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: 05-26 (100), 05-27 (100), 05-28 (100), 05-29 (100), 05-30 (100) — by astronomy; check the weather when the night is within four days.

2027-05-18astronomy score per night — click a bar for that night2027-06-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2027-05-22 Sat	84	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:55	5.23	94%	66.3°
2027-05-23 Sun	90	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:55	5.19	89%	64.5°
2027-05-24 Mon	94	—	unknown	22:45–03:55 (good, 5.17 h)	87.1° 03:50	5.14	82%	63.8°
2027-05-25 Tue	98	—	unknown	22:50–03:55 (good, 5.08 h)	87.1° 03:45	5.09	74%	64.3°
2027-05-26 Wed	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:40	5.05	66%	66.0°
2027-05-27 Thu	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:40	5.0	56%	68.8°
2027-05-28 Fri	100	—	unknown	22:50–03:50 (good, 5.0 h)	87.1° 03:35	4.96	47%	72.5°
2027-05-29 Sat	100	—	unknown	22:55–03:50 (good, 4.92 h)	87.1° 03:30	4.92	37%	77.0°
2027-05-30 Sun	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:25	4.88	27%	82.1°
2027-05-31 Mon	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:20	4.84	19%	87.8°
2027-06-01 Tue	100	—	unknown	22:55–03:45 (good, 4.83 h)	87.1° 03:20	4.8	11%	93.7°
2027-06-02 Wed	100	—	unknown	23:00–03:45 (good, 4.75 h)	87.1° 03:15	4.77	5%	99.6°
2027-06-03 Thu	100	—	unknown	23:00–03:45 (good, 4.75 h)	87.1° 03:10	4.73	1%	105.3°
2027-06-04 Fri	100	—	unknown	23:00–03:45 (good, 4.75 h)	87.1° 03:05	4.7	0%	110.1°
2027-06-05 Sat	100	—	unknown	23:00–03:40 (good, 4.67 h)	87.1° 03:00	4.67	2%	113.8°
2027-06-06 Sun	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 03:00	4.64	6%	115.9°
2027-06-07 Mon	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:55	4.61	14%	116.1°
2027-06-08 Tue	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:50	4.59	23%	114.5°
2027-06-09 Wed	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:45	4.56	33%	111.4°
2027-06-10 Thu	100	—	unknown	23:05–03:40 (good, 4.58 h)	87.1° 02:45	4.54	44%	107.0°
2027-06-11 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:40	4.52	55%	101.8°
2027-06-12 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:35	4.5	66%	96.2°
2027-06-13 Sun	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:30	4.48	76%	90.4°
2027-06-14 Mon	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:25	4.47	84%	84.7°
2027-06-15 Tue	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:25	4.45	91%	79.3°
2027-06-16 Wed	76	—	unknown	23:10–03:40 (good, 4.5 h)	87.1° 02:20	4.44	96%	74.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-05-18&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.