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: 04-28 (100), 04-29 (100), 04-30 (100), 05-01 (100), 05-02 (100) — by astronomy; check the weather when the night is within four days.

2027-04-22astronomy score per night — click a bar for that night2027-05-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-04-22 Thu	62	—	unknown	01:25–04:50 (good, 3.42 h)	87.1° 05:55	6.9	96%	76.4°
2027-04-23 Fri	63	—	unknown	00:40–04:45 (good, 4.08 h)	87.1° 05:50	6.84	90%	71.9°
2027-04-24 Sat	79	—	unknown	23:55–04:45 (good, 4.83 h)	87.1° 05:45	6.78	84%	68.4°
2027-04-25 Sun	87	—	unknown	23:50–04:45 (good, 4.92 h)	87.1° 05:45	6.73	76%	65.8°
2027-04-26 Mon	92	—	unknown	23:45–04:40 (good, 4.92 h)	87.1° 05:40	6.67	68%	64.4°
2027-04-27 Tue	97	—	unknown	23:40–04:40 (good, 5.0 h)	87.1° 05:35	6.61	59%	64.1°
2027-04-28 Wed	100	—	unknown	23:35–04:35 (good, 5.0 h)	87.1° 05:30	6.55	49%	65.0°
2027-04-29 Thu	100	—	unknown	23:35–04:35 (good, 5.0 h)	87.1° 05:30	6.49	40%	67.1°
2027-04-30 Fri	100	—	unknown	23:30–04:35 (good, 5.08 h)	87.1° 05:25	6.43	31%	70.2°
2027-05-01 Sat	100	—	unknown	23:25–04:30 (good, 5.08 h)	87.1° 05:20	6.38	22%	74.2°
2027-05-02 Sun	100	—	unknown	23:20–04:30 (good, 5.17 h)	87.1° 05:15	6.32	14%	79.0°
2027-05-03 Mon	100	—	unknown	23:20–04:30 (good, 5.17 h)	87.1° 05:10	6.26	8%	84.4°
2027-05-04 Tue	100	—	unknown	23:15–04:25 (good, 5.17 h)	87.1° 05:10	6.2	3%	90.2°
2027-05-05 Wed	100	—	unknown	23:10–04:25 (good, 5.25 h)	87.1° 05:05	6.15	0%	96.2°
2027-05-06 Thu	100	—	unknown	23:05–04:25 (good, 5.33 h)	87.1° 05:00	6.09	0%	102.0°
2027-05-07 Fri	100	—	unknown	23:00–04:20 (good, 5.33 h)	87.1° 04:55	6.03	3%	107.3°
2027-05-08 Sat	100	—	unknown	23:00–04:20 (good, 5.33 h)	87.1° 04:50	5.98	8%	111.6°
2027-05-09 Sun	100	—	unknown	22:55–04:15 (good, 5.33 h)	87.1° 04:50	5.92	16%	114.6°
2027-05-10 Mon	100	—	unknown	22:55–04:15 (good, 5.33 h)	87.1° 04:45	5.86	25%	116.0°
2027-05-11 Tue	100	—	unknown	22:50–04:15 (good, 5.42 h)	87.1° 04:40	5.81	36%	115.6°
2027-05-12 Wed	100	—	unknown	22:50–04:10 (good, 5.33 h)	87.1° 04:35	5.75	47%	113.6°
2027-05-13 Thu	100	—	unknown	22:50–04:10 (good, 5.33 h)	87.1° 04:35	5.7	58%	110.2°
2027-05-14 Fri	100	—	unknown	22:50–04:10 (good, 5.33 h)	87.1° 04:30	5.64	69%	105.7°
2027-05-15 Sat	100	—	unknown	22:55–04:05 (good, 5.17 h)	87.1° 04:25	5.59	79%	100.4°
2027-05-16 Sun	100	—	unknown	22:55–04:05 (good, 5.17 h)	87.1° 04:20	5.54	87%	94.7°
2027-05-17 Mon	81	—	unknown	23:15–04:05 (good, 4.83 h)	87.1° 04:15	5.48	93%	88.9°
2027-05-18 Tue	77	—	unknown	23:40–04:05 (good, 4.42 h)	87.1° 04:15	5.43	97%	83.2°
2027-05-19 Wed	73	—	unknown	23:55–04:00 (good, 4.08 h)	87.1° 04:10	5.38	100%	77.9°
2027-05-20 Thu	68	—	unknown	23:55–04:00 (good, 4.08 h)	87.1° 04:05	5.33	100%	73.2°
2027-05-21 Fri	66	—	unknown	23:15–04:00 (good, 4.75 h)	87.1° 04:00	5.28	98%	69.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-04-22&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.