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: 02-12 (89), 02-13 (89), 02-14 (89), 02-15 (88), 02-16 (87) — by astronomy; check the weather when the night is within four days.

2039-02-04astronomy score per night — click a bar for that night2039-03-05

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-02-04 Fri	15	—	unknown	19:15–00:00 (marginal, 4.75 h)	42.9° 21:00	10.66	83%	28.6°
2039-02-05 Sat	13	—	unknown	19:20–20:20 (marginal, 1.0 h)	42.9° 20:55	10.63	89%	33.2°
2039-02-06 Sun	15	—	unknown	19:20–21:40 (marginal, 2.33 h)	42.9° 20:50	10.59	95%	40.9°
2039-02-07 Mon	20	—	unknown	19:20–23:35 (marginal, 4.25 h)	42.9° 20:45	10.56	98%	50.6°
2039-02-08 Tue	30	—	unknown	19:20–23:50 (marginal, 4.5 h)	42.9° 20:45	10.52	100%	61.5°
2039-02-09 Wed	42	—	unknown	19:25–19:50 (good, 0.42 h)	42.9° 20:40	10.48	99%	73.0°
2039-02-10 Thu	56	—	unknown	19:25–22:15 (good, 2.83 h)	42.9° 20:35	10.45	96%	85.0°
2039-02-11 Fri	82	—	unknown	19:25–23:25 (good, 4.0 h)	42.9° 20:30	10.41	91%	97.2°
2039-02-12 Sat	89	—	unknown	19:25–23:30 (good, 4.08 h)	42.9° 20:30	10.37	83%	109.5°
2039-02-13 Sun	89	—	unknown	19:25–23:35 (good, 4.17 h)	42.9° 20:25	10.33	74%	121.5°
2039-02-14 Mon	89	—	unknown	19:30–23:40 (good, 4.17 h)	42.9° 20:20	10.29	63%	132.9°
2039-02-15 Tue	88	—	unknown	19:30–23:35 (good, 4.08 h)	42.9° 20:15	10.25	52%	142.9°
2039-02-16 Wed	87	—	unknown	19:30–23:30 (good, 4.0 h)	42.9° 20:10	10.21	41%	150.0°
2039-02-17 Thu	86	—	unknown	19:30–23:25 (good, 3.92 h)	42.9° 20:10	10.17	30%	151.9°
2039-02-18 Fri	84	—	unknown	19:35–23:25 (good, 3.83 h)	42.9° 20:05	10.13	20%	147.7°
2039-02-19 Sat	82	—	unknown	19:35–23:20 (good, 3.75 h)	42.9° 20:00	10.09	12%	139.4°
2039-02-20 Sun	80	—	unknown	19:35–23:15 (good, 3.67 h)	42.9° 19:55	10.05	6%	129.0°
2039-02-21 Mon	79	—	unknown	19:35–23:10 (good, 3.58 h)	42.9° 19:50	10.01	2%	117.8°
2039-02-22 Tue	77	—	unknown	19:40–23:05 (good, 3.42 h)	42.9° 19:50	9.96	0%	106.2°
2039-02-23 Wed	75	—	unknown	19:40–23:05 (good, 3.42 h)	42.9° 19:45	9.92	1%	94.7°
2039-02-24 Thu	73	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:40	9.88	4%	83.4°
2039-02-25 Fri	71	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:35	9.83	8%	72.3°
2039-02-26 Sat	65	—	unknown	19:40–22:50 (good, 3.17 h)	42.9° 19:35	9.79	14%	61.7°
2039-02-27 Sun	57	—	unknown	19:45–22:50 (good, 3.08 h)	42.9° 19:30	9.74	22%	51.8°
2039-02-28 Mon	47	—	unknown	19:45–22:30 (good, 2.75 h)	42.9° 19:25	9.7	30%	42.6°
2039-03-01 Tue	37	—	unknown	19:45–22:15 (good, 2.5 h)	42.9° 19:20	9.65	39%	34.9°
2039-03-02 Wed	27	—	unknown	19:45–23:05 (marginal, 3.33 h)	42.9° 19:15	9.61	48%	29.6°
2039-03-03 Thu	20	—	unknown	19:50–22:50 (marginal, 3.0 h)	42.9° 19:15	9.56	58%	28.2°
2039-03-04 Fri	14	—	unknown	19:50–22:35 (marginal, 2.75 h)	42.9° 19:10	9.52	67%	31.2°
2039-03-05 Sat	12	—	unknown	19:50–22:15 (marginal, 2.42 h)	42.9° 19:05	9.47	76%	37.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-02-04&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.