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: 07-25 (100), 07-26 (100), 07-27 (100), 07-28 (100), 07-29 (100) — by astronomy; check the weather when the night is within four days.

2027-07-21astronomy score per night — click a bar for that night2027-08-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-07-21 Wed	54	—	unknown	22:50–23:55 (good, 1.08 h)	71.1° 01:25	5.26	91%	46.3°
2027-07-22 Thu	66	—	unknown	22:50–01:20 (good, 2.5 h)	71.1° 01:20	5.31	84%	51.6°
2027-07-23 Fri	97	—	unknown	22:50–03:25 (good, 4.58 h)	71.1° 01:15	5.36	77%	58.5°
2027-07-24 Sat	99	—	unknown	22:50–04:15 (good, 5.42 h)	71.1° 01:15	5.41	68%	66.6°
2027-07-25 Sun	100	—	unknown	22:45–04:15 (good, 5.5 h)	71.1° 01:10	5.46	58%	75.4°
2027-07-26 Mon	100	—	unknown	22:45–04:15 (good, 5.5 h)	71.1° 01:05	5.51	48%	84.8°
2027-07-27 Tue	100	—	unknown	22:45–04:15 (good, 5.5 h)	71.1° 01:00	5.56	37%	94.6°
2027-07-28 Wed	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 01:00	5.62	27%	104.7°
2027-07-29 Thu	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 00:55	5.67	17%	114.6°
2027-07-30 Fri	100	—	unknown	22:40–04:20 (good, 5.67 h)	71.1° 00:50	5.72	9%	123.9°
2027-07-31 Sat	100	—	unknown	22:35–04:25 (good, 5.83 h)	71.1° 00:45	5.78	3%	131.6°
2027-08-01 Sun	100	—	unknown	22:35–04:25 (good, 5.83 h)	71.1° 00:40	5.83	0%	136.6°
2027-08-02 Mon	100	—	unknown	22:35–04:25 (good, 5.83 h)	71.1° 00:40	5.89	0%	137.6°
2027-08-03 Tue	100	—	unknown	22:30–04:30 (good, 6.0 h)	71.1° 00:35	5.94	4%	134.3°
2027-08-04 Wed	100	—	unknown	22:30–04:30 (good, 6.0 h)	71.1° 00:30	6.0	9%	127.8°
2027-08-05 Thu	100	—	unknown	22:30–04:30 (good, 6.0 h)	71.1° 00:25	6.06	17%	119.3°
2027-08-06 Fri	100	—	unknown	22:25–04:35 (good, 6.17 h)	71.1° 00:20	6.11	26%	109.9°
2027-08-07 Sat	100	—	unknown	22:25–04:35 (good, 6.17 h)	71.1° 00:20	6.17	37%	100.1°
2027-08-08 Sun	100	—	unknown	22:25–04:35 (good, 6.17 h)	71.1° 00:15	6.23	47%	90.5°
2027-08-09 Mon	100	—	unknown	22:20–04:40 (good, 6.33 h)	71.1° 00:10	6.28	57%	81.1°
2027-08-10 Tue	100	—	unknown	22:20–04:40 (good, 6.33 h)	71.1° 00:05	6.34	67%	72.1°
2027-08-11 Wed	100	—	unknown	22:15–04:40 (good, 6.42 h)	71.1° 00:05	6.4	76%	63.7°
2027-08-12 Thu	97	—	unknown	22:15–04:40 (good, 6.42 h)	71.1° 00:00	6.46	84%	56.2°
2027-08-13 Fri	89	—	unknown	00:05–04:45 (good, 4.67 h)	71.1° 23:55	6.51	90%	49.8°
2027-08-14 Sat	81	—	unknown	04:20–04:45 (good, 0.42 h)	71.1° 23:50	6.57	95%	45.1°
2027-08-15 Sun	46	—	unknown	22:10–04:45 (marginal, 6.58 h)	71.1° 23:45	6.63	98%	42.5°
2027-08-16 Mon	44	—	unknown	22:05–04:50 (marginal, 6.75 h)	71.1° 23:45	6.69	100%	42.6°
2027-08-17 Tue	45	—	unknown	22:05–04:45 (marginal, 6.67 h)	71.1° 23:40	6.74	100%	45.3°
2027-08-18 Wed	51	—	unknown	21:25–04:40 (marginal, 7.25 h)	71.1° 23:35	6.8	98%	50.2°
2027-08-19 Thu	62	—	unknown	22:00–23:15 (good, 1.25 h)	71.1° 23:30	6.86	94%	56.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-07-21&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.