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 HD 189733: 07-10 (100), 07-11 (100), 07-12 (100), 07-13 (100), 07-14 (100) — by astronomy; check the weather when the night is within four days.

2031-07-09astronomy score per night — click a bar for that night2031-08-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-07-09 Wed	96	—	unknown	23:05–03:50 (good, 4.75 h)	71.1° 02:10	4.76	66%	57.9°
2031-07-10 Thu	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:10	4.79	56%	67.7°
2031-07-11 Fri	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:05	4.83	45%	77.8°
2031-07-12 Sat	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:00	4.87	36%	87.8°
2031-07-13 Sun	100	—	unknown	23:00–03:55 (good, 4.92 h)	71.1° 01:55	4.91	26%	97.6°
2031-07-14 Mon	100	—	unknown	23:00–04:00 (good, 5.0 h)	71.1° 01:55	4.95	18%	107.1°
2031-07-15 Tue	100	—	unknown	23:00–04:00 (good, 5.0 h)	71.1° 01:50	4.99	12%	116.2°
2031-07-16 Wed	100	—	unknown	23:00–04:00 (good, 5.0 h)	71.1° 01:45	5.03	6%	124.7°
2031-07-17 Thu	100	—	unknown	23:00–04:00 (good, 5.0 h)	71.1° 01:40	5.08	2%	132.1°
2031-07-18 Fri	100	—	unknown	22:55–04:05 (good, 5.17 h)	71.1° 01:35	5.12	0%	138.1°
2031-07-19 Sat	100	—	unknown	22:55–04:05 (good, 5.17 h)	71.1° 01:35	5.17	0%	141.8°
2031-07-20 Sun	100	—	unknown	22:55–04:05 (good, 5.17 h)	71.1° 01:30	5.21	2%	142.6°
2031-07-21 Mon	100	—	unknown	22:50–04:10 (good, 5.33 h)	71.1° 01:25	5.26	5%	140.2°
2031-07-22 Tue	100	—	unknown	22:50–04:10 (good, 5.33 h)	71.1° 01:20	5.31	10%	135.0°
2031-07-23 Wed	100	—	unknown	22:50–04:10 (good, 5.33 h)	71.1° 01:15	5.36	17%	127.9°
2031-07-24 Thu	100	—	unknown	22:50–04:15 (good, 5.42 h)	71.1° 01:15	5.41	25%	119.4°
2031-07-25 Fri	100	—	unknown	22:45–04:15 (good, 5.5 h)	71.1° 01:10	5.46	34%	110.0°
2031-07-26 Sat	100	—	unknown	22:45–04:15 (good, 5.5 h)	71.1° 01:05	5.51	45%	99.9°
2031-07-27 Sun	100	—	unknown	22:45–04:15 (good, 5.5 h)	71.1° 01:00	5.57	55%	89.3°
2031-07-28 Mon	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 01:00	5.62	66%	78.4°
2031-07-29 Tue	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 00:55	5.67	77%	67.4°
2031-07-30 Wed	98	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 00:50	5.73	86%	56.9°
2031-07-31 Thu	89	—	unknown	02:15–04:25 (good, 2.17 h)	71.1° 00:45	5.78	93%	47.4°
2031-08-01 Fri	42	—	unknown	22:35–04:25 (marginal, 5.83 h)	71.1° 00:40	5.84	98%	40.3°
2031-08-02 Sat	35	—	unknown	22:35–04:25 (marginal, 5.83 h)	71.1° 00:40	5.89	100%	37.4°
2031-08-03 Sun	38	—	unknown	22:30–04:30 (marginal, 6.0 h)	71.1° 00:35	5.95	99%	39.4°
2031-08-04 Mon	49	—	unknown	22:30–04:30 (marginal, 6.0 h)	71.1° 00:30	6.0	95%	45.7°
2031-08-05 Tue	66	—	unknown	22:30–00:20 (good, 1.83 h)	71.1° 00:25	6.06	88%	54.5°
2031-08-06 Wed	77	—	unknown	22:25–02:45 (good, 4.33 h)	71.1° 00:20	6.12	80%	64.4°
2031-08-07 Thu	100	—	unknown	22:25–04:05 (good, 5.67 h)	71.1° 00:20	6.17	71%	74.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-07-09&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.