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: 02-20 (79), 02-21 (78), 02-19 (76), 02-22 (76), 02-23 (75) — by astronomy; check the weather when the night is within four days.

2041-02-11astronomy score per night — click a bar for that night2041-03-12

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-02-11 Mon	14	—	unknown	19:25–23:20 (marginal, 3.92 h)	42.9° 20:30	10.39	85%	35.6°
2041-02-12 Tue	14	—	unknown	19:25–22:40 (marginal, 3.25 h)	42.9° 20:25	10.35	91%	42.2°
2041-02-13 Wed	18	—	unknown	19:30–23:10 (marginal, 3.67 h)	42.9° 20:20	10.31	96%	50.4°
2041-02-14 Thu	24	—	unknown	19:30–23:25 (marginal, 3.92 h)	42.9° 20:20	10.27	99%	59.5°
2041-02-15 Fri	32	—	unknown	19:30–23:35 (marginal, 4.08 h)	42.9° 20:15	10.23	100%	69.1°
2041-02-16 Sat	41	—	unknown	19:30–20:45 (good, 1.25 h)	42.9° 20:10	10.19	99%	79.1°
2041-02-17 Sun	52	—	unknown	19:35–22:15 (good, 2.67 h)	42.9° 20:05	10.15	97%	89.3°
2041-02-18 Mon	72	—	unknown	19:35–22:55 (good, 3.33 h)	42.9° 20:00	10.11	93%	99.5°
2041-02-19 Tue	76	—	unknown	19:35–23:05 (good, 3.5 h)	42.9° 20:00	10.07	87%	109.8°
2041-02-20 Wed	79	—	unknown	19:35–23:05 (good, 3.5 h)	42.9° 19:55	10.03	80%	119.8°
2041-02-21 Thu	78	—	unknown	19:35–23:10 (good, 3.58 h)	42.9° 19:50	9.98	71%	129.5°
2041-02-22 Fri	76	—	unknown	19:40–23:05 (good, 3.42 h)	42.9° 19:45	9.94	61%	138.3°
2041-02-23 Sat	75	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:40	9.9	51%	145.1°
2041-02-24 Sun	73	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:40	9.85	40%	148.5°
2041-02-25 Mon	72	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:35	9.81	29%	146.6°
2041-02-26 Tue	69	—	unknown	19:45–22:50 (good, 3.08 h)	42.9° 19:30	9.77	20%	140.0°
2041-02-27 Wed	68	—	unknown	19:45–22:45 (good, 3.0 h)	42.9° 19:25	9.72	11%	130.2°
2041-02-28 Thu	66	—	unknown	19:45–22:40 (good, 2.92 h)	42.9° 19:25	9.68	5%	118.6°
2041-03-01 Fri	65	—	unknown	19:45–22:40 (good, 2.92 h)	42.9° 19:20	9.63	1%	106.2°
2041-03-02 Sat	62	—	unknown	19:50–22:35 (good, 2.75 h)	42.9° 19:15	9.58	0%	93.3°
2041-03-03 Sun	61	—	unknown	19:50–22:30 (good, 2.67 h)	42.9° 19:10	9.54	3%	80.6°
2041-03-04 Mon	57	—	unknown	19:50–22:25 (good, 2.58 h)	42.9° 19:05	9.49	8%	68.3°
2041-03-05 Tue	52	—	unknown	19:50–22:20 (good, 2.5 h)	42.9° 19:05	9.45	15%	56.8°
2041-03-06 Wed	44	—	unknown	19:50–22:10 (good, 2.33 h)	42.9° 19:00	9.4	23%	46.6°
2041-03-07 Thu	35	—	unknown	19:55–21:55 (good, 2.0 h)	42.9° 18:55	9.35	33%	38.3°
2041-03-08 Fri	26	—	unknown	19:55–20:45 (good, 0.83 h)	42.9° 18:50	9.3	43%	33.0°
2041-03-09 Sat	19	—	unknown	19:55–22:30 (marginal, 2.58 h)	42.9° 18:45	9.25	53%	31.7°
2041-03-10 Sun	14	—	unknown	19:55–22:15 (marginal, 2.33 h)	42.9° 18:45	9.21	62%	34.5°
2041-03-11 Mon	11	—	unknown	20:00–22:00 (marginal, 2.0 h)	42.9° 18:40	9.16	71%	40.4°
2041-03-12 Tue	11	—	unknown	20:00–21:50 (marginal, 1.83 h)	42.9° 18:35	9.11	80%	48.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-02-11&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.