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: 04-05 (100), 04-06 (100), 04-07 (100), 04-08 (100), 04-09 (100) — by astronomy; check the weather when the night is within four days.

2040-04-01astronomy score per night — click a bar for that night2040-04-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-04-01 Sun	55	—	unknown	01:50–05:30 (good, 3.67 h)	87.1° 07:15	8.05	79%	68.1°
2040-04-02 Mon	67	—	unknown	01:15–05:25 (good, 4.17 h)	87.1° 07:10	7.99	68%	65.7°
2040-04-03 Tue	85	—	unknown	01:15–05:25 (good, 4.17 h)	87.1° 07:05	7.94	57%	64.8°
2040-04-04 Wed	95	—	unknown	01:10–05:20 (good, 4.17 h)	87.1° 07:05	7.88	46%	65.5°
2040-04-05 Thu	100	—	unknown	01:05–05:20 (good, 4.25 h)	87.1° 07:00	7.83	35%	67.8°
2040-04-06 Fri	100	—	unknown	01:00–05:20 (good, 4.33 h)	87.1° 06:55	7.77	24%	71.4°
2040-04-07 Sat	100	—	unknown	00:55–05:15 (good, 4.33 h)	87.1° 06:50	7.72	16%	76.0°
2040-04-08 Sun	100	—	unknown	00:55–05:15 (good, 4.33 h)	87.1° 06:45	7.66	8%	81.3°
2040-04-09 Mon	100	—	unknown	00:50–05:15 (good, 4.42 h)	87.1° 06:45	7.6	3%	87.0°
2040-04-10 Tue	100	—	unknown	00:45–05:10 (good, 4.42 h)	87.1° 06:40	7.55	1%	92.7°
2040-04-11 Wed	100	—	unknown	00:40–05:10 (good, 4.5 h)	87.1° 06:35	7.49	0%	98.2°
2040-04-12 Thu	100	—	unknown	00:35–05:05 (good, 4.5 h)	87.1° 06:30	7.43	2%	103.2°
2040-04-13 Fri	100	—	unknown	00:35–05:05 (good, 4.5 h)	87.1° 06:30	7.37	6%	107.6°
2040-04-14 Sat	100	—	unknown	00:30–05:05 (good, 4.58 h)	87.1° 06:25	7.32	11%	111.0°
2040-04-15 Sun	100	—	unknown	00:25–05:00 (good, 4.58 h)	87.1° 06:20	7.26	18%	113.5°
2040-04-16 Mon	100	—	unknown	00:25–05:00 (good, 4.58 h)	87.1° 06:15	7.2	26%	114.9°
2040-04-17 Tue	100	—	unknown	00:20–04:55 (good, 4.58 h)	87.1° 06:10	7.14	35%	115.1°
2040-04-18 Wed	100	—	unknown	00:20–04:55 (good, 4.58 h)	87.1° 06:10	7.08	44%	114.2°
2040-04-19 Thu	100	—	unknown	00:20–04:55 (good, 4.58 h)	87.1° 06:05	7.03	54%	112.1°
2040-04-20 Fri	100	—	unknown	00:20–04:50 (good, 4.5 h)	87.1° 06:00	6.97	63%	109.1°
2040-04-21 Sat	100	—	unknown	00:20–04:50 (good, 4.5 h)	87.1° 05:55	6.91	72%	105.3°
2040-04-22 Sun	87	—	unknown	00:20–04:45 (good, 4.42 h)	87.1° 05:50	6.85	81%	100.7°
2040-04-23 Mon	83	—	unknown	00:30–04:45 (good, 4.25 h)	87.1° 05:50	6.79	88%	95.5°
2040-04-24 Tue	74	—	unknown	01:10–04:45 (good, 3.58 h)	87.1° 05:45	6.74	94%	89.9°
2040-04-25 Wed	66	—	unknown	01:45–04:40 (good, 2.92 h)	87.1° 05:40	6.68	98%	84.2°
2040-04-26 Thu	60	—	unknown	02:10–04:40 (good, 2.5 h)	87.1° 05:35	6.62	100%	78.6°
2040-04-27 Fri	57	—	unknown	02:15–04:40 (good, 2.42 h)	87.1° 05:35	6.56	99%	73.5°
2040-04-28 Sat	56	—	unknown	01:55–04:35 (good, 2.67 h)	87.1° 05:30	6.5	96%	69.3°
2040-04-29 Sun	63	—	unknown	00:25–04:35 (good, 4.17 h)	87.1° 05:25	6.44	90%	66.4°
2040-04-30 Mon	85	—	unknown	23:25–04:30 (good, 5.08 h)	87.1° 05:20	6.39	81%	65.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-04-01&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.