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: 05-18 (100), 05-19 (100), 05-20 (100), 05-21 (100), 05-22 (100) — by astronomy; check the weather when the night is within four days.

2042-05-18astronomy score per night — click a bar for that night2042-06-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-05-18 Sun	100	—	unknown	00:20–04:00 (good, 3.67 h)	87.3° 06:35	5.41	0%	78.3°
2042-05-19 Mon	100	—	unknown	00:15–04:00 (good, 3.75 h)	87.3° 06:30	5.36	0%	85.1°
2042-05-20 Tue	100	—	unknown	00:10–04:00 (good, 3.83 h)	87.3° 06:25	5.31	3%	92.0°
2042-05-21 Wed	100	—	unknown	00:05–04:00 (good, 3.92 h)	87.2° 06:20	5.26	8%	98.6°
2042-05-22 Thu	100	—	unknown	00:05–03:55 (good, 3.83 h)	87.2° 06:20	5.22	15%	104.7°
2042-05-23 Fri	100	—	unknown	00:00–03:55 (good, 3.92 h)	87.3° 06:15	5.17	23%	109.9°
2042-05-24 Sat	100	—	unknown	00:00–03:55 (good, 3.92 h)	87.3° 06:10	5.12	32%	114.1°
2042-05-25 Sun	100	—	unknown	23:55–03:55 (good, 4.0 h)	87.3° 06:05	5.08	42%	117.0°
2042-05-26 Mon	100	—	unknown	23:55–03:50 (good, 3.92 h)	87.2° 06:00	5.03	52%	118.7°
2042-05-27 Tue	100	—	unknown	23:50–03:50 (good, 4.0 h)	87.3° 06:00	4.99	61%	118.9°
2042-05-28 Wed	100	—	unknown	23:50–03:50 (good, 4.0 h)	87.3° 05:55	4.95	70%	117.8°
2042-05-29 Thu	100	—	unknown	23:50–03:50 (good, 4.0 h)	87.3° 05:50	4.91	78%	115.5°
2042-05-30 Fri	91	—	unknown	23:50–03:45 (good, 3.92 h)	87.3° 05:45	4.87	86%	112.0°
2042-05-31 Sat	87	—	unknown	23:50–03:45 (good, 3.92 h)	87.2° 05:45	4.83	92%	107.6°
2042-06-01 Sun	81	—	unknown	23:50–03:45 (good, 3.92 h)	87.3° 05:40	4.79	96%	102.5°
2042-06-02 Mon	75	—	unknown	23:50–03:45 (good, 3.92 h)	87.3° 05:35	4.76	99%	96.7°
2042-06-03 Tue	70	—	unknown	23:45–03:45 (good, 4.0 h)	87.3° 05:30	4.72	100%	90.7°
2042-06-04 Wed	65	—	unknown	23:45–03:45 (good, 4.0 h)	87.2° 05:25	4.69	99%	84.4°
2042-06-05 Thu	63	—	unknown	23:40–03:40 (good, 4.0 h)	87.2° 05:25	4.66	95%	78.3°
2042-06-06 Fri	75	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:20	4.63	90%	72.6°
2042-06-07 Sat	84	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:15	4.6	82%	67.7°
2042-06-08 Sun	91	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:10	4.58	73%	63.9°
2042-06-09 Mon	94	—	unknown	23:05–03:40 (good, 4.58 h)	87.2° 05:05	4.55	62%	61.5°
2042-06-10 Tue	97	—	unknown	23:05–03:40 (good, 4.58 h)	87.2° 05:05	4.53	51%	61.0°
2042-06-11 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 05:00	4.51	40%	62.3°
2042-06-12 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:55	4.49	29%	65.5°
2042-06-13 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:50	4.48	19%	70.2°
2042-06-14 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:50	4.46	11%	76.0°
2042-06-15 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:45	4.45	5%	82.5°
2042-06-16 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:40	4.44	1%	89.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-05-18&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.