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: 06-17 (100), 06-18 (100), 06-19 (100), 06-20 (100), 06-21 (100) — by astronomy; check the weather when the night is within four days.

2031-06-17astronomy score per night — click a bar for that night2031-07-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-06-17 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:40	4.44	4%	109.3°
2031-06-18 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:35	4.43	1%	118.3°
2031-06-19 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 03:30	4.43	0%	126.6°
2031-06-20 Fri	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:25	4.42	1%	133.7°
2031-06-21 Sat	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:25	4.42	4%	139.3°
2031-06-22 Sun	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:20	4.42	8%	142.3°
2031-06-23 Mon	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:15	4.43	14%	142.4°
2031-06-24 Tue	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:10	4.43	21%	139.3°
2031-06-25 Wed	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:05	4.44	30%	133.6°
2031-06-26 Thu	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:05	4.45	39%	126.1°
2031-06-27 Fri	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 03:00	4.46	49%	117.2°
2031-06-28 Sat	100	—	unknown	23:15–03:40 (good, 4.42 h)	71.1° 02:55	4.48	60%	107.4°
2031-06-29 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	71.1° 02:50	4.5	70%	96.8°
2031-06-30 Mon	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:50	4.51	80%	85.8°
2031-07-01 Tue	100	—	unknown	23:10–03:45 (good, 4.58 h)	71.1° 02:45	4.53	88%	74.4°
2031-07-02 Wed	64	—	unknown	00:25–03:45 (good, 3.33 h)	71.1° 02:40	4.56	95%	63.2°
2031-07-03 Thu	47	—	unknown	03:30–03:45 (good, 0.25 h)	71.1° 02:35	4.58	99%	52.7°
2031-07-04 Fri	36	—	unknown	23:10–03:45 (marginal, 4.58 h)	71.1° 02:30	4.6	100%	43.9°
2031-07-05 Sat	32	—	unknown	23:10–03:45 (marginal, 4.58 h)	71.1° 02:30	4.63	98%	38.4°
2031-07-06 Sun	38	—	unknown	23:10–03:50 (marginal, 4.67 h)	71.1° 02:25	4.66	93%	37.6°
2031-07-07 Mon	50	—	unknown	23:10–00:20 (good, 1.17 h)	71.1° 02:20	4.69	86%	41.6°
2031-07-08 Tue	88	—	unknown	23:05–02:45 (good, 3.67 h)	71.1° 02:15	4.72	77%	48.9°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-06-17&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.