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: 05-17 (100), 05-18 (100), 05-19 (100), 05-20 (100), 05-21 (100) — by astronomy; check the weather when the night is within four days.

2031-05-17astronomy score per night — click a bar for that night2031-06-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-05-17 Sat	100	—	unknown	22:35–04:05 (good, 5.5 h)	87.1° 04:15	5.48	11%	88.3°
2031-05-18 Sun	100	—	unknown	22:35–04:05 (good, 5.5 h)	87.1° 04:15	5.43	6%	95.1°
2031-05-19 Mon	100	—	unknown	22:40–04:00 (good, 5.33 h)	87.1° 04:10	5.38	2%	101.6°
2031-05-20 Tue	100	—	unknown	22:40–04:00 (good, 5.33 h)	87.1° 04:05	5.33	0%	107.6°
2031-05-21 Wed	100	—	unknown	22:40–04:00 (good, 5.33 h)	87.1° 04:00	5.28	0%	112.8°
2031-05-22 Thu	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:55	5.23	2%	117.2°
2031-05-23 Fri	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:55	5.18	6%	120.3°
2031-05-24 Sat	100	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:50	5.14	12%	122.0°
2031-05-25 Sun	100	—	unknown	22:50–03:55 (good, 5.08 h)	87.1° 03:45	5.09	18%	122.2°
2031-05-26 Mon	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:40	5.05	26%	120.9°
2031-05-27 Tue	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:40	5.0	35%	118.2°
2031-05-28 Wed	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:35	4.96	45%	114.2°
2031-05-29 Thu	100	—	unknown	22:55–03:50 (good, 4.92 h)	87.1° 03:30	4.92	55%	109.0°
2031-05-30 Fri	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:25	4.88	65%	103.0°
2031-05-31 Sat	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:20	4.84	74%	96.3°
2031-06-01 Sun	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:20	4.8	83%	89.1°
2031-06-02 Mon	80	—	unknown	23:00–03:45 (good, 4.75 h)	87.1° 03:15	4.77	91%	81.6°
2031-06-03 Tue	70	—	unknown	23:25–03:45 (good, 4.33 h)	87.1° 03:10	4.73	96%	74.4°
2031-06-04 Wed	59	—	unknown	00:05–03:45 (good, 3.67 h)	87.1° 03:05	4.7	100%	67.7°
2031-06-05 Thu	52	—	unknown	03:05–03:40 (good, 0.58 h)	87.1° 03:00	4.67	100%	62.4°
2031-06-06 Fri	53	—	unknown	23:05–01:05 (good, 2.0 h)	87.1° 03:00	4.64	97%	58.9°
2031-06-07 Sat	60	—	unknown	23:05–02:30 (good, 3.42 h)	87.1° 02:55	4.61	91%	57.7°
2031-06-08 Sun	95	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:50	4.59	83%	58.9°
2031-06-09 Mon	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:45	4.56	74%	62.3°
2031-06-10 Tue	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:45	4.54	63%	67.3°
2031-06-11 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:40	4.52	52%	73.3°
2031-06-12 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:35	4.5	41%	79.9°
2031-06-13 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:30	4.48	31%	86.7°
2031-06-14 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:25	4.47	22%	93.5°
2031-06-15 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:25	4.46	14%	100.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-05-17&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.