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: 02-27 (67), 02-28 (67), 02-26 (66), 03-01 (65), 03-02 (63) — by astronomy; check the weather when the night is within four days.

2043-02-23astronomy score per night — click a bar for that night2043-03-24

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-02-23 Mon	32	—	unknown	19:40–19:50 (good, 0.17 h)	42.9° 19:45	9.92	100%	76.1°
2043-02-24 Tue	41	—	unknown	19:40–21:30 (good, 1.83 h)	42.9° 19:40	9.88	99%	86.6°
2043-02-25 Wed	60	—	unknown	19:40–22:25 (good, 2.75 h)	42.9° 19:35	9.83	96%	96.9°
2043-02-26 Thu	66	—	unknown	19:40–22:35 (good, 2.92 h)	42.9° 19:35	9.79	91%	107.0°
2043-02-27 Fri	67	—	unknown	19:45–22:40 (good, 2.92 h)	42.9° 19:30	9.74	85%	116.6°
2043-02-28 Sat	67	—	unknown	19:45–22:45 (good, 3.0 h)	42.9° 19:25	9.7	78%	125.6°
2043-03-01 Sun	65	—	unknown	19:45–22:40 (good, 2.92 h)	42.9° 19:20	9.65	70%	133.8°
2043-03-02 Mon	63	—	unknown	19:45–22:35 (good, 2.83 h)	42.9° 19:15	9.61	60%	140.6°
2043-03-03 Tue	62	—	unknown	19:50–22:30 (good, 2.67 h)	42.9° 19:15	9.56	51%	145.0°
2043-03-04 Wed	60	—	unknown	19:50–22:30 (good, 2.67 h)	42.9° 19:10	9.51	41%	146.2°
2043-03-05 Thu	58	—	unknown	19:50–22:25 (good, 2.58 h)	42.9° 19:05	9.47	32%	143.7°
2043-03-06 Fri	57	—	unknown	19:50–22:20 (good, 2.5 h)	42.9° 19:00	9.42	23%	137.7°
2043-03-07 Sat	54	—	unknown	19:55–22:15 (good, 2.33 h)	42.9° 18:55	9.37	15%	129.4°
2043-03-08 Sun	53	—	unknown	19:55–22:10 (good, 2.25 h)	42.9° 18:55	9.33	8%	119.4°
2043-03-09 Mon	51	—	unknown	19:55–22:10 (good, 2.25 h)	42.9° 18:50	9.28	3%	108.4°
2043-03-10 Tue	50	—	unknown	19:55–22:05 (good, 2.17 h)	42.9° 18:45	9.23	0%	96.6°
2043-03-11 Wed	47	—	unknown	20:00–22:00 (good, 2.0 h)	42.9° 18:40	9.18	0%	84.5°
2043-03-12 Thu	46	—	unknown	20:00–21:55 (good, 1.92 h)	42.9° 18:40	9.13	3%	72.3°
2043-03-13 Fri	42	—	unknown	20:00–21:55 (good, 1.92 h)	42.9° 18:35	9.08	9%	60.5°
2043-03-14 Sat	36	—	unknown	20:00–21:40 (good, 1.67 h)	42.9° 18:30	9.03	17%	49.8°
2043-03-15 Sun	29	—	unknown	20:05–21:30 (good, 1.42 h)	42.9° 18:25	8.98	27%	40.8°
2043-03-16 Mon	22	—	unknown	20:05–21:10 (good, 1.08 h)	42.9° 18:20	8.93	38%	35.1°
2043-03-17 Tue	16	—	unknown	20:05–22:00 (marginal, 1.92 h)	42.9° 18:20	8.88	49%	33.9°
2043-03-18 Wed	12	—	unknown	20:05–21:50 (marginal, 1.75 h)	42.9° 18:15	8.83	60%	37.5°
2043-03-19 Thu	9	—	unknown	20:10–21:35 (marginal, 1.42 h)	42.9° 18:10	8.78	70%	44.5°
2043-03-20 Fri	8	—	unknown	20:10–21:25 (marginal, 1.25 h)	42.9° 18:05	8.73	79%	53.3°
2043-03-21 Sat	9	—	unknown	20:10–21:25 (marginal, 1.25 h)	42.9° 18:00	8.68	87%	63.0°
2043-03-22 Sun	10	—	unknown	20:10–21:30 (marginal, 1.33 h)	42.9° 18:00	8.62	93%	73.2°
2043-03-23 Mon	12	—	unknown	20:15–21:35 (marginal, 1.33 h)	42.9° 17:55	8.57	97%	83.5°
2043-03-24 Tue	14	—	unknown	20:15–20:30 (good, 0.25 h)	42.9° 17:50	8.52	100%	93.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-02-23&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.