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: 07-21 (100), 07-22 (100), 07-23 (100), 07-24 (100), 07-25 (100) — by astronomy; check the weather when the night is within four days.

2031-07-21astronomy score per night — click a bar for that night2031-08-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-07-21 Mon	100	—	unknown	22:50–04:10 (good, 5.33 h)	87.1° 00:00	5.26	5%	116.1°
2031-07-22 Tue	100	—	unknown	22:50–04:10 (good, 5.33 h)	87.1° 23:55	5.31	10%	111.6°
2031-07-23 Wed	100	—	unknown	22:50–04:10 (good, 5.33 h)	87.1° 23:55	5.36	17%	106.1°
2031-07-24 Thu	100	—	unknown	22:50–04:15 (good, 5.42 h)	87.1° 23:50	5.41	25%	99.9°
2031-07-25 Fri	100	—	unknown	22:45–04:15 (good, 5.5 h)	87.1° 23:45	5.46	34%	93.3°
2031-07-26 Sat	100	—	unknown	22:45–04:15 (good, 5.5 h)	87.1° 23:40	5.51	45%	86.3°
2031-07-27 Sun	100	—	unknown	22:45–04:15 (good, 5.5 h)	87.1° 23:40	5.57	55%	79.4°
2031-07-28 Mon	100	—	unknown	22:40–04:20 (good, 5.67 h)	87.1° 23:35	5.62	66%	72.6°
2031-07-29 Tue	100	—	unknown	22:40–04:20 (good, 5.67 h)	87.1° 23:30	5.67	77%	66.5°
2031-07-30 Wed	93	—	unknown	22:40–04:20 (good, 5.67 h)	87.1° 23:25	5.73	86%	61.6°
2031-07-31 Thu	84	—	unknown	00:15–04:25 (good, 4.17 h)	87.1° 23:20	5.78	93%	58.5°
2031-08-01 Fri	54	—	unknown	22:35–04:25 (marginal, 5.83 h)	87.1° 23:20	5.84	98%	57.8°
2031-08-02 Sat	53	—	unknown	22:35–04:25 (marginal, 5.83 h)	87.1° 23:15	5.89	100%	59.5°
2031-08-03 Sun	59	—	unknown	22:30–23:25 (good, 0.92 h)	87.1° 23:10	5.95	99%	63.4°
2031-08-04 Mon	69	—	unknown	22:30–01:20 (good, 2.83 h)	87.1° 23:05	6.0	95%	69.0°
2031-08-05 Tue	76	—	unknown	22:30–02:35 (good, 4.08 h)	87.1° 23:00	6.06	88%	75.7°
2031-08-06 Wed	83	—	unknown	22:25–03:35 (good, 5.17 h)	87.1° 23:00	6.12	80%	82.8°
2031-08-07 Thu	100	—	unknown	22:25–04:25 (good, 6.0 h)	87.1° 22:55	6.17	71%	90.0°
2031-08-08 Fri	100	—	unknown	22:25–04:30 (good, 6.08 h)	87.1° 22:50	6.23	61%	96.9°
2031-08-09 Sat	100	—	unknown	22:20–04:35 (good, 6.25 h)	87.1° 22:45	6.29	51%	103.4°
2031-08-10 Sun	100	—	unknown	22:20–04:35 (good, 6.25 h)	87.1° 22:45	6.34	41%	109.3°
2031-08-11 Mon	100	—	unknown	22:15–04:35 (good, 6.33 h)	87.1° 22:40	6.4	32%	114.3°
2031-08-12 Tue	100	—	unknown	22:15–04:30 (good, 6.25 h)	87.1° 22:35	6.46	23%	118.2°
2031-08-13 Wed	100	—	unknown	22:15–04:30 (good, 6.25 h)	87.1° 22:30	6.52	16%	120.9°
2031-08-14 Thu	100	—	unknown	22:10–04:25 (good, 6.25 h)	87.1° 22:25	6.57	10%	122.2°
2031-08-15 Fri	100	—	unknown	22:10–04:20 (good, 6.17 h)	87.1° 22:25	6.63	5%	122.0°
2031-08-16 Sat	100	—	unknown	22:05–04:20 (good, 6.25 h)	87.1° 22:20	6.69	2%	120.2°
2031-08-17 Sun	100	—	unknown	22:05–04:15 (good, 6.17 h)	87.1° 22:15	6.75	0%	117.1°
2031-08-18 Mon	100	—	unknown	22:05–04:10 (good, 6.08 h)	87.1° 22:10	6.8	1%	112.7°
2031-08-19 Tue	100	—	unknown	22:00–04:05 (good, 6.08 h)	87.1° 22:05	6.86	3%	107.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-07-21&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.