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: 02-17 (84), 02-18 (80), 02-19 (73), 02-20 (62), 03-05 (58) — by astronomy; check the weather when the night is within four days.

2037-02-17astronomy score per night — click a bar for that night2037-03-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-02-17 Tue	84	—	unknown	19:35–23:25 (good, 3.83 h)	42.9° 20:05	10.15	7%	82.6°
2037-02-18 Wed	80	—	unknown	19:35–23:20 (good, 3.75 h)	42.9° 20:00	10.11	12%	71.9°
2037-02-19 Thu	73	—	unknown	19:35–23:15 (good, 3.67 h)	42.9° 20:00	10.07	19%	61.2°
2037-02-20 Fri	62	—	unknown	19:35–23:15 (good, 3.67 h)	42.9° 19:55	10.03	27%	50.7°
2037-02-21 Sat	49	—	unknown	19:35–22:50 (good, 3.25 h)	42.9° 19:50	9.98	36%	40.7°
2037-02-22 Sun	36	—	unknown	20:25–21:35 (good, 1.17 h)	42.9° 19:45	9.94	46%	31.9°
2037-02-23 Mon	26	—	unknown	19:40–23:25 (marginal, 3.75 h)	42.9° 19:40	9.9	57%	26.0°
2037-02-24 Tue	18	—	unknown	19:40–23:05 (marginal, 3.42 h)	42.9° 19:40	9.86	68%	25.6°
2037-02-25 Wed	13	—	unknown	19:40–22:40 (marginal, 3.0 h)	42.9° 19:35	9.81	78%	31.5°
2037-02-26 Thu	12	—	unknown	19:45–22:25 (marginal, 2.67 h)	42.9° 19:30	9.77	86%	41.5°
2037-02-27 Fri	15	—	unknown	19:45–22:30 (marginal, 2.75 h)	42.9° 19:25	9.72	94%	53.6°
2037-02-28 Sat	21	—	unknown	19:45–22:45 (marginal, 3.0 h)	42.9° 19:25	9.68	98%	66.8°
2037-03-01 Sun	30	—	unknown	19:45–20:10 (good, 0.42 h)	42.9° 19:20	9.63	100%	80.5°
2037-03-02 Mon	38	—	unknown	19:50–21:55 (good, 2.08 h)	42.9° 19:15	9.59	99%	94.3°
2037-03-03 Tue	54	—	unknown	19:50–22:10 (good, 2.33 h)	42.9° 19:10	9.54	94%	107.9°
2037-03-04 Wed	57	—	unknown	19:50–22:20 (good, 2.5 h)	42.9° 19:05	9.49	88%	121.0°
2037-03-05 Thu	58	—	unknown	19:50–22:20 (good, 2.5 h)	42.9° 19:05	9.45	79%	133.1°
2037-03-06 Fri	56	—	unknown	19:50–22:20 (good, 2.5 h)	42.9° 19:00	9.4	69%	143.7°
2037-03-07 Sat	54	—	unknown	19:55–22:15 (good, 2.33 h)	42.9° 18:55	9.35	59%	151.6°
2037-03-08 Sun	52	—	unknown	19:55–22:10 (good, 2.25 h)	42.9° 18:50	9.3	49%	155.0°
2037-03-09 Mon	50	—	unknown	19:55–22:05 (good, 2.17 h)	42.9° 18:45	9.26	39%	152.6°
2037-03-10 Tue	49	—	unknown	19:55–22:00 (good, 2.08 h)	42.9° 18:45	9.21	29%	146.0°
2037-03-11 Wed	47	—	unknown	20:00–22:00 (good, 2.0 h)	42.9° 18:40	9.16	21%	137.3°
2037-03-12 Thu	45	—	unknown	20:00–21:55 (good, 1.92 h)	42.9° 18:35	9.11	14%	127.5°
2037-03-13 Fri	43	—	unknown	20:00–21:50 (good, 1.83 h)	42.9° 18:30	9.06	8%	117.3°
2037-03-14 Sat	42	—	unknown	20:00–21:45 (good, 1.75 h)	42.9° 18:30	9.01	4%	106.8°
2037-03-15 Sun	40	—	unknown	20:05–21:45 (good, 1.67 h)	42.9° 18:25	8.96	1%	96.1°
2037-03-16 Mon	38	—	unknown	20:05–21:40 (good, 1.58 h)	42.9° 18:20	8.91	0%	85.4°
2037-03-17 Tue	36	—	unknown	20:05–21:35 (good, 1.5 h)	42.9° 18:15	8.86	1%	74.6°
2037-03-18 Wed	35	—	unknown	20:05–21:30 (good, 1.42 h)	42.9° 18:10	8.81	4%	63.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-02-17&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.