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: 05-18 (100), 05-19 (100), 05-20 (100), 05-21 (100), 05-22 (100) — by astronomy; check the weather when the night is within four days.

2039-05-13astronomy score per night — click a bar for that night2039-06-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-05-13 Fri	72	—	unknown	00:40–04:10 (good, 3.5 h)	87.2° 06:55	5.69	63%	66.3°
2039-05-14 Sat	81	—	unknown	00:35–04:10 (good, 3.58 h)	87.2° 06:50	5.64	52%	63.7°
2039-05-15 Sun	88	—	unknown	00:30–04:05 (good, 3.58 h)	87.2° 06:45	5.59	42%	62.6°
2039-05-16 Mon	95	—	unknown	00:25–04:05 (good, 3.67 h)	87.2° 06:40	5.53	32%	63.0°
2039-05-17 Tue	99	—	unknown	00:25–04:05 (good, 3.67 h)	87.2° 06:40	5.48	23%	64.9°
2039-05-18 Wed	100	—	unknown	00:20–04:05 (good, 3.75 h)	87.2° 06:35	5.43	15%	67.8°
2039-05-19 Thu	100	—	unknown	00:15–04:00 (good, 3.75 h)	87.2° 06:30	5.38	9%	71.7°
2039-05-20 Fri	100	—	unknown	00:10–04:00 (good, 3.83 h)	87.2° 06:25	5.33	4%	76.3°
2039-05-21 Sat	100	—	unknown	00:10–04:00 (good, 3.83 h)	87.2° 06:25	5.28	1%	81.4°
2039-05-22 Sun	100	—	unknown	00:05–03:55 (good, 3.83 h)	87.2° 06:20	5.23	0%	86.7°
2039-05-23 Mon	100	—	unknown	00:00–03:55 (good, 3.92 h)	87.2° 06:15	5.18	1%	92.1°
2039-05-24 Tue	100	—	unknown	23:55–03:55 (good, 4.0 h)	87.2° 06:10	5.13	3%	97.5°
2039-05-25 Wed	100	—	unknown	23:50–03:55 (good, 4.08 h)	87.2° 06:05	5.09	7%	102.6°
2039-05-26 Thu	100	—	unknown	23:50–03:50 (good, 4.0 h)	87.2° 06:05	5.04	13%	107.3°
2039-05-27 Fri	100	—	unknown	23:45–03:50 (good, 4.08 h)	87.2° 06:00	5.0	20%	111.4°
2039-05-28 Sat	100	—	unknown	23:45–03:50 (good, 4.08 h)	87.2° 05:55	4.96	28%	114.6°
2039-05-29 Sun	100	—	unknown	23:40–03:50 (good, 4.17 h)	87.2° 05:50	4.92	38%	116.6°
2039-05-30 Mon	100	—	unknown	23:40–03:45 (good, 4.08 h)	87.2° 05:45	4.88	48%	117.4°
2039-05-31 Tue	100	—	unknown	23:40–03:45 (good, 4.08 h)	87.2° 05:45	4.84	59%	116.6°
2039-06-01 Wed	100	—	unknown	23:35–03:45 (good, 4.17 h)	87.2° 05:40	4.8	69%	114.2°
2039-06-02 Thu	100	—	unknown	23:40–03:45 (good, 4.08 h)	87.2° 05:35	4.77	79%	110.3°
2039-06-03 Fri	87	—	unknown	23:40–03:45 (good, 4.08 h)	87.2° 05:30	4.73	88%	105.1°
2039-06-04 Sat	79	—	unknown	23:40–03:45 (good, 4.08 h)	87.2° 05:30	4.7	95%	98.9°
2039-06-05 Sun	70	—	unknown	23:55–03:40 (good, 3.75 h)	87.2° 05:25	4.67	99%	92.0°
2039-06-06 Mon	63	—	unknown	00:15–03:40 (good, 3.42 h)	87.2° 05:20	4.64	100%	85.0°
2039-06-07 Tue	59	—	unknown	00:10–03:40 (good, 3.5 h)	87.2° 05:15	4.61	98%	78.4°
2039-06-08 Wed	60	—	unknown	23:30–03:40 (good, 4.17 h)	87.2° 05:10	4.58	93%	72.5°
2039-06-09 Thu	79	—	unknown	23:05–03:40 (good, 4.58 h)	87.2° 05:10	4.56	86%	67.7°
2039-06-10 Fri	89	—	unknown	23:05–03:40 (good, 4.58 h)	87.2° 05:05	4.54	77%	64.5°
2039-06-11 Sat	94	—	unknown	23:10–03:40 (good, 4.5 h)	87.2° 05:00	4.52	67%	62.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-05-13&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.