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: 09-13 (100), 09-14 (100), 09-15 (100), 09-16 (100), 09-17 (100) — by astronomy; check the weather when the night is within four days.

2028-09-13astronomy score per night — click a bar for that night2028-10-12

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-09-13 Wed	100	—	unknown	21:10–02:55 (good, 5.75 h)	71.1° 21:50	8.29	30%	132.2°
2028-09-14 Thu	100	—	unknown	21:10–02:50 (good, 5.67 h)	71.1° 21:45	8.35	20%	137.6°
2028-09-15 Fri	100	—	unknown	21:05–02:50 (good, 5.75 h)	71.1° 21:40	8.4	12%	139.5°
2028-09-16 Sat	100	—	unknown	21:05–02:45 (good, 5.67 h)	71.1° 21:40	8.45	5%	137.1°
2028-09-17 Sun	100	—	unknown	21:05–02:40 (good, 5.58 h)	71.1° 21:35	8.5	1%	130.9°
2028-09-18 Mon	100	—	unknown	21:00–02:35 (good, 5.58 h)	71.1° 21:30	8.56	0%	121.9°
2028-09-19 Tue	100	—	unknown	21:00–02:35 (good, 5.58 h)	71.1° 21:25	8.61	2%	111.5°
2028-09-20 Wed	100	—	unknown	20:55–02:30 (good, 5.58 h)	71.1° 21:20	8.66	7%	100.5°
2028-09-21 Thu	100	—	unknown	20:55–02:25 (good, 5.5 h)	71.1° 21:20	8.71	14%	89.4°
2028-09-22 Fri	100	—	unknown	20:55–02:20 (good, 5.42 h)	71.1° 21:15	8.76	23%	78.6°
2028-09-23 Sat	100	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:10	8.81	33%	68.5°
2028-09-24 Sun	100	—	unknown	20:50–02:15 (good, 5.42 h)	71.1° 21:05	8.86	44%	59.4°
2028-09-25 Mon	94	—	unknown	20:50–02:10 (good, 5.33 h)	71.1° 21:05	8.91	54%	51.5°
2028-09-26 Tue	85	—	unknown	20:45–02:05 (good, 5.33 h)	71.1° 21:00	8.96	64%	45.3°
2028-09-27 Wed	57	—	unknown	20:45–00:20 (good, 3.58 h)	71.1° 20:55	9.01	73%	41.5°
2028-09-28 Thu	44	—	unknown	20:40–02:20 (marginal, 5.67 h)	71.1° 20:50	9.06	81%	40.4°
2028-09-29 Fri	37	—	unknown	20:40–02:05 (marginal, 5.42 h)	71.1° 20:45	9.11	88%	42.2°
2028-09-30 Sat	34	—	unknown	20:40–01:50 (marginal, 5.17 h)	71.1° 20:45	9.16	93%	46.5°
2028-10-01 Sun	35	—	unknown	20:35–01:45 (marginal, 5.17 h)	71.1° 20:40	9.2	97%	52.7°
2028-10-02 Mon	39	—	unknown	20:35–01:40 (marginal, 5.08 h)	71.1° 20:35	9.25	99%	60.1°
2028-10-03 Tue	47	—	unknown	20:35–21:30 (good, 0.92 h)	71.1° 20:30	9.3	100%	68.3°
2028-10-04 Wed	58	—	unknown	20:30–22:50 (good, 2.33 h)	71.1° 20:25	9.35	98%	77.1°
2028-10-05 Thu	70	—	unknown	20:30–23:50 (good, 3.33 h)	71.1° 20:25	9.39	95%	86.3°
2028-10-06 Fri	84	—	unknown	20:30–00:45 (good, 4.25 h)	71.1° 20:20	9.44	90%	95.6°
2028-10-07 Sat	100	—	unknown	20:25–01:00 (good, 4.58 h)	71.1° 20:15	9.49	84%	104.9°
2028-10-08 Sun	100	—	unknown	20:25–01:05 (good, 4.67 h)	71.1° 20:10	9.53	76%	114.0°
2028-10-09 Mon	100	—	unknown	20:25–01:05 (good, 4.67 h)	71.1° 20:10	9.58	66%	122.7°
2028-10-10 Tue	100	—	unknown	20:20–01:05 (good, 4.75 h)	71.1° 20:05	9.62	56%	130.4°
2028-10-11 Wed	100	—	unknown	20:20–01:05 (good, 4.75 h)	71.1° 20:00	9.67	45%	136.4°
2028-10-12 Thu	100	—	unknown	20:20–01:00 (good, 4.67 h)	71.1° 19:55	9.71	34%	139.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-09-13&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.