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: 01-24 (100), 01-25 (100), 01-26 (100), 01-27 (100), 01-28 (100) — by astronomy; check the weather when the night is within four days.

2027-01-19astronomy score per night — click a bar for that night2027-02-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-01-19 Tue	18	—	unknown	19:00–20:40 (marginal, 1.67 h)	72.5° 20:15	11.14	90%	23.4°
2027-01-20 Wed	22	—	unknown	19:00–22:20 (marginal, 3.33 h)	72.5° 20:10	11.11	96%	38.5°
2027-01-21 Thu	38	—	unknown	19:00–00:55 (marginal, 5.92 h)	72.5° 20:05	11.09	100%	53.7°
2027-01-22 Fri	60	—	unknown	19:05–20:40 (good, 1.58 h)	72.5° 20:00	11.06	100%	68.9°
2027-01-23 Sat	79	—	unknown	19:05–23:10 (good, 4.08 h)	72.5° 20:00	11.04	97%	84.0°
2027-01-24 Sun	100	—	unknown	19:05–00:40 (good, 5.58 h)	72.5° 19:55	11.01	92%	98.7°
2027-01-25 Mon	100	—	unknown	19:05–00:50 (good, 5.75 h)	72.5° 19:50	10.98	84%	113.0°
2027-01-26 Tue	100	—	unknown	19:05–00:50 (good, 5.75 h)	72.5° 19:45	10.95	75%	126.9°
2027-01-27 Wed	100	—	unknown	19:10–00:45 (good, 5.58 h)	72.5° 19:40	10.92	65%	140.2°
2027-01-28 Thu	100	—	unknown	19:10–00:50 (good, 5.67 h)	72.5° 19:40	10.89	55%	153.1°
2027-01-29 Fri	100	—	unknown	19:10–00:45 (good, 5.58 h)	72.5° 19:35	10.86	45%	165.6°
2027-01-30 Sat	100	—	unknown	19:10–00:40 (good, 5.5 h)	72.5° 19:30	10.83	36%	177.6°
2027-01-31 Sun	100	—	unknown	19:15–00:35 (good, 5.33 h)	72.5° 19:25	10.8	27%	170.0°
2027-02-01 Mon	100	—	unknown	19:15–00:35 (good, 5.33 h)	72.5° 19:20	10.77	19%	158.2°
2027-02-02 Tue	100	—	unknown	19:15–00:30 (good, 5.25 h)	72.5° 19:20	10.73	12%	146.4°
2027-02-03 Wed	100	—	unknown	19:15–00:25 (good, 5.17 h)	72.5° 19:15	10.7	7%	134.6°
2027-02-04 Thu	100	—	unknown	19:15–00:20 (good, 5.08 h)	72.5° 19:10	10.66	3%	122.7°
2027-02-05 Fri	100	—	unknown	19:20–00:15 (good, 4.92 h)	72.5° 19:05	10.63	0%	110.8°
2027-02-06 Sat	100	—	unknown	19:20–00:15 (good, 4.92 h)	72.5° 19:05	10.59	0%	98.8°
2027-02-07 Sun	100	—	unknown	19:20–00:10 (good, 4.83 h)	72.5° 19:00	10.56	2%	86.6°
2027-02-08 Mon	100	—	unknown	19:20–00:05 (good, 4.75 h)	72.5° 18:55	10.52	5%	74.3°
2027-02-09 Tue	100	—	unknown	19:25–00:00 (good, 4.58 h)	72.5° 18:50	10.49	10%	61.9°
2027-02-10 Wed	93	—	unknown	19:25–00:00 (good, 4.58 h)	72.5° 18:45	10.45	17%	49.2°
2027-02-11 Thu	87	—	unknown	19:25–23:55 (good, 4.5 h)	72.5° 18:45	10.41	25%	36.3°
2027-02-12 Fri	71	—	unknown	19:25–23:35 (good, 4.17 h)	72.5° 18:40	10.37	35%	23.2°
2027-02-13 Sat	54	—	unknown	19:25–23:20 (good, 3.92 h)	72.5° 18:35	10.33	46%	9.8°
2027-02-14 Sun	38	—	unknown	19:30–00:05 (marginal, 4.58 h)	72.5° 18:30	10.3	57%	4.2°
2027-02-15 Mon	25	—	unknown	19:30–23:45 (marginal, 4.25 h)	72.5° 18:25	10.26	68%	18.1°
2027-02-16 Tue	18	—	unknown	19:30–23:25 (marginal, 3.92 h)	72.5° 18:25	10.22	78%	32.5°
2027-02-17 Wed	20	—	unknown	19:30–23:20 (marginal, 3.83 h)	72.5° 18:20	10.18	87%	47.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-01-19&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.