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: 10-31 (89), 11-01 (89), 11-02 (89), 11-03 (89), 11-04 (89) — by astronomy; check the weather when the night is within four days.

2041-10-31astronomy score per night — click a bar for that night2041-11-29

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-10-31 Thu	89	—	unknown	00:00–05:20 (good, 5.33 h)	42.9° 03:15	10.48	44%	129.9°
2041-11-01 Fri	89	—	unknown	23:55–05:25 (good, 5.5 h)	42.9° 03:10	10.51	55%	119.4°
2041-11-02 Sat	89	—	unknown	00:05–05:25 (good, 5.33 h)	42.9° 03:10	10.55	66%	107.9°
2041-11-03 Sun	89	—	unknown	00:10–05:25 (good, 5.25 h)	42.9° 03:05	10.59	76%	95.9°
2041-11-04 Mon	89	—	unknown	00:35–05:25 (good, 4.83 h)	42.9° 03:00	10.62	86%	83.6°
2041-11-05 Tue	83	—	unknown	02:30–05:25 (good, 2.92 h)	42.9° 02:55	10.66	93%	71.4°
2041-11-06 Wed	44	—	unknown	23:45–05:30 (marginal, 5.75 h)	42.9° 02:50	10.69	98%	59.6°
2041-11-07 Thu	28	—	unknown	00:20–05:30 (marginal, 5.17 h)	42.9° 02:50	10.72	100%	48.8°
2041-11-08 Fri	18	—	unknown	03:05–05:30 (marginal, 2.42 h)	42.9° 02:45	10.76	99%	39.7°
2041-11-09 Sat	13	—	unknown	05:20–05:25 (marginal, 0.08 h)	42.9° 02:40	10.79	96%	33.9°
2041-11-10 Sun	13	—	unknown	—	42.9° 02:35	10.82	91%	32.6°
2041-11-11 Mon	22	—	unknown	23:20–05:25 (marginal, 6.08 h)	42.9° 02:30	10.85	84%	35.9°
2041-11-12 Tue	35	—	unknown	22:55–05:35 (marginal, 6.67 h)	42.9° 02:30	10.88	76%	42.5°
2041-11-13 Wed	52	—	unknown	22:40–05:35 (marginal, 6.92 h)	42.9° 02:25	10.91	67%	50.9°
2041-11-14 Thu	66	—	unknown	23:30–03:50 (good, 4.33 h)	42.9° 02:20	10.94	57%	60.1°
2041-11-15 Fri	81	—	unknown	23:00–05:05 (good, 6.08 h)	42.9° 02:15	10.97	48%	69.7°
2041-11-16 Sat	86	—	unknown	23:00–05:15 (good, 6.25 h)	42.9° 02:15	11.0	38%	79.6°
2041-11-17 Sun	88	—	unknown	22:55–05:20 (good, 6.42 h)	42.9° 02:10	11.03	29%	89.5°
2041-11-18 Mon	89	—	unknown	22:50–05:20 (good, 6.5 h)	42.9° 02:05	11.05	21%	99.5°
2041-11-19 Tue	89	—	unknown	22:45–05:20 (good, 6.58 h)	42.9° 02:00	11.08	14%	109.5°
2041-11-20 Wed	89	—	unknown	22:45–05:15 (good, 6.5 h)	42.9° 01:55	11.1	8%	119.4°
2041-11-21 Thu	89	—	unknown	22:40–05:10 (good, 6.5 h)	42.9° 01:55	11.13	3%	128.8°
2041-11-22 Fri	89	—	unknown	22:35–05:10 (good, 6.58 h)	42.9° 01:50	11.15	1%	137.3°
2041-11-23 Sat	89	—	unknown	22:30–05:05 (good, 6.58 h)	42.9° 01:45	11.18	0%	144.0°
2041-11-24 Sun	89	—	unknown	22:25–05:00 (good, 6.58 h)	42.9° 01:40	11.2	2%	147.4°
2041-11-25 Mon	89	—	unknown	22:25–04:55 (good, 6.5 h)	42.9° 01:35	11.22	6%	146.2°
2041-11-26 Tue	89	—	unknown	22:20–04:50 (good, 6.5 h)	42.9° 01:35	11.24	12%	140.6°
2041-11-27 Wed	89	—	unknown	22:15–04:50 (good, 6.58 h)	42.9° 01:30	11.26	20%	132.1°
2041-11-28 Thu	89	—	unknown	22:10–04:45 (good, 6.58 h)	42.9° 01:25	11.28	29%	121.8°
2041-11-29 Fri	89	—	unknown	22:10–04:40 (good, 6.5 h)	42.9° 01:20	11.3	40%	110.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-10-31&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.