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 Seven Sisters: 07-16 (4), 07-17 (4), 07-15 (3), 07-12 (2), 07-13 (2) — by astronomy; check the weather when the night is within four days.

2043-06-18astronomy score per night — click a bar for that night2043-07-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-06-18 Thu	0	—	unknown	—	72.6° 11:20	4.43	88%	167.4°
2043-06-19 Fri	0	—	unknown	—	72.6° 11:15	4.42	93%	179.2°
2043-06-20 Sat	0	—	unknown	—	72.5° 11:10	4.42	97%	168.9°
2043-06-21 Sun	0	—	unknown	—	72.5° 11:10	4.42	99%	156.8°
2043-06-22 Mon	0	—	unknown	—	72.6° 11:05	4.42	100%	144.7°
2043-06-23 Tue	0	—	unknown	—	72.6° 11:00	4.43	98%	132.4°
2043-06-24 Wed	0	—	unknown	—	72.5° 10:55	4.43	94%	119.9°
2043-06-25 Thu	0	—	unknown	—	72.5° 10:55	4.44	89%	107.2°
2043-06-26 Fri	0	—	unknown	—	72.6° 10:50	4.45	82%	94.3°
2043-06-27 Sat	0	—	unknown	—	72.6° 10:45	4.47	73%	81.2°
2043-06-28 Sun	0	—	unknown	—	72.6° 10:40	4.48	63%	67.8°
2043-06-29 Mon	0	—	unknown	—	72.5° 10:35	4.5	52%	54.2°
2043-06-30 Tue	0	—	unknown	—	72.5° 10:35	4.51	41%	40.2°
2043-07-01 Wed	0	—	unknown	—	72.6° 10:30	4.53	30%	26.0°
2043-07-02 Thu	0	—	unknown	—	72.6° 10:25	4.56	20%	11.5°
2043-07-03 Fri	0	—	unknown	—	72.6° 10:20	4.58	11%	3.2°
2043-07-04 Sat	0	—	unknown	—	72.5° 10:15	4.61	5%	18.0°
2043-07-05 Sun	0	—	unknown	—	72.5° 10:15	4.63	1%	32.8°
2043-07-06 Mon	0	—	unknown	—	72.6° 10:10	4.66	0%	47.5°
2043-07-07 Tue	1	—	unknown	—	72.6° 10:05	4.69	2%	61.8°
2043-07-08 Wed	1	—	unknown	—	72.6° 10:00	4.73	6%	75.9°
2043-07-09 Thu	1	—	unknown	—	72.5° 10:00	4.76	13%	89.5°
2043-07-10 Fri	1	—	unknown	—	72.6° 09:55	4.8	21%	102.7°
2043-07-11 Sat	1	—	unknown	—	72.6° 09:50	4.83	30%	115.5°
2043-07-12 Sun	2	—	unknown	04:40–04:45 (marginal, 0.08 h)	72.6° 09:45	4.87	39%	127.9°
2043-07-13 Mon	2	—	unknown	04:35–04:45 (marginal, 0.17 h)	72.5° 09:40	4.91	49%	140.1°
2043-07-14 Tue	2	—	unknown	04:30–04:45 (marginal, 0.25 h)	72.5° 09:40	4.95	58%	152.1°
2043-07-15 Wed	3	—	unknown	04:30–04:50 (marginal, 0.33 h)	72.6° 09:35	4.99	67%	163.9°
2043-07-16 Thu	4	—	unknown	04:25–04:50 (marginal, 0.42 h)	72.6° 09:30	5.04	76%	175.8°
2043-07-17 Fri	4	—	unknown	04:20–04:50 (marginal, 0.5 h)	72.6° 09:25	5.08	84%	172.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-06-18&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.