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: 08-25 (100), 08-26 (100), 08-27 (100), 09-08 (100), 09-09 (100) — by astronomy; check the weather when the night is within four days.

2028-08-25astronomy score per night — click a bar for that night2028-09-23

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-08-25 Fri	100	—	unknown	21:50–04:10 (good, 6.33 h)	71.1° 23:05	7.25	38%	85.6°
2028-08-26 Sat	100	—	unknown	21:45–04:05 (good, 6.33 h)	71.1° 23:00	7.3	49%	75.4°
2028-08-27 Sun	100	—	unknown	21:45–04:05 (good, 6.33 h)	71.1° 22:55	7.36	59%	65.9°
2028-08-28 Mon	98	—	unknown	21:40–04:00 (good, 6.33 h)	71.1° 22:55	7.42	69%	57.2°
2028-08-29 Tue	91	—	unknown	21:40–03:55 (good, 6.25 h)	71.1° 22:50	7.47	78%	49.9°
2028-08-30 Wed	82	—	unknown	03:05–03:50 (good, 0.75 h)	71.1° 22:45	7.53	86%	44.3°
2028-08-31 Thu	46	—	unknown	21:35–04:15 (marginal, 6.67 h)	71.1° 22:40	7.58	92%	41.1°
2028-09-01 Fri	39	—	unknown	21:35–03:55 (marginal, 6.33 h)	71.1° 22:35	7.64	96%	40.8°
2028-09-02 Sat	37	—	unknown	21:30–03:40 (marginal, 6.17 h)	71.1° 22:35	7.7	99%	43.2°
2028-09-03 Sun	40	—	unknown	21:30–03:30 (marginal, 6.0 h)	71.1° 22:30	7.75	100%	48.0°
2028-09-04 Mon	46	—	unknown	21:30–03:25 (marginal, 5.92 h)	71.1° 22:25	7.81	99%	54.5°
2028-09-05 Tue	57	—	unknown	21:25–22:35 (good, 1.17 h)	71.1° 22:20	7.86	96%	62.1°
2028-09-06 Wed	70	—	unknown	21:25–00:20 (good, 2.92 h)	71.1° 22:15	7.92	92%	70.5°
2028-09-07 Thu	79	—	unknown	21:20–01:25 (good, 4.08 h)	71.1° 22:15	7.97	86%	79.3°
2028-09-08 Fri	100	—	unknown	21:20–02:25 (good, 5.08 h)	71.1° 22:10	8.03	79%	88.4°
2028-09-09 Sat	100	—	unknown	21:20–02:50 (good, 5.5 h)	71.1° 22:05	8.08	71%	97.7°
2028-09-10 Sun	100	—	unknown	21:15–02:55 (good, 5.67 h)	71.1° 22:00	8.13	61%	107.0°
2028-09-11 Mon	100	—	unknown	21:15–02:55 (good, 5.67 h)	71.1° 22:00	8.19	51%	116.1°
2028-09-12 Tue	100	—	unknown	21:15–02:55 (good, 5.67 h)	71.1° 21:55	8.24	41%	124.7°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-08-25&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.