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 Andromeda Galaxy: 02-17 (48), 02-18 (45), 02-19 (43), 02-20 (41), 02-21 (40) — by astronomy; check the weather when the night is within four days.

2039-02-17astronomy score per night — click a bar for that night2039-03-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-02-17 Thu	48	—	unknown	19:30–21:25 (good, 1.92 h)	89.7° 15:15	10.17	30%	118.1°
2039-02-18 Fri	45	—	unknown	19:35–21:20 (good, 1.75 h)	89.5° 15:10	10.13	20%	107.7°
2039-02-19 Sat	43	—	unknown	19:35–21:15 (good, 1.67 h)	89.7° 15:10	10.09	12%	96.8°
2039-02-20 Sun	41	—	unknown	19:35–21:15 (good, 1.67 h)	89.8° 15:05	10.05	6%	85.9°
2039-02-21 Mon	40	—	unknown	19:35–21:10 (good, 1.58 h)	89.8° 15:00	10.01	2%	75.3°
2039-02-22 Tue	37	—	unknown	19:40–21:05 (good, 1.42 h)	89.6° 14:55	9.96	0%	65.1°
2039-02-23 Wed	35	—	unknown	19:40–21:00 (good, 1.33 h)	89.5° 14:55	9.92	1%	55.8°
2039-02-24 Thu	33	—	unknown	19:40–21:00 (good, 1.33 h)	89.7° 14:50	9.88	4%	47.8°
2039-02-25 Fri	30	—	unknown	19:40–20:55 (good, 1.25 h)	89.8° 14:45	9.83	8%	41.7°
2039-02-26 Sat	27	—	unknown	19:40–20:45 (good, 1.08 h)	89.7° 14:40	9.79	14%	38.2°
2039-02-27 Sun	22	—	unknown	19:45–20:35 (good, 0.83 h)	89.6° 14:35	9.74	22%	38.0°
2039-02-28 Mon	18	—	unknown	19:45–20:20 (good, 0.58 h)	89.6° 14:35	9.7	30%	40.9°
2039-03-01 Tue	15	—	unknown	19:45–20:10 (good, 0.42 h)	89.7° 14:30	9.65	39%	46.2°
2039-03-02 Wed	12	—	unknown	19:45–21:05 (marginal, 1.33 h)	89.8° 14:25	9.61	48%	53.2°
2039-03-03 Thu	10	—	unknown	19:50–21:00 (marginal, 1.17 h)	89.7° 14:20	9.56	58%	61.3°
2039-03-04 Fri	9	—	unknown	19:50–20:50 (marginal, 1.0 h)	89.5° 14:15	9.52	67%	70.3°
2039-03-05 Sat	8	—	unknown	19:50–20:45 (marginal, 0.92 h)	89.6° 14:15	9.47	76%	79.8°
2039-03-06 Sun	8	—	unknown	19:50–20:45 (marginal, 0.92 h)	89.8° 14:10	9.42	84%	89.7°
2039-03-07 Mon	8	—	unknown	19:55–20:45 (marginal, 0.83 h)	89.8° 14:05	9.38	91%	100.0°
2039-03-08 Tue	8	—	unknown	19:55–20:45 (marginal, 0.83 h)	89.6° 14:00	9.33	96%	110.3°
2039-03-09 Wed	8	—	unknown	19:25–20:40 (marginal, 1.25 h)	89.5° 14:00	9.28	99%	120.4°
2039-03-10 Thu	8	—	unknown	19:55–20:35 (marginal, 0.67 h)	89.7° 13:55	9.23	100%	129.7°
2039-03-11 Fri	6	—	unknown	20:00–20:30 (marginal, 0.5 h)	89.8° 13:50	9.18	98%	137.3°
2039-03-12 Sat	7	—	unknown	20:00–20:30 (marginal, 0.5 h)	89.7° 13:45	9.13	93%	141.8°
2039-03-13 Sun	6	—	unknown	20:00–20:25 (marginal, 0.42 h)	89.6° 13:40	9.08	86%	141.8°
2039-03-14 Mon	5	—	unknown	20:00–20:20 (marginal, 0.33 h)	89.6° 13:40	9.03	77%	137.5°
2039-03-15 Tue	3	—	unknown	19:30–19:45 (marginal, 0.25 h)	89.7° 13:35	8.98	67%	129.9°
2039-03-16 Wed	3	—	unknown	19:30–19:40 (marginal, 0.17 h)	89.8° 13:30	8.93	56%	120.6°
2039-03-17 Thu	2	—	unknown	20:05–20:10 (marginal, 0.08 h)	89.7° 13:25	8.88	44%	110.3°
2039-03-18 Fri	1	—	unknown	—	89.5° 13:20	8.83	33%	99.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-02-17&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.