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 V1057 Cyg: 08-18 (100), 08-19 (100), 08-20 (100), 08-21 (100), 08-22 (100) — by astronomy; check the weather when the night is within four days.

2041-08-18astronomy score per night — click a bar for that night2041-09-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-08-18 Sun	100	—	unknown	22:00–04:55 (good, 6.92 h)	87.3° 00:30	6.84	48%	82.8°
2041-08-19 Mon	100	—	unknown	22:00–04:55 (good, 6.92 h)	87.2° 00:25	6.89	38%	88.9°
2041-08-20 Tue	100	—	unknown	22:00–04:55 (good, 6.92 h)	87.2° 00:25	6.95	28%	94.9°
2041-08-21 Wed	100	—	unknown	21:55–04:55 (good, 7.0 h)	87.3° 00:20	7.01	20%	100.6°
2041-08-22 Thu	100	—	unknown	21:55–05:00 (good, 7.08 h)	87.3° 00:15	7.07	12%	105.8°
2041-08-23 Fri	100	—	unknown	21:55–05:00 (good, 7.08 h)	87.3° 00:10	7.12	7%	110.3°
2041-08-24 Sat	100	—	unknown	21:50–05:00 (good, 7.17 h)	87.2° 00:05	7.18	3%	114.0°
2041-08-25 Sun	100	—	unknown	21:50–05:05 (good, 7.25 h)	87.3° 00:05	7.24	1%	116.6°
2041-08-26 Mon	100	—	unknown	21:45–05:05 (good, 7.33 h)	87.3° 00:00	7.29	0%	118.1°
2041-08-27 Tue	100	—	unknown	21:45–05:05 (good, 7.33 h)	87.3° 23:55	7.35	2%	118.3°
2041-08-28 Wed	100	—	unknown	21:45–05:05 (good, 7.33 h)	87.3° 23:50	7.41	5%	117.2°
2041-08-29 Thu	100	—	unknown	21:40–05:10 (good, 7.5 h)	87.2° 23:50	7.46	9%	114.8°
2041-08-30 Fri	100	—	unknown	21:40–05:10 (good, 7.5 h)	87.3° 23:45	7.52	16%	111.3°
2041-08-31 Sat	100	—	unknown	21:35–05:10 (good, 7.58 h)	87.3° 23:40	7.58	23%	106.9°
2041-09-01 Sun	100	—	unknown	21:35–05:15 (good, 7.67 h)	87.3° 23:35	7.63	32%	101.8°
2041-09-02 Mon	100	—	unknown	21:35–05:15 (good, 7.67 h)	87.2° 23:30	7.69	42%	96.1°
2041-09-03 Tue	100	—	unknown	21:30–05:15 (good, 7.75 h)	87.2° 23:30	7.74	52%	89.9°
2041-09-04 Wed	100	—	unknown	21:30–05:15 (good, 7.75 h)	87.3° 23:25	7.8	63%	83.6°
2041-09-05 Thu	100	—	unknown	21:25–05:20 (good, 7.92 h)	87.3° 23:20	7.85	73%	77.4°
2041-09-06 Fri	97	—	unknown	21:25–05:20 (good, 7.92 h)	87.3° 23:15	7.91	83%	71.6°
2041-09-07 Sat	87	—	unknown	21:25–05:20 (good, 7.92 h)	87.2° 23:10	7.96	91%	66.7°
2041-09-08 Sun	69	—	unknown	21:20–23:10 (good, 1.83 h)	87.3° 23:10	8.02	96%	63.3°
2041-09-09 Mon	63	—	unknown	21:20–22:15 (good, 0.92 h)	87.3° 23:05	8.07	100%	61.7°
2041-09-10 Tue	66	—	unknown	21:15–22:30 (good, 1.25 h)	87.3° 23:00	8.13	100%	62.3°
2041-09-11 Wed	70	—	unknown	21:15–23:25 (good, 2.17 h)	87.3° 22:55	8.18	96%	64.9°
2041-09-12 Thu	75	—	unknown	21:15–01:10 (good, 3.92 h)	87.2° 22:55	8.23	91%	69.2°
2041-09-13 Fri	100	—	unknown	21:10–02:30 (good, 5.33 h)	87.3° 22:50	8.29	83%	74.6°
2041-09-14 Sat	100	—	unknown	21:10–03:35 (good, 6.42 h)	87.3° 22:45	8.34	74%	80.7°
2041-09-15 Sun	100	—	unknown	21:05–04:30 (good, 7.42 h)	87.3° 22:40	8.39	63%	86.9°
2041-09-16 Mon	100	—	unknown	21:05–04:35 (good, 7.5 h)	87.2° 22:35	8.44	53%	93.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-08-18&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.