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: 08-15 (100), 08-16 (100), 08-17 (100), 08-18 (100), 08-19 (100) — by astronomy; check the weather when the night is within four days.

2041-08-13astronomy score per night — click a bar for that night2041-09-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-08-13 Tue	69	—	unknown	22:10–00:15 (good, 2.08 h)	71.1° 23:55	6.55	95%	58.2°
2041-08-14 Wed	76	—	unknown	22:10–02:05 (good, 3.92 h)	71.1° 23:50	6.61	88%	66.5°
2041-08-15 Thu	100	—	unknown	22:10–03:10 (good, 5.0 h)	71.1° 23:45	6.66	79%	75.7°
2041-08-16 Fri	100	—	unknown	22:05–04:15 (good, 6.17 h)	71.1° 23:40	6.72	69%	85.2°
2041-08-17 Sat	100	—	unknown	22:05–04:25 (good, 6.33 h)	71.1° 23:35	6.78	59%	94.6°
2041-08-18 Sun	100	—	unknown	22:00–04:30 (good, 6.5 h)	71.1° 23:35	6.84	48%	103.5°
2041-08-19 Mon	100	—	unknown	22:00–04:30 (good, 6.5 h)	71.1° 23:30	6.89	38%	111.7°
2041-08-20 Tue	100	—	unknown	22:00–04:30 (good, 6.5 h)	71.1° 23:25	6.95	28%	119.1°
2041-08-21 Wed	100	—	unknown	21:55–04:25 (good, 6.5 h)	71.1° 23:20	7.01	20%	125.2°
2041-08-22 Thu	100	—	unknown	21:55–04:25 (good, 6.5 h)	71.1° 23:20	7.07	12%	129.8°
2041-08-23 Fri	100	—	unknown	21:55–04:20 (good, 6.42 h)	71.1° 23:15	7.12	7%	132.3°
2041-08-24 Sat	100	—	unknown	21:50–04:15 (good, 6.42 h)	71.1° 23:10	7.18	3%	132.6°
2041-08-25 Sun	100	—	unknown	21:50–04:10 (good, 6.33 h)	71.1° 23:05	7.24	1%	130.7°
2041-08-26 Mon	100	—	unknown	21:45–04:10 (good, 6.42 h)	71.1° 23:00	7.29	0%	126.9°
2041-08-27 Tue	100	—	unknown	21:45–04:05 (good, 6.33 h)	71.1° 23:00	7.35	2%	121.5°
2041-08-28 Wed	100	—	unknown	21:45–04:00 (good, 6.25 h)	71.1° 22:55	7.41	5%	115.0°
2041-08-29 Thu	100	—	unknown	21:40–03:55 (good, 6.25 h)	71.1° 22:50	7.46	9%	107.7°
2041-08-30 Fri	100	—	unknown	21:40–03:50 (good, 6.17 h)	71.1° 22:45	7.52	16%	99.8°
2041-08-31 Sat	100	—	unknown	21:35–03:50 (good, 6.25 h)	71.1° 22:40	7.58	23%	91.6°
2041-09-01 Sun	100	—	unknown	21:35–03:45 (good, 6.17 h)	71.1° 22:40	7.63	32%	83.2°
2041-09-02 Mon	100	—	unknown	21:35–03:40 (good, 6.08 h)	71.1° 22:35	7.69	42%	74.9°
2041-09-03 Tue	100	—	unknown	21:30–03:35 (good, 6.08 h)	71.1° 22:30	7.74	52%	66.7°
2041-09-04 Wed	100	—	unknown	21:30–03:35 (good, 6.08 h)	71.1° 22:25	7.8	63%	59.2°
2041-09-05 Thu	93	—	unknown	21:25–03:30 (good, 6.08 h)	71.1° 22:20	7.85	73%	52.9°
2041-09-06 Fri	83	—	unknown	21:25–03:25 (good, 6.0 h)	71.1° 22:20	7.91	83%	48.6°
2041-09-07 Sat	53	—	unknown	21:25–03:45 (marginal, 6.33 h)	71.1° 22:15	7.96	91%	47.3°
2041-09-08 Sun	49	—	unknown	21:20–03:30 (marginal, 6.17 h)	71.1° 22:10	8.02	96%	49.5°
2041-09-09 Mon	50	—	unknown	21:20–21:25 (good, 0.08 h)	71.1° 22:05	8.07	100%	54.9°
2041-09-10 Tue	57	—	unknown	21:15–22:35 (good, 1.33 h)	71.1° 22:05	8.13	100%	62.6°
2041-09-11 Wed	69	—	unknown	21:15–00:10 (good, 2.92 h)	71.1° 22:00	8.18	96%	71.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-08-13&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.