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: 02-02 (89), 02-03 (89), 02-04 (89), 02-05 (89), 02-06 (89) — by astronomy; check the weather when the night is within four days.

2029-01-20astronomy score per night — click a bar for that night2029-02-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2029-01-20 Sat	86	—	unknown	19:00–01:15 (good, 6.25 h)	42.9° 21:55	11.1	33%	77.1°
2029-01-21 Sun	82	—	unknown	19:05–01:10 (good, 6.08 h)	42.9° 21:50	11.08	42%	67.1°
2029-01-22 Mon	68	—	unknown	19:50–00:45 (good, 4.92 h)	42.9° 21:50	11.05	51%	57.3°
2029-01-23 Tue	54	—	unknown	19:05–01:35 (marginal, 6.5 h)	42.9° 21:45	11.02	61%	48.1°
2029-01-24 Wed	37	—	unknown	19:05–01:20 (marginal, 6.25 h)	42.9° 21:40	10.99	70%	39.7°
2029-01-25 Thu	23	—	unknown	19:05–01:00 (marginal, 5.92 h)	42.9° 21:35	10.96	79%	33.3°
2029-01-26 Fri	14	—	unknown	23:45–00:20 (marginal, 0.58 h)	42.9° 21:30	10.94	87%	30.4°
2029-01-27 Sat	13	—	unknown	19:10–19:20 (marginal, 0.17 h)	42.9° 21:30	10.91	93%	32.6°
2029-01-28 Sun	16	—	unknown	19:10–21:20 (marginal, 2.17 h)	42.9° 21:25	10.88	98%	39.3°
2029-01-29 Mon	25	—	unknown	19:10–23:50 (marginal, 4.67 h)	42.9° 21:20	10.84	100%	49.0°
2029-01-30 Tue	38	—	unknown	19:10–00:30 (marginal, 5.33 h)	42.9° 21:15	10.81	99%	60.3°
2029-01-31 Wed	74	—	unknown	19:15–21:25 (good, 2.17 h)	42.9° 21:15	10.78	96%	72.6°
2029-02-01 Thu	88	—	unknown	19:15–23:30 (good, 4.25 h)	42.9° 21:10	10.75	90%	85.2°
2029-02-02 Fri	89	—	unknown	19:15–00:05 (good, 4.83 h)	42.9° 21:05	10.71	82%	97.8°
2029-02-03 Sat	89	—	unknown	19:15–00:10 (good, 4.92 h)	42.9° 21:00	10.68	72%	110.2°
2029-02-04 Sun	89	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 20:55	10.65	61%	122.0°
2029-02-05 Mon	89	—	unknown	19:20–00:10 (good, 4.83 h)	42.9° 20:55	10.61	50%	132.7°
2029-02-06 Tue	89	—	unknown	19:20–00:10 (good, 4.83 h)	42.9° 20:50	10.58	39%	141.8°
2029-02-07 Wed	89	—	unknown	19:20–00:05 (good, 4.75 h)	42.9° 20:45	10.54	28%	147.9°
2029-02-08 Thu	89	—	unknown	19:20–00:00 (good, 4.67 h)	42.9° 20:40	10.5	19%	149.5°
2029-02-09 Fri	89	—	unknown	19:25–23:55 (good, 4.5 h)	42.9° 20:35	10.47	12%	146.3°
2029-02-10 Sat	89	—	unknown	19:25–23:50 (good, 4.42 h)	42.9° 20:35	10.43	6%	139.5°
2029-02-11 Sun	89	—	unknown	19:25–23:50 (good, 4.42 h)	42.9° 20:30	10.39	2%	130.8°
2029-02-12 Mon	89	—	unknown	19:25–23:45 (good, 4.33 h)	42.9° 20:25	10.35	0%	121.1°
2029-02-13 Tue	89	—	unknown	19:30–23:40 (good, 4.17 h)	42.9° 20:20	10.31	0%	111.0°
2029-02-14 Wed	89	—	unknown	19:30–23:35 (good, 4.08 h)	42.9° 20:20	10.27	2%	100.7°
2029-02-15 Thu	87	—	unknown	19:30–23:35 (good, 4.08 h)	42.9° 20:15	10.23	6%	90.4°
2029-02-16 Fri	84	—	unknown	19:30–23:30 (good, 4.0 h)	42.9° 20:10	10.19	11%	80.1°
2029-02-17 Sat	76	—	unknown	19:35–23:25 (good, 3.83 h)	42.9° 20:05	10.15	18%	70.1°
2029-02-18 Sun	67	—	unknown	19:35–23:20 (good, 3.75 h)	42.9° 20:00	10.11	25%	60.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2029-01-20&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.