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 North America Nebula: 05-20 (100), 05-21 (100), 05-22 (100), 05-23 (100), 05-24 (100) — by astronomy; check the weather when the night is within four days.

2028-05-19astronomy score per night — click a bar for that night2028-06-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-05-19 Fri	98	—	unknown	00:15–04:00 (good, 3.75 h)	87.2° 06:30	5.34	19%	57.1°
2028-05-20 Sat	100	—	unknown	00:10–04:00 (good, 3.83 h)	87.2° 06:25	5.29	12%	61.2°
2028-05-21 Sun	100	—	unknown	00:05–03:55 (good, 3.83 h)	87.3° 06:20	5.24	6%	66.6°
2028-05-22 Mon	100	—	unknown	00:00–03:55 (good, 3.92 h)	87.2° 06:15	5.2	2%	73.1°
2028-05-23 Tue	100	—	unknown	23:55–03:55 (good, 4.0 h)	87.2° 06:10	5.15	0%	80.4°
2028-05-24 Wed	100	—	unknown	23:55–03:55 (good, 4.0 h)	87.2° 06:10	5.1	0%	88.2°
2028-05-25 Thu	100	—	unknown	23:50–03:50 (good, 4.0 h)	87.2° 06:05	5.06	3%	96.2°
2028-05-26 Fri	100	—	unknown	23:45–03:50 (good, 4.08 h)	87.3° 06:00	5.01	8%	104.1°
2028-05-27 Sat	100	—	unknown	23:45–03:50 (good, 4.08 h)	87.2° 05:55	4.97	15%	111.5°
2028-05-28 Sun	100	—	unknown	23:40–03:50 (good, 4.17 h)	87.2° 05:50	4.93	24%	117.9°
2028-05-29 Mon	100	—	unknown	23:35–03:50 (good, 4.25 h)	87.2° 05:50	4.89	34%	122.9°
2028-05-30 Tue	100	—	unknown	23:35–03:45 (good, 4.17 h)	87.2° 05:45	4.85	46%	125.8°
2028-05-31 Wed	100	—	unknown	23:30–03:45 (good, 4.25 h)	87.3° 05:40	4.81	57%	126.2°
2028-06-01 Thu	100	—	unknown	23:30–03:45 (good, 4.25 h)	87.2° 05:35	4.78	68%	124.1°
2028-06-02 Fri	100	—	unknown	23:30–03:45 (good, 4.25 h)	87.2° 05:35	4.74	78%	119.8°
2028-06-03 Sat	100	—	unknown	23:30–03:45 (good, 4.25 h)	87.2° 05:30	4.71	87%	113.8°
2028-06-04 Sun	88	—	unknown	23:30–03:40 (good, 4.17 h)	87.3° 05:25	4.68	93%	106.7°
2028-06-05 Mon	80	—	unknown	23:30–03:40 (good, 4.17 h)	87.2° 05:20	4.65	98%	99.0°
2028-06-06 Tue	71	—	unknown	23:35–03:40 (good, 4.08 h)	87.2° 05:15	4.62	100%	91.1°
2028-06-07 Wed	64	—	unknown	23:45–03:40 (good, 3.92 h)	87.2° 05:15	4.59	99%	83.3°
2028-06-08 Thu	59	—	unknown	23:55–03:40 (good, 3.75 h)	87.2° 05:10	4.57	97%	75.9°
2028-06-09 Fri	61	—	unknown	23:30–03:40 (good, 4.17 h)	87.3° 05:05	4.54	92%	69.1°
2028-06-10 Sat	74	—	unknown	23:05–03:40 (good, 4.58 h)	87.2° 05:00	4.52	86%	63.3°
2028-06-11 Sun	80	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:55	4.5	79%	58.6°
2028-06-12 Mon	88	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:55	4.49	71%	55.3°
2028-06-13 Tue	91	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:50	4.47	62%	53.7°
2028-06-14 Wed	94	—	unknown	23:10–03:40 (good, 4.5 h)	87.3° 04:45	4.46	52%	53.9°
2028-06-15 Thu	97	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:40	4.45	43%	55.9°
2028-06-16 Fri	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:35	4.44	34%	59.5°
2028-06-17 Sat	100	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 04:35	4.43	25%	64.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-05-19&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.