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: 07-18 (100), 07-19 (100), 07-20 (100), 07-27 (100), 07-28 (100) — by astronomy; check the weather when the night is within four days.

2040-07-18astronomy score per night — click a bar for that night2040-08-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2040-08-08 Wed	100	—	unknown	22:20–04:40 (good, 6.33 h)	71.1° 00:10	6.28	1%	130.0°
2040-08-09 Thu	100	—	unknown	22:20–04:40 (good, 6.33 h)	71.1° 00:10	6.33	4%	125.4°
2040-08-10 Fri	100	—	unknown	22:15–04:40 (good, 6.42 h)	71.1° 00:05	6.39	8%	119.2°
2040-08-11 Sat	100	—	unknown	22:15–04:40 (good, 6.42 h)	71.1° 00:00	6.45	14%	112.0°
2040-08-12 Sun	100	—	unknown	22:15–04:45 (good, 6.5 h)	71.1° 23:55	6.5	22%	103.9°
2040-08-13 Mon	100	—	unknown	22:10–04:45 (good, 6.58 h)	71.1° 23:50	6.56	31%	95.3°
2040-08-14 Tue	100	—	unknown	22:10–04:45 (good, 6.58 h)	71.1° 23:50	6.62	41%	86.3°
2040-08-15 Wed	100	—	unknown	22:10–04:50 (good, 6.67 h)	71.1° 23:45	6.68	52%	77.3°
2040-08-16 Thu	100	—	unknown	22:05–04:45 (good, 6.67 h)	71.1° 23:40	6.73	63%	68.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-07-18&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.