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: 08-27 (100), 08-28 (100), 08-29 (100), 08-30 (100), 08-31 (100) — by astronomy; check the weather when the night is within four days.

2043-08-27astronomy score per night — click a bar for that night2043-09-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-08-27 Thu	100	—	unknown	21:45–04:00 (good, 6.25 h)	71.1° 23:00	7.32	46%	108.8°
2043-08-28 Fri	100	—	unknown	21:45–04:00 (good, 6.25 h)	71.1° 22:55	7.38	34%	117.5°
2043-08-29 Sat	100	—	unknown	21:40–03:55 (good, 6.25 h)	71.1° 22:50	7.44	24%	125.0°
2043-08-30 Sun	100	—	unknown	21:40–03:55 (good, 6.25 h)	71.1° 22:50	7.49	15%	130.5°
2043-08-31 Mon	100	—	unknown	21:40–03:50 (good, 6.17 h)	71.1° 22:45	7.55	8%	133.5°
2043-09-01 Tue	100	—	unknown	21:35–03:45 (good, 6.17 h)	71.1° 22:40	7.6	3%	133.4°
2043-09-02 Wed	100	—	unknown	21:35–03:45 (good, 6.17 h)	71.1° 22:35	7.66	0%	130.4°
2043-09-03 Thu	100	—	unknown	21:30–03:40 (good, 6.17 h)	71.1° 22:30	7.72	0%	125.2°
2043-09-04 Fri	100	—	unknown	21:30–03:35 (good, 6.08 h)	71.1° 22:30	7.77	2%	118.4°
2043-09-05 Sat	100	—	unknown	21:30–03:30 (good, 6.0 h)	71.1° 22:25	7.83	6%	110.7°
2043-09-06 Sun	100	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:20	7.88	11%	102.6°
2043-09-07 Mon	100	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:15	7.94	18%	94.3°
2043-09-08 Tue	100	—	unknown	21:20–03:20 (good, 6.0 h)	71.1° 22:15	7.99	26%	86.1°
2043-09-09 Wed	100	—	unknown	21:20–03:15 (good, 5.92 h)	71.1° 22:10	8.05	35%	78.0°
2043-09-10 Thu	100	—	unknown	21:20–03:10 (good, 5.83 h)	71.1° 22:05	8.1	44%	70.1°
2043-09-11 Fri	100	—	unknown	21:15–03:05 (good, 5.83 h)	71.1° 22:00	8.15	54%	62.8°
2043-09-12 Sat	97	—	unknown	21:15–03:05 (good, 5.83 h)	71.1° 21:55	8.21	63%	56.3°
2043-09-13 Sun	89	—	unknown	21:10–03:00 (good, 5.83 h)	71.1° 21:55	8.26	72%	50.9°
2043-09-14 Mon	80	—	unknown	21:10–01:40 (good, 4.5 h)	71.1° 21:50	8.31	81%	47.4°
2043-09-15 Tue	51	—	unknown	21:10–03:15 (marginal, 6.08 h)	71.1° 21:45	8.37	88%	46.2°
2043-09-16 Wed	45	—	unknown	21:05–03:00 (marginal, 5.92 h)	71.1° 21:40	8.42	94%	47.8°
2043-09-17 Thu	43	—	unknown	21:05–02:50 (marginal, 5.75 h)	71.1° 21:35	8.47	98%	52.3°
2043-09-18 Fri	47	—	unknown	21:00–21:15 (good, 0.25 h)	71.1° 21:35	8.52	100%	58.9°
2043-09-19 Sat	56	—	unknown	21:00–22:35 (good, 1.58 h)	71.1° 21:30	8.57	99%	67.3°
2043-09-20 Sun	69	—	unknown	21:00–00:00 (good, 3.0 h)	71.1° 21:25	8.63	95%	76.7°
2043-09-21 Mon	81	—	unknown	20:55–01:05 (good, 4.17 h)	71.1° 21:20	8.68	89%	86.7°
2043-09-22 Tue	100	—	unknown	20:55–02:00 (good, 5.08 h)	71.1° 21:20	8.73	81%	96.7°
2043-09-23 Wed	100	—	unknown	20:55–02:05 (good, 5.17 h)	71.1° 21:15	8.78	71%	106.5°
2043-09-24 Thu	100	—	unknown	20:50–02:10 (good, 5.33 h)	71.1° 21:10	8.83	60%	115.5°
2043-09-25 Fri	100	—	unknown	20:50–02:05 (good, 5.25 h)	71.1° 21:05	8.88	48%	123.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-08-27&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.