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: 03-12 (7), 03-13 (6), 03-14 (5), 03-15 (3), 03-16 (3) — by astronomy; check the weather when the night is within four days.

2039-03-12astronomy score per night — click a bar for that night2039-04-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2039-03-19 Sat	1	—	unknown	—	89.6° 13:20	8.78	24%	88.8°
2039-03-20 Sun	1	—	unknown	—	89.8° 13:15	8.73	15%	78.3°
2039-03-21 Mon	1	—	unknown	—	89.8° 13:10	8.68	8%	68.1°
2039-03-22 Tue	0	—	unknown	—	89.6° 13:05	8.63	4%	58.6°
2039-03-23 Wed	0	—	unknown	—	89.5° 13:05	8.57	1%	50.2°
2039-03-24 Thu	0	—	unknown	—	89.7° 13:00	8.52	0%	43.4°
2039-03-25 Fri	0	—	unknown	—	89.8° 12:55	8.47	2%	38.9°
2039-03-26 Sat	0	—	unknown	—	89.7° 12:50	8.42	5%	37.6°
2039-03-27 Sun	0	—	unknown	—	89.6° 13:45	8.36	10%	39.4°
2039-03-28 Mon	0	—	unknown	—	89.6° 13:45	8.31	16%	44.0°
2039-03-29 Tue	0	—	unknown	—	89.7° 13:40	8.25	23%	50.6°
2039-03-30 Wed	0	—	unknown	—	89.8° 13:35	8.2	32%	58.4°
2039-03-31 Thu	0	—	unknown	—	89.7° 13:30	8.15	41%	67.0°
2039-04-01 Fri	0	—	unknown	—	89.5° 13:25	8.09	50%	76.2°
2039-04-02 Sat	0	—	unknown	—	89.6° 13:25	8.04	60%	85.8°
2039-04-03 Sun	0	—	unknown	—	89.8° 13:20	7.98	70%	95.8°
2039-04-04 Mon	0	—	unknown	—	89.8° 13:15	7.93	79%	106.0°
2039-04-05 Tue	0	—	unknown	—	89.6° 13:10	7.87	87%	116.1°
2039-04-06 Wed	0	—	unknown	—	89.5° 13:10	7.81	93%	125.8°
2039-04-07 Thu	0	—	unknown	—	89.7° 13:05	7.76	98%	134.3°
2039-04-08 Fri	0	—	unknown	—	89.8° 13:00	7.7	100%	140.4°
2039-04-09 Sat	0	—	unknown	—	89.7° 12:55	7.64	99%	142.5°
2039-04-10 Sun	0	—	unknown	—	89.6° 12:50	7.59	95%	139.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-03-12&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.