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: 06-02 (100), 06-03 (100), 06-04 (100), 06-05 (100), 06-06 (100) — by astronomy; check the weather when the night is within four days.

2040-05-16astronomy score per night — click a bar for that night2040-06-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-05-16 Wed	98	—	unknown	00:30–04:05 (good, 3.58 h)	87.3° 06:40	5.49	28%	110.7°
2040-05-17 Thu	99	—	unknown	00:25–04:05 (good, 3.67 h)	87.3° 06:35	5.44	37%	113.9°
2040-05-18 Fri	98	—	unknown	00:25–04:00 (good, 3.58 h)	87.3° 06:30	5.39	46%	116.2°
2040-05-19 Sat	97	—	unknown	00:20–04:00 (good, 3.67 h)	87.2° 06:30	5.34	56%	117.3°
2040-05-20 Sun	97	—	unknown	00:20–04:00 (good, 3.67 h)	87.3° 06:25	5.29	66%	117.0°
2040-05-21 Mon	95	—	unknown	00:20–03:55 (good, 3.58 h)	87.3° 06:20	5.24	75%	115.2°
2040-05-22 Tue	85	—	unknown	00:20–03:55 (good, 3.58 h)	87.3° 06:15	5.19	84%	112.1°
2040-05-23 Wed	79	—	unknown	00:20–03:55 (good, 3.58 h)	87.3° 06:10	5.15	91%	107.7°
2040-05-24 Thu	73	—	unknown	00:20–03:55 (good, 3.58 h)	87.3° 06:10	5.1	97%	102.2°
2040-05-25 Fri	66	—	unknown	00:20–03:50 (good, 3.5 h)	87.3° 06:05	5.05	100%	95.9°
2040-05-26 Sat	61	—	unknown	00:30–03:50 (good, 3.33 h)	87.3° 06:00	5.01	100%	89.1°
2040-05-27 Sun	59	—	unknown	00:25–03:50 (good, 3.42 h)	87.3° 05:55	4.97	97%	82.4°
2040-05-28 Mon	60	—	unknown	00:10–03:50 (good, 3.67 h)	87.2° 05:50	4.93	91%	76.0°
2040-05-29 Tue	75	—	unknown	23:35–03:50 (good, 4.25 h)	87.3° 05:50	4.89	84%	70.5°
2040-05-30 Wed	86	—	unknown	23:30–03:45 (good, 4.25 h)	87.3° 05:45	4.85	74%	66.3°
2040-05-31 Thu	92	—	unknown	23:25–03:45 (good, 4.33 h)	87.3° 05:40	4.81	63%	63.6°
2040-06-01 Fri	96	—	unknown	23:20–03:45 (good, 4.42 h)	87.3° 05:35	4.77	52%	62.7°
2040-06-02 Sat	100	—	unknown	23:20–03:45 (good, 4.42 h)	87.2° 05:35	4.74	41%	63.4°
2040-06-03 Sun	100	—	unknown	23:15–03:45 (good, 4.5 h)	87.3° 05:30	4.71	31%	65.7°
2040-06-04 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 05:25	4.67	21%	69.2°
2040-06-05 Tue	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:20	4.64	14%	73.6°
2040-06-06 Wed	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:15	4.62	8%	78.7°
2040-06-07 Thu	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:15	4.59	3%	84.1°
2040-06-08 Fri	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:10	4.57	1%	89.7°
2040-06-09 Sat	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.3° 05:05	4.54	0%	95.2°
2040-06-10 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 05:00	4.52	1%	100.5°
2040-06-11 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:55	4.5	4%	105.3°
2040-06-12 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:55	4.49	9%	109.6°
2040-06-13 Wed	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:50	4.47	15%	113.1°
2040-06-14 Thu	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:45	4.46	22%	115.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-05-16&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.