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: 08-17 (100), 08-18 (100), 08-19 (100), 08-20 (100), 08-21 (100) — by astronomy; check the weather when the night is within four days.

2045-08-17astronomy score per night — click a bar for that night2045-09-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-08-17 Thu	100	—	unknown	22:05–04:45 (good, 6.67 h)	71.1° 23:35	6.78	34%	95.3°
2045-08-18 Fri	100	—	unknown	22:00–04:40 (good, 6.67 h)	71.1° 23:35	6.84	44%	85.6°
2045-08-19 Sat	100	—	unknown	22:00–04:35 (good, 6.58 h)	71.1° 23:30	6.9	55%	76.3°
2045-08-20 Sun	100	—	unknown	22:00–04:30 (good, 6.5 h)	71.1° 23:25	6.95	64%	67.6°
2045-08-21 Mon	100	—	unknown	21:55–04:30 (good, 6.58 h)	71.1° 23:20	7.01	74%	59.7°
2045-08-22 Tue	93	—	unknown	21:55–04:25 (good, 6.5 h)	71.1° 23:20	7.07	82%	52.9°
2045-08-23 Wed	85	—	unknown	00:10–03:05 (good, 2.92 h)	71.1° 23:15	7.13	88%	47.6°
2045-08-24 Thu	57	—	unknown	21:50–04:45 (marginal, 6.92 h)	71.1° 23:10	7.18	94%	44.2°
2045-08-25 Fri	45	—	unknown	21:50–04:25 (marginal, 6.58 h)	71.1° 23:05	7.24	98%	43.3°
2045-08-26 Sat	43	—	unknown	21:45–04:15 (marginal, 6.5 h)	71.1° 23:00	7.3	100%	44.9°
2045-08-27 Sun	45	—	unknown	21:45–04:05 (marginal, 6.33 h)	71.1° 23:00	7.35	100%	48.8°
2045-08-28 Mon	52	—	unknown	21:45–22:00 (good, 0.25 h)	71.1° 22:55	7.41	98%	54.6°
2045-08-29 Tue	62	—	unknown	21:40–23:15 (good, 1.58 h)	71.1° 22:50	7.47	95%	61.6°
2045-08-30 Wed	74	—	unknown	21:40–00:55 (good, 3.25 h)	71.1° 22:45	7.52	90%	69.6°
2045-08-31 Thu	80	—	unknown	21:35–02:00 (good, 4.42 h)	71.1° 22:40	7.58	83%	78.3°
2045-09-01 Fri	100	—	unknown	21:35–03:00 (good, 5.42 h)	71.1° 22:40	7.63	75%	87.3°
2045-09-02 Sat	100	—	unknown	21:35–03:20 (good, 5.75 h)	71.1° 22:35	7.69	66%	96.6°
2045-09-03 Sun	100	—	unknown	21:30–03:25 (good, 5.92 h)	71.1° 22:30	7.74	55%	106.0°
2045-09-04 Mon	100	—	unknown	21:30–03:25 (good, 5.92 h)	71.1° 22:25	7.8	44%	115.1°
2045-09-05 Tue	100	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:25	7.86	34%	123.6°
2045-09-06 Wed	100	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:20	7.91	23%	130.8°
2045-09-07 Thu	100	—	unknown	21:25–03:20 (good, 5.92 h)	71.1° 22:15	7.96	14%	135.5°
2045-09-08 Fri	100	—	unknown	21:20–03:15 (good, 5.92 h)	71.1° 22:10	8.02	7%	136.7°
2045-09-09 Sat	100	—	unknown	21:20–03:15 (good, 5.92 h)	71.1° 22:05	8.07	2%	133.8°
2045-09-10 Sun	100	—	unknown	21:15–03:10 (good, 5.92 h)	71.1° 22:05	8.13	0%	127.5°
2045-09-11 Mon	100	—	unknown	21:15–03:05 (good, 5.83 h)	71.1° 22:00	8.18	1%	119.0°
2045-09-12 Tue	100	—	unknown	21:15–03:00 (good, 5.75 h)	71.1° 21:55	8.23	5%	109.3°
2045-09-13 Wed	100	—	unknown	21:10–02:55 (good, 5.75 h)	71.1° 21:50	8.29	11%	99.1°
2045-09-14 Thu	100	—	unknown	21:10–02:55 (good, 5.75 h)	71.1° 21:45	8.34	20%	89.0°
2045-09-15 Fri	100	—	unknown	21:05–02:50 (good, 5.75 h)	71.1° 21:45	8.39	29%	79.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-08-17&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.