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 Vega: 04-09 (100), 04-10 (100), 04-23 (100), 04-24 (100), 04-25 (100) — by astronomy; check the weather when the night is within four days.

2041-04-09astronomy score per night — click a bar for that night2041-05-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-04-09 Tue	100	—	unknown	01:00–05:15 (good, 4.25 h)	87.1° 06:45	7.62	64%	111.0°
2041-04-10 Wed	100	—	unknown	01:00–05:10 (good, 4.17 h)	87.1° 06:40	7.56	73%	108.2°
2041-04-11 Thu	89	—	unknown	01:05–05:10 (good, 4.08 h)	87.1° 06:35	7.5	81%	104.6°
2041-04-12 Fri	82	—	unknown	01:05–05:05 (good, 4.0 h)	87.1° 06:35	7.44	88%	100.5°
2041-04-13 Sat	74	—	unknown	01:20–05:05 (good, 3.75 h)	87.1° 06:30	7.39	94%	95.9°
2041-04-14 Sun	68	—	unknown	01:50–05:05 (good, 3.25 h)	87.1° 06:25	7.33	98%	91.0°
2041-04-15 Mon	61	—	unknown	02:15–05:00 (good, 2.75 h)	87.1° 06:20	7.27	100%	85.9°
2041-04-16 Tue	57	—	unknown	02:30–05:00 (good, 2.5 h)	87.1° 06:15	7.21	100%	81.0°
2041-04-17 Wed	55	—	unknown	02:30–04:55 (good, 2.42 h)	87.1° 06:15	7.16	98%	76.4°
2041-04-18 Thu	56	—	unknown	02:10–04:55 (good, 2.75 h)	87.1° 06:10	7.1	94%	72.3°
2041-04-19 Fri	60	—	unknown	00:55–04:55 (good, 4.0 h)	87.1° 06:05	7.04	88%	69.1°
2041-04-20 Sat	79	—	unknown	00:05–04:50 (good, 4.75 h)	87.1° 06:00	6.98	79%	66.9°
2041-04-21 Sun	90	—	unknown	00:05–04:50 (good, 4.75 h)	87.1° 05:55	6.92	70%	66.2°
2041-04-22 Mon	97	—	unknown	00:00–04:50 (good, 4.83 h)	87.1° 05:55	6.87	59%	66.8°
2041-04-23 Tue	100	—	unknown	23:55–04:45 (good, 4.83 h)	87.1° 05:50	6.81	48%	69.0°
2041-04-24 Wed	100	—	unknown	23:50–04:45 (good, 4.92 h)	87.1° 05:45	6.75	36%	72.4°
2041-04-25 Thu	100	—	unknown	23:45–04:40 (good, 4.92 h)	87.1° 05:40	6.69	26%	76.9°
2041-04-26 Fri	100	—	unknown	23:45–04:40 (good, 4.92 h)	87.1° 05:40	6.63	16%	82.2°
2041-04-27 Sat	100	—	unknown	23:40–04:40 (good, 5.0 h)	87.1° 05:35	6.57	8%	87.8°
2041-04-28 Sun	100	—	unknown	23:35–04:35 (good, 5.0 h)	87.1° 05:30	6.52	3%	93.6°
2041-04-29 Mon	100	—	unknown	23:30–04:35 (good, 5.08 h)	87.1° 05:25	6.46	0%	99.1°
2041-04-30 Tue	100	—	unknown	23:25–04:30 (good, 5.08 h)	87.1° 05:20	6.4	0%	104.1°
2041-05-01 Wed	100	—	unknown	23:25–04:30 (good, 5.08 h)	87.1° 05:20	6.34	2%	108.2°
2041-05-02 Thu	100	—	unknown	23:20–04:30 (good, 5.17 h)	87.1° 05:15	6.28	7%	111.3°
2041-05-03 Fri	100	—	unknown	23:15–04:25 (good, 5.17 h)	87.1° 05:10	6.23	13%	113.2°
2041-05-04 Sat	100	—	unknown	23:15–04:25 (good, 5.17 h)	87.1° 05:05	6.17	21%	113.8°
2041-05-05 Sun	100	—	unknown	23:10–04:25 (good, 5.25 h)	87.1° 05:00	6.11	29%	113.3°
2041-05-06 Mon	100	—	unknown	23:10–04:20 (good, 5.17 h)	87.1° 05:00	6.05	38%	111.7°
2041-05-07 Tue	100	—	unknown	23:10–04:20 (good, 5.17 h)	87.1° 04:55	6.0	48%	109.2°
2041-05-08 Wed	100	—	unknown	23:10–04:20 (good, 5.17 h)	87.1° 04:50	5.94	57%	105.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-04-09&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.