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: 09-20 (100), 09-21 (100), 09-22 (100), 09-23 (100), 10-05 (100) — by astronomy; check the weather when the night is within four days.

2039-09-20astronomy score per night — click a bar for that night2039-10-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-09-20 Tue	100	—	unknown	21:00–02:30 (good, 5.5 h)	71.1° 21:25	8.62	8%	93.1°
2039-09-21 Wed	100	—	unknown	20:55–02:30 (good, 5.58 h)	71.1° 21:20	8.68	16%	83.2°
2039-09-22 Thu	100	—	unknown	20:55–02:25 (good, 5.5 h)	71.1° 21:20	8.73	25%	73.6°
2039-09-23 Fri	100	—	unknown	20:55–02:20 (good, 5.42 h)	71.1° 21:15	8.78	36%	64.6°
2039-09-24 Sat	98	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:10	8.83	47%	56.6°
2039-09-25 Sun	92	—	unknown	20:50–02:10 (good, 5.33 h)	71.1° 21:05	8.88	58%	50.5°
2039-09-26 Mon	83	—	unknown	20:45–02:10 (good, 5.42 h)	71.1° 21:00	8.93	69%	46.9°
2039-09-27 Tue	55	—	unknown	20:45–23:40 (good, 2.92 h)	71.1° 21:00	8.98	79%	46.3°
2039-09-28 Wed	48	—	unknown	20:45–02:20 (marginal, 5.58 h)	71.1° 20:55	9.03	87%	48.8°
2039-09-29 Thu	46	—	unknown	20:40–02:10 (marginal, 5.5 h)	71.1° 20:50	9.08	94%	53.9°
2039-09-30 Fri	48	—	unknown	20:40–21:15 (good, 0.58 h)	71.1° 20:45	9.12	98%	60.7°
2039-10-01 Sat	53	—	unknown	20:40–22:20 (good, 1.67 h)	71.1° 20:40	9.17	100%	68.6°
2039-10-02 Sun	62	—	unknown	20:35–23:10 (good, 2.58 h)	71.1° 20:40	9.22	100%	77.0°
2039-10-03 Mon	73	—	unknown	20:35–00:00 (good, 3.42 h)	71.1° 20:35	9.27	97%	85.7°
2039-10-04 Tue	83	—	unknown	20:35–00:45 (good, 4.17 h)	71.1° 20:30	9.32	93%	94.2°
2039-10-05 Wed	100	—	unknown	20:30–01:10 (good, 4.67 h)	71.1° 20:25	9.36	87%	102.6°
2039-10-06 Thu	100	—	unknown	20:30–01:15 (good, 4.75 h)	71.1° 20:25	9.41	80%	110.4°
2039-10-07 Fri	100	—	unknown	20:30–01:15 (good, 4.75 h)	71.1° 20:20	9.46	72%	117.7°
2039-10-08 Sat	100	—	unknown	20:25–01:15 (good, 4.83 h)	71.1° 20:15	9.5	64%	124.1°
2039-10-09 Sun	100	—	unknown	20:25–01:10 (good, 4.75 h)	71.1° 20:10	9.55	54%	129.2°
2039-10-10 Mon	100	—	unknown	20:25–01:10 (good, 4.75 h)	71.1° 20:05	9.59	45%	132.6°
2039-10-11 Tue	100	—	unknown	20:20–01:10 (good, 4.83 h)	71.1° 20:05	9.64	35%	133.8°
2039-10-12 Wed	100	—	unknown	20:20–01:05 (good, 4.75 h)	71.1° 20:00	9.68	26%	132.5°
2039-10-13 Thu	100	—	unknown	20:20–01:00 (good, 4.67 h)	71.1° 19:55	9.73	18%	128.7°
2039-10-14 Fri	100	—	unknown	20:15–00:55 (good, 4.67 h)	71.1° 19:50	9.77	10%	122.8°
2039-10-15 Sat	100	—	unknown	20:15–00:55 (good, 4.67 h)	71.1° 19:45	9.81	5%	115.2°
2039-10-16 Sun	100	—	unknown	20:15–00:50 (good, 4.58 h)	71.1° 19:45	9.86	1%	106.4°
2039-10-17 Mon	100	—	unknown	20:10–00:45 (good, 4.58 h)	71.1° 19:40	9.9	0%	96.8°
2039-10-18 Tue	100	—	unknown	20:10–00:40 (good, 4.5 h)	71.1° 19:35	9.94	2%	86.7°
2039-10-19 Wed	100	—	unknown	20:10–00:40 (good, 4.5 h)	71.1° 19:30	9.99	6%	76.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-09-20&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.