	—	unknown	23:30–05:30 (good, 6.0 h)	42.9° 02:40	10.77	26%	82.1°
2031-11-10 Mon	89	—	unknown	23:25–05:30 (good, 6.08 h)	42.9° 02:40	10.8	17%	93.4°
2031-11-11 Tue	89	—	unknown	23:20–05:35 (good, 6.25 h)	42.9° 02:35	10.83	10%	105.0°
2031-11-12 Wed	89	—	unknown	23:15–05:35 (good, 6.33 h)	42.9° 02:30	10.86	5%	116.8°
2031-11-13 Thu	89	—	unknown	23:10–05:35 (good, 6.42 h)	42.9° 02:25	10.89	1%	128.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-10-15&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.