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: 07-09 (100), 07-10 (100), 07-11 (100), 07-12 (100), 07-13 (100) — by astronomy; check the weather when the night is within four days.

2040-07-09astronomy score per night — click a bar for that night2040-08-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-07-09 Mon	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:10	4.79	0%	132.0°
2040-07-10 Tue	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:05	4.82	2%	133.2°
2040-07-11 Wed	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:00	4.86	6%	132.1°
2040-07-12 Thu	100	—	unknown	23:05–03:55 (good, 4.83 h)	71.1° 02:00	4.9	11%	128.9°
2040-07-13 Fri	100	—	unknown	23:00–04:00 (good, 5.0 h)	71.1° 01:55	4.94	18%	123.9°
2040-07-14 Sat	100	—	unknown	23:00–04:00 (good, 5.0 h)	71.1° 01:50	4.98	26%	117.5°
2040-07-15 Sun	100	—	unknown	23:00–04:00 (good, 5.0 h)	71.1° 01:45	5.02	35%	109.9°
2040-07-16 Mon	100	—	unknown	23:00–04:00 (good, 5.0 h)	71.1° 01:40	5.07	45%	101.7°
2040-07-17 Tue	100	—	unknown	22:55–04:05 (good, 5.17 h)	71.1° 01:40	5.11	56%	92.8°
2040-07-18 Wed	100	—	unknown	22:55–04:05 (good, 5.17 h)	71.1° 01:35	5.16	66%	83.6°
2040-07-19 Thu	100	—	unknown	22:55–04:05 (good, 5.17 h)	71.1° 01:30	5.21	77%	74.2°
2040-07-20 Fri	100	—	unknown	22:55–04:10 (good, 5.25 h)	71.1° 01:25	5.25	86%	65.2°
2040-07-21 Sat	98	—	unknown	23:15–04:10 (good, 4.92 h)	71.1° 01:20	5.3	93%	57.1°
2040-07-22 Sun	57	—	unknown	02:40–04:10 (good, 1.5 h)	71.1° 01:20	5.35	98%	50.7°
2040-07-23 Mon	48	—	unknown	22:50–04:10 (marginal, 5.33 h)	71.1° 01:15	5.4	100%	47.2°
2040-07-24 Tue	51	—	unknown	22:45–04:15 (marginal, 5.5 h)	71.1° 01:10	5.45	99%	47.3°
2040-07-25 Wed	60	—	unknown	22:45–00:15 (good, 1.5 h)	71.1° 01:05	5.5	95%	51.0°
2040-07-26 Thu	98	—	unknown	22:45–02:10 (good, 3.42 h)	71.1° 01:05	5.56	88%	57.3°
2040-07-27 Fri	100	—	unknown	22:40–03:45 (good, 5.08 h)	71.1° 01:00	5.61	80%	65.1°
2040-07-28 Sat	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 00:55	5.66	70%	73.8°
2040-07-29 Sun	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 00:50	5.72	60%	82.7°
2040-07-30 Mon	100	—	unknown	22:35–04:25 (good, 5.83 h)	71.1° 00:45	5.77	49%	91.5°
2040-07-31 Tue	100	—	unknown	22:35–04:25 (good, 5.83 h)	71.1° 00:45	5.83	39%	100.0°
2040-08-01 Wed	100	—	unknown	22:35–04:25 (good, 5.83 h)	71.1° 00:40	5.88	30%	108.1°
2040-08-02 Thu	100	—	unknown	22:30–04:30 (good, 6.0 h)	71.1° 00:35	5.94	22%	115.6°
2040-08-03 Fri	100	—	unknown	22:30–04:30 (good, 6.0 h)	71.1° 00:30	5.99	14%	122.1°
2040-08-04 Sat	100	—	unknown	22:30–04:30 (good, 6.0 h)	71.1° 00:25	6.05	8%	127.5°
2040-08-05 Sun	100	—	unknown	22:25–04:35 (good, 6.17 h)	71.1° 00:25	6.1	4%	131.3°
2040-08-06 Mon	100	—	unknown	22:25–04:35 (good, 6.17 h)	71.1° 00:20	6.16	1%	133.1°
2040-08-07 Tue	100	—	unknown	22:25–04:35 (good, 6.17 h)	71.1° 00:15	6.22	0%	132.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-07-09&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.