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 Vega: 04-16 (100), 04-17 (100), 04-18 (100), 04-19 (100), 04-20 (100) — by astronomy; check the weather when the night is within four days.

2031-04-09astronomy score per night — click a bar for that night2031-05-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-04-09 Wed	54	—	unknown	02:45–05:15 (good, 2.5 h)	87.1° 06:45	7.65	94%	75.7°
2031-04-10 Thu	53	—	unknown	02:20–05:10 (good, 2.83 h)	87.1° 06:40	7.59	87%	69.1°
2031-04-11 Fri	58	—	unknown	01:15–05:10 (good, 3.92 h)	87.1° 06:40	7.53	78%	63.7°
2031-04-12 Sat	76	—	unknown	00:40–05:10 (good, 4.5 h)	87.1° 06:35	7.48	68%	59.8°
2031-04-13 Sun	88	—	unknown	00:35–05:05 (good, 4.5 h)	87.1° 06:30	7.42	57%	57.9°
2031-04-14 Mon	93	—	unknown	00:30–05:05 (good, 4.58 h)	87.1° 06:25	7.36	46%	58.2°
2031-04-15 Tue	99	—	unknown	00:30–05:00 (good, 4.5 h)	87.1° 06:25	7.31	34%	60.6°
2031-04-16 Wed	100	—	unknown	00:25–05:00 (good, 4.58 h)	87.1° 06:20	7.25	24%	64.7°
2031-04-17 Thu	100	—	unknown	00:20–05:00 (good, 4.67 h)	87.1° 06:15	7.19	16%	70.1°
2031-04-18 Fri	100	—	unknown	00:15–04:55 (good, 4.67 h)	87.1° 06:10	7.13	8%	76.4°
2031-04-19 Sat	100	—	unknown	00:15–04:55 (good, 4.67 h)	87.1° 06:05	7.07	4%	83.2°
2031-04-20 Sun	100	—	unknown	00:10–04:55 (good, 4.75 h)	87.1° 06:05	7.02	1%	90.1°
2031-04-21 Mon	100	—	unknown	00:05–04:50 (good, 4.75 h)	87.1° 06:00	6.96	0%	96.9°
2031-04-22 Tue	100	—	unknown	00:00–04:50 (good, 4.83 h)	87.1° 05:55	6.9	2%	103.4°
2031-04-23 Wed	100	—	unknown	23:55–04:45 (good, 4.83 h)	87.1° 05:50	6.84	5%	109.2°
2031-04-24 Thu	100	—	unknown	23:55–04:45 (good, 4.83 h)	87.1° 05:45	6.78	10%	114.2°
2031-04-25 Fri	100	—	unknown	23:50–04:45 (good, 4.92 h)	87.1° 05:45	6.72	16%	118.2°
2031-04-26 Sat	100	—	unknown	23:45–04:40 (good, 4.92 h)	87.1° 05:40	6.67	24%	120.9°
2031-04-27 Sun	100	—	unknown	23:45–04:40 (good, 4.92 h)	87.1° 05:35	6.61	32%	122.2°
2031-04-28 Mon	100	—	unknown	23:40–04:35 (good, 4.92 h)	87.1° 05:30	6.55	42%	122.0°
2031-04-29 Tue	100	—	unknown	23:40–04:35 (good, 4.92 h)	87.1° 05:30	6.49	51%	120.2°
2031-04-30 Wed	100	—	unknown	23:40–04:35 (good, 4.92 h)	87.1° 05:25	6.43	61%	117.0°
2031-05-01 Thu	100	—	unknown	23:40–04:30 (good, 4.83 h)	87.1° 05:20	6.38	70%	112.5°
2031-05-02 Fri	100	—	unknown	23:40–04:30 (good, 4.83 h)	87.1° 05:15	6.32	79%	106.9°
2031-05-03 Sat	100	—	unknown	23:45–04:30 (good, 4.75 h)	87.1° 05:10	6.26	87%	100.5°
2031-05-04 Sun	82	—	unknown	23:55–04:25 (good, 4.5 h)	87.1° 05:10	6.2	94%	93.4°
2031-05-05 Mon	76	—	unknown	00:40–04:25 (good, 3.75 h)	87.1° 05:05	6.14	98%	85.9°
2031-05-06 Tue	67	—	unknown	01:15–04:25 (good, 3.17 h)	87.1° 05:00	6.09	100%	78.4°
2031-05-07 Wed	60	—	unknown	01:40–04:20 (good, 2.67 h)	87.1° 04:55	6.03	99%	71.4°
2031-05-08 Thu	57	—	unknown	01:35–04:20 (good, 2.75 h)	87.1° 04:50	5.97	96%	65.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-04-09&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.