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 V1057 Cyg: 12-18 (86), 12-19 (84), 12-20 (82), 12-21 (79), 12-22 (77) — by astronomy; check the weather when the night is within four days.

2027-12-18astronomy score per night — click a bar for that night2028-01-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-12-18 Sat	86	—	unknown	18:35–21:55 (good, 3.33 h)	87.3° 15:35	11.5	66%	125.5°
2027-12-19 Sun	84	—	unknown	18:35–21:50 (good, 3.25 h)	87.3° 15:30	11.51	55%	125.6°
2027-12-20 Mon	82	—	unknown	18:35–21:45 (good, 3.17 h)	87.3° 15:25	11.51	44%	123.3°
2027-12-21 Tue	79	—	unknown	18:35–21:40 (good, 3.08 h)	87.3° 15:20	11.51	33%	119.0°
2027-12-22 Wed	77	—	unknown	18:35–21:35 (good, 3.0 h)	87.3° 15:15	11.51	24%	113.3°
2027-12-23 Thu	74	—	unknown	18:40–21:35 (good, 2.92 h)	87.3° 15:15	11.51	15%	106.6°
2027-12-24 Fri	72	—	unknown	18:40–21:30 (good, 2.83 h)	87.3° 15:10	11.5	8%	99.4°
2027-12-25 Sat	70	—	unknown	18:40–21:25 (good, 2.75 h)	87.3° 15:05	11.5	4%	92.0°
2027-12-26 Sun	68	—	unknown	18:40–21:20 (good, 2.67 h)	87.3° 15:00	11.5	1%	84.7°
2027-12-27 Mon	66	—	unknown	18:40–21:20 (good, 2.67 h)	87.3° 15:00	11.49	0%	77.6°
2027-12-28 Tue	65	—	unknown	18:40–21:15 (good, 2.58 h)	87.3° 14:55	11.49	1%	71.0°
2027-12-29 Wed	63	—	unknown	18:40–21:10 (good, 2.5 h)	87.3° 14:50	11.48	4%	65.1°
2027-12-30 Thu	58	—	unknown	18:40–21:05 (good, 2.42 h)	87.3° 14:45	11.47	9%	60.2°
2027-12-31 Fri	51	—	unknown	18:45–21:00 (good, 2.25 h)	87.3° 14:40	11.46	15%	56.6°
2028-01-01 Sat	46	—	unknown	18:45–20:50 (good, 2.08 h)	87.3° 14:40	11.45	22%	54.5°
2028-01-02 Sun	40	—	unknown	18:45–20:40 (good, 1.92 h)	87.3° 14:35	11.44	30%	54.1°
2028-01-03 Mon	33	—	unknown	18:45–20:25 (good, 1.67 h)	87.3° 14:30	11.43	39%	55.5°
2028-01-04 Tue	28	—	unknown	18:45–20:15 (good, 1.5 h)	87.3° 14:25	11.42	49%	58.5°
2028-01-05 Wed	23	—	unknown	18:45–19:05 (good, 0.33 h)	87.3° 14:20	11.41	58%	63.1°
2028-01-06 Thu	20	—	unknown	18:45–21:05 (marginal, 2.33 h)	87.3° 14:20	11.4	68%	69.0°
2028-01-07 Fri	19	—	unknown	18:50–21:00 (marginal, 2.17 h)	87.3° 14:15	11.38	78%	75.9°
2028-01-08 Sat	19	—	unknown	18:50–20:55 (marginal, 2.08 h)	87.3° 14:10	11.37	86%	83.6°
2028-01-09 Sun	20	—	unknown	18:50–19:05 (good, 0.25 h)	87.3° 14:05	11.35	93%	91.9°
2028-01-10 Mon	23	—	unknown	18:50–19:45 (good, 0.92 h)	87.3° 14:05	11.33	98%	100.3°
2028-01-11 Tue	26	—	unknown	18:50–19:55 (good, 1.08 h)	87.3° 14:00	11.31	100%	108.4°
2028-01-12 Wed	28	—	unknown	18:55–20:00 (good, 1.08 h)	87.3° 13:55	11.3	99%	115.7°
2028-01-13 Thu	32	—	unknown	18:55–20:00 (good, 1.08 h)	87.3° 13:50	11.28	95%	121.5°
2028-01-14 Fri	32	—	unknown	18:55–20:05 (good, 1.17 h)	87.3° 13:45	11.26	89%	125.0°
2028-01-15 Sat	31	—	unknown	18:55–20:05 (good, 1.17 h)	87.3° 13:45	11.24	80%	125.9°
2028-01-16 Sun	30	—	unknown	18:55–20:00 (good, 1.08 h)	87.3° 13:40	11.21	70%	124.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-12-18&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.