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: 02-18 (84), 02-19 (82), 02-20 (80), 02-21 (80), 02-22 (77) — by astronomy; check the weather when the night is within four days.

2044-02-18astronomy score per night — click a bar for that night2044-03-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-02-18 Thu	84	—	unknown	19:35–23:25 (good, 3.83 h)	42.9° 20:05	10.14	68%	126.5°
2044-02-19 Fri	82	—	unknown	19:35–23:20 (good, 3.75 h)	42.9° 20:00	10.1	59%	134.7°
2044-02-20 Sat	80	—	unknown	19:35–23:15 (good, 3.67 h)	42.9° 19:55	10.06	49%	141.2°
2044-02-21 Sun	80	—	unknown	19:35–23:10 (good, 3.58 h)	42.9° 19:55	10.01	40%	145.2°
2044-02-22 Mon	77	—	unknown	19:40–23:10 (good, 3.5 h)	42.9° 19:50	9.97	31%	145.9°
2044-02-23 Tue	76	—	unknown	19:40–23:05 (good, 3.42 h)	42.9° 19:45	9.93	22%	143.1°
2044-02-24 Wed	74	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:40	9.89	15%	137.4°
2044-02-25 Thu	73	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:40	9.84	9%	129.7°
2044-02-26 Fri	71	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:35	9.8	4%	120.6°
2044-02-27 Sat	69	—	unknown	19:45–22:50 (good, 3.08 h)	42.9° 19:30	9.75	1%	110.6°
2044-02-28 Sun	67	—	unknown	19:45–22:45 (good, 3.0 h)	42.9° 19:25	9.71	0%	100.0°
2044-02-29 Mon	65	—	unknown	19:45–22:40 (good, 2.92 h)	42.9° 19:20	9.66	1%	88.9°
2044-03-01 Tue	64	—	unknown	19:45–22:35 (good, 2.83 h)	42.9° 19:20	9.62	5%	77.8°
2044-03-02 Wed	59	—	unknown	19:50–22:35 (good, 2.75 h)	42.9° 19:15	9.57	11%	66.7°
2044-03-03 Thu	52	—	unknown	19:50–22:25 (good, 2.58 h)	42.9° 19:10	9.53	19%	56.0°
2044-03-04 Fri	42	—	unknown	19:50–22:10 (good, 2.33 h)	42.9° 19:05	9.48	28%	46.3°
2044-03-05 Sat	32	—	unknown	19:50–21:55 (good, 2.08 h)	42.9° 19:00	9.43	39%	38.6°
2044-03-06 Sun	23	—	unknown	19:55–22:45 (marginal, 2.83 h)	42.9° 19:00	9.38	51%	34.3°
2044-03-07 Mon	16	—	unknown	19:55–22:25 (marginal, 2.5 h)	42.9° 18:55	9.34	62%	34.9°
2044-03-08 Tue	12	—	unknown	19:55–22:10 (marginal, 2.25 h)	42.9° 18:50	9.29	73%	40.1°
2044-03-09 Wed	11	—	unknown	19:55–22:00 (marginal, 2.08 h)	42.9° 18:45	9.24	82%	48.5°
2044-03-10 Thu	12	—	unknown	19:55–22:00 (marginal, 2.08 h)	42.9° 18:40	9.19	90%	58.6°
2044-03-11 Fri	15	—	unknown	20:00–22:05 (marginal, 2.08 h)	42.9° 18:40	9.14	96%	69.5°
2044-03-12 Sat	20	—	unknown	20:00–22:10 (marginal, 2.17 h)	42.9° 18:35	9.09	99%	80.7°
2044-03-13 Sun	24	—	unknown	20:00–21:00 (good, 1.0 h)	42.9° 18:30	9.04	100%	91.9°
2044-03-14 Mon	29	—	unknown	20:00–21:25 (good, 1.42 h)	42.9° 18:25	8.99	99%	102.9°
2044-03-15 Tue	37	—	unknown	20:05–21:30 (good, 1.42 h)	42.9° 18:25	8.94	95%	113.3°
2044-03-16 Wed	38	—	unknown	20:05–21:40 (good, 1.58 h)	42.9° 18:20	8.89	90%	123.1°
2044-03-17 Thu	36	—	unknown	20:05–21:35 (good, 1.5 h)	42.9° 18:15	8.84	83%	131.8°
2044-03-18 Fri	35	—	unknown	20:05–21:30 (good, 1.42 h)	42.9° 18:10	8.79	75%	139.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-02-18&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.