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: 08-20 (100), 08-21 (100), 08-22 (100), 08-23 (100), 08-24 (100) — by astronomy; check the weather when the night is within four days.

2044-08-20astronomy score per night — click a bar for that night2044-09-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-08-20 Sat	100	—	unknown	22:00–04:30 (good, 6.5 h)	71.1° 23:25	6.97	6%	133.6°
2044-08-21 Sun	100	—	unknown	21:55–04:25 (good, 6.5 h)	71.1° 23:20	7.02	2%	135.1°
2044-08-22 Mon	100	—	unknown	21:55–04:25 (good, 6.5 h)	71.1° 23:15	7.08	0%	133.0°
2044-08-23 Tue	100	—	unknown	21:50–04:20 (good, 6.5 h)	71.1° 23:15	7.14	1%	127.8°
2044-08-24 Wed	100	—	unknown	21:50–04:15 (good, 6.42 h)	71.1° 23:10	7.2	5%	120.4°
2044-08-25 Thu	100	—	unknown	21:50–04:10 (good, 6.33 h)	71.1° 23:05	7.25	10%	112.0°
2044-08-26 Fri	100	—	unknown	21:45–04:05 (good, 6.33 h)	71.1° 23:00	7.31	18%	103.1°
2044-08-27 Sat	100	—	unknown	21:45–04:05 (good, 6.33 h)	71.1° 22:55	7.37	27%	94.0°
2044-08-28 Sun	100	—	unknown	21:40–04:00 (good, 6.33 h)	71.1° 22:55	7.42	36%	85.2°
2044-08-29 Mon	100	—	unknown	21:40–03:55 (good, 6.25 h)	71.1° 22:50	7.48	46%	76.6°
2044-08-30 Tue	100	—	unknown	21:40–03:50 (good, 6.17 h)	71.1° 22:45	7.54	55%	68.5°
2044-08-31 Wed	100	—	unknown	21:35–03:50 (good, 6.25 h)	71.1° 22:40	7.59	64%	61.1°
2044-09-01 Thu	95	—	unknown	21:35–03:45 (good, 6.17 h)	71.1° 22:35	7.65	73%	54.6°
2044-09-02 Fri	87	—	unknown	21:30–03:40 (good, 6.17 h)	71.1° 22:35	7.7	81%	49.4°
2044-09-03 Sat	70	—	unknown	03:20–03:35 (good, 0.25 h)	71.1° 22:30	7.76	88%	46.0°
2044-09-04 Sun	47	—	unknown	21:30–03:50 (marginal, 6.33 h)	71.1° 22:25	7.81	94%	44.8°
2044-09-05 Mon	43	—	unknown	21:25–03:35 (marginal, 6.17 h)	71.1° 22:20	7.87	98%	46.3°
2044-09-06 Tue	43	—	unknown	21:25–03:25 (marginal, 6.0 h)	71.1° 22:20	7.92	100%	50.2°
2044-09-07 Wed	48	—	unknown	21:20–21:30 (good, 0.17 h)	71.1° 22:15	7.98	100%	56.2°
2044-09-08 Thu	58	—	unknown	21:20–22:40 (good, 1.33 h)	71.1° 22:10	8.03	98%	63.6°
2044-09-09 Fri	70	—	unknown	21:20–00:20 (good, 3.0 h)	71.1° 22:05	8.09	94%	72.1°
2044-09-10 Sat	80	—	unknown	21:15–01:25 (good, 4.17 h)	71.1° 22:00	8.14	87%	81.4°
2044-09-11 Sun	100	—	unknown	21:15–02:25 (good, 5.17 h)	71.1° 22:00	8.19	79%	91.0°
2044-09-12 Mon	100	—	unknown	21:10–02:40 (good, 5.5 h)	71.1° 21:55	8.25	69%	100.6°
2044-09-13 Tue	100	—	unknown	21:10–02:45 (good, 5.58 h)	71.1° 21:50	8.3	58%	110.1°
2044-09-14 Wed	100	—	unknown	21:10–02:45 (good, 5.58 h)	71.1° 21:45	8.35	47%	119.0°
2044-09-15 Thu	100	—	unknown	21:05–02:45 (good, 5.67 h)	71.1° 21:40	8.41	36%	126.6°
2044-09-16 Fri	100	—	unknown	21:05–02:45 (good, 5.67 h)	71.1° 21:40	8.46	25%	132.3°
2044-09-17 Sat	100	—	unknown	21:05–02:40 (good, 5.58 h)	71.1° 21:35	8.51	16%	135.0°
2044-09-18 Sun	100	—	unknown	21:00–02:35 (good, 5.58 h)	71.1° 21:30	8.56	8%	134.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-08-20&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.