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: 09-09 (100), 09-10 (100), 09-11 (100), 09-12 (100), 09-13 (100) — by astronomy; check the weather when the night is within four days.

2042-09-09astronomy score per night — click a bar for that night2042-10-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-09-09 Tue	100	—	unknown	21:20–03:15 (good, 5.92 h)	71.1° 22:10	8.06	18%	131.4°
2042-09-10 Wed	100	—	unknown	21:15–03:10 (good, 5.92 h)	71.1° 22:05	8.11	11%	133.0°
2042-09-11 Thu	100	—	unknown	21:15–03:05 (good, 5.83 h)	71.1° 22:00	8.17	6%	131.9°
2042-09-12 Fri	100	—	unknown	21:15–03:00 (good, 5.75 h)	71.1° 21:55	8.22	2%	128.7°
2042-09-13 Sat	100	—	unknown	21:10–03:00 (good, 5.83 h)	71.1° 21:50	8.27	0%	123.6°
2042-09-14 Sun	100	—	unknown	21:10–02:55 (good, 5.75 h)	71.1° 21:50	8.33	0%	117.3°
2042-09-15 Mon	100	—	unknown	21:05–02:50 (good, 5.75 h)	71.1° 21:45	8.38	2%	110.2°
2042-09-16 Tue	100	—	unknown	21:05–02:45 (good, 5.67 h)	71.1° 21:40	8.43	6%	102.6°
2042-09-17 Wed	100	—	unknown	21:05–02:45 (good, 5.67 h)	71.1° 21:35	8.48	11%	94.6°
2042-09-18 Thu	100	—	unknown	21:00–02:40 (good, 5.67 h)	71.1° 21:30	8.54	18%	86.6°
2042-09-19 Fri	100	—	unknown	21:00–02:35 (good, 5.58 h)	71.1° 21:30	8.59	25%	78.6°
2042-09-20 Sat	100	—	unknown	21:00–02:30 (good, 5.5 h)	71.1° 21:25	8.64	34%	70.7°
2042-09-21 Sun	100	—	unknown	20:55–02:25 (good, 5.5 h)	71.1° 21:20	8.69	44%	63.3°
2042-09-22 Mon	98	—	unknown	20:55–02:25 (good, 5.5 h)	71.1° 21:15	8.74	54%	56.7°
2042-09-23 Tue	90	—	unknown	20:50–02:20 (good, 5.5 h)	71.1° 21:15	8.79	64%	51.3°
2042-09-24 Wed	81	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:10	8.84	74%	47.9°
2042-09-25 Thu	52	—	unknown	20:50–21:25 (good, 0.58 h)	71.1° 21:05	8.89	83%	47.2°
2042-09-26 Fri	46	—	unknown	20:45–02:20 (marginal, 5.58 h)	71.1° 21:00	8.94	91%	49.7°
2042-09-27 Sat	44	—	unknown	20:45–02:10 (marginal, 5.42 h)	71.1° 20:55	8.99	96%	55.1°
2042-09-28 Sun	47	—	unknown	20:45–21:20 (good, 0.58 h)	71.1° 20:55	9.04	100%	62.8°
2042-09-29 Mon	56	—	unknown	20:40–22:45 (good, 2.08 h)	71.1° 20:50	9.09	100%	72.0°
2042-09-30 Tue	69	—	unknown	20:40–23:45 (good, 3.08 h)	71.1° 20:45	9.14	97%	82.1°
2042-10-01 Wed	82	—	unknown	20:40–00:50 (good, 4.17 h)	71.1° 20:40	9.19	91%	92.3°
2042-10-02 Thu	100	—	unknown	20:35–01:20 (good, 4.75 h)	71.1° 20:35	9.23	83%	102.2°
2042-10-03 Fri	100	—	unknown	20:35–01:25 (good, 4.83 h)	71.1° 20:35	9.28	73%	111.4°
2042-10-04 Sat	100	—	unknown	20:35–01:30 (good, 4.92 h)	71.1° 20:30	9.33	63%	119.5°
2042-10-05 Sun	100	—	unknown	20:30–01:25 (good, 4.92 h)	71.1° 20:25	9.38	52%	126.1°
2042-10-06 Mon	100	—	unknown	20:30–01:25 (good, 4.92 h)	71.1° 20:20	9.42	41%	130.6°
2042-10-07 Tue	100	—	unknown	20:25–01:25 (good, 5.0 h)	71.1° 20:20	9.47	32%	132.8°
2042-10-08 Wed	100	—	unknown	20:25–01:20 (good, 4.92 h)	71.1° 20:15	9.51	23%	132.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-09-09&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.