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: 07-12 (2), 07-07 (1), 07-08 (1), 07-09 (1), 07-10 (1) — by astronomy; check the weather when the night is within four days.

2027-06-13astronomy score per night — click a bar for that night2027-07-12

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-06-13 Sun	0	—	unknown	—	72.5° 11:40	4.48	76%	143.9°
2027-06-14 Mon	0	—	unknown	—	72.5° 11:35	4.47	84%	156.8°
2027-06-15 Tue	0	—	unknown	—	72.5° 11:30	4.45	91%	169.5°
2027-06-16 Wed	0	—	unknown	—	72.5° 11:30	4.44	96%	177.8°
2027-06-17 Thu	0	—	unknown	—	72.5° 11:25	4.44	99%	165.6°
2027-06-18 Fri	0	—	unknown	—	72.5° 11:20	4.43	100%	153.4°
2027-06-19 Sat	0	—	unknown	—	72.5° 11:15	4.42	99%	141.4°
2027-06-20 Sun	0	—	unknown	—	72.5° 11:10	4.42	97%	129.5°
2027-06-21 Mon	0	—	unknown	—	72.5° 11:10	4.42	92%	117.6°
2027-06-22 Tue	0	—	unknown	—	72.5° 11:05	4.42	87%	105.8°
2027-06-23 Wed	0	—	unknown	—	72.5° 11:00	4.43	80%	93.9°
2027-06-24 Thu	0	—	unknown	—	72.5° 10:55	4.43	72%	82.0°
2027-06-25 Fri	0	—	unknown	—	72.5° 10:50	4.44	62%	69.9°
2027-06-26 Sat	0	—	unknown	—	72.5° 10:50	4.45	53%	57.6°
2027-06-27 Sun	0	—	unknown	—	72.5° 10:45	4.46	43%	45.0°
2027-06-28 Mon	0	—	unknown	—	72.5° 10:40	4.48	32%	32.1°
2027-06-29 Tue	0	—	unknown	—	72.5° 10:35	4.49	23%	18.7°
2027-06-30 Wed	0	—	unknown	—	72.5° 10:35	4.51	14%	4.9°
2027-07-01 Thu	0	—	unknown	—	72.5° 10:30	4.53	7%	9.5°
2027-07-02 Fri	0	—	unknown	—	72.5° 10:25	4.55	2%	24.2°
2027-07-03 Sat	0	—	unknown	—	72.5° 10:20	4.58	0%	39.2°
2027-07-04 Sun	0	—	unknown	—	72.5° 10:15	4.6	1%	54.4°
2027-07-05 Mon	0	—	unknown	—	72.5° 10:15	4.63	5%	69.5°
2027-07-06 Tue	0	—	unknown	—	72.5° 10:10	4.66	11%	84.5°
2027-07-07 Wed	1	—	unknown	—	72.5° 10:05	4.69	20%	99.2°
2027-07-08 Thu	1	—	unknown	—	72.5° 10:00	4.72	30%	113.4°
2027-07-09 Fri	1	—	unknown	—	72.5° 09:55	4.76	41%	127.3°
2027-07-10 Sat	1	—	unknown	—	72.5° 09:55	4.79	52%	140.8°
2027-07-11 Sun	1	—	unknown	—	72.5° 09:50	4.83	62%	153.8°
2027-07-12 Mon	2	—	unknown	04:40–04:45 (marginal, 0.08 h)	72.5° 09:45	4.87	72%	166.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-06-13&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.