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: 12-22 (73), 12-21 (72), 12-23 (72), 12-24 (70), 12-25 (69) — by astronomy; check the weather when the night is within four days.

2040-12-18astronomy score per night — click a bar for that night2041-01-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-12-18 Tue	52	—	unknown	18:35–21:05 (good, 2.5 h)	87.3° 15:30	11.51	100%	99.3°
2040-12-19 Wed	57	—	unknown	18:35–21:20 (good, 2.75 h)	87.3° 15:25	11.51	98%	104.4°
2040-12-20 Thu	62	—	unknown	18:35–21:20 (good, 2.75 h)	87.2° 15:20	11.51	94%	109.0°
2040-12-21 Fri	72	—	unknown	18:35–21:25 (good, 2.83 h)	87.3° 15:20	11.51	89%	112.7°
2040-12-22 Sat	73	—	unknown	18:35–21:25 (good, 2.83 h)	87.3° 15:15	11.51	83%	115.5°
2040-12-23 Sun	72	—	unknown	18:40–21:30 (good, 2.83 h)	87.3° 15:10	11.5	75%	117.2°
2040-12-24 Mon	70	—	unknown	18:40–21:25 (good, 2.75 h)	87.3° 15:05	11.5	67%	117.6°
2040-12-25 Tue	69	—	unknown	18:40–21:25 (good, 2.75 h)	87.2° 15:05	11.5	58%	116.8°
2040-12-26 Wed	67	—	unknown	18:40–21:20 (good, 2.67 h)	87.3° 15:00	11.49	48%	114.6°
2040-12-27 Thu	65	—	unknown	18:40–21:15 (good, 2.58 h)	87.3° 14:55	11.49	38%	111.2°
2040-12-28 Fri	63	—	unknown	18:40–21:10 (good, 2.5 h)	87.3° 14:50	11.48	28%	106.7°
2040-12-29 Sat	60	—	unknown	18:40–21:05 (good, 2.42 h)	87.2° 14:45	11.47	19%	101.3°
2040-12-30 Sun	59	—	unknown	18:40–21:05 (good, 2.42 h)	87.3° 14:45	11.47	11%	95.1°
2040-12-31 Mon	56	—	unknown	18:45–21:00 (good, 2.25 h)	87.3° 14:40	11.46	5%	88.5°
2041-01-01 Tue	54	—	unknown	18:45–20:55 (good, 2.17 h)	87.3° 14:35	11.45	1%	81.8°
2041-01-02 Wed	53	—	unknown	18:45–20:50 (good, 2.08 h)	87.3° 14:30	11.44	0%	75.4°
2041-01-03 Thu	51	—	unknown	18:45–20:45 (good, 2.0 h)	87.2° 14:25	11.42	2%	69.8°
2041-01-04 Fri	48	—	unknown	18:45–20:45 (good, 2.0 h)	87.3° 14:25	11.41	7%	65.5°
2041-01-05 Sat	43	—	unknown	18:45–20:40 (good, 1.92 h)	87.3° 14:20	11.4	14%	62.9°
2041-01-06 Sun	37	—	unknown	18:50–20:25 (good, 1.58 h)	87.3° 14:15	11.38	24%	62.3°
2041-01-07 Mon	31	—	unknown	18:50–20:15 (good, 1.42 h)	87.3° 14:10	11.37	34%	63.6°
2041-01-08 Tue	27	—	unknown	18:50–20:05 (good, 1.25 h)	87.2° 14:10	11.35	45%	66.5°
2041-01-09 Wed	22	—	unknown	18:50–19:50 (good, 1.0 h)	87.3° 14:05	11.34	56%	70.5°
2041-01-10 Thu	19	—	unknown	18:50–19:00 (good, 0.17 h)	87.3° 14:00	11.32	66%	75.5°
2041-01-11 Fri	17	—	unknown	18:55–20:45 (marginal, 1.83 h)	87.3° 13:55	11.3	75%	80.9°
2041-01-12 Sat	16	—	unknown	18:55–20:40 (marginal, 1.75 h)	87.2° 13:50	11.28	83%	86.6°
2041-01-13 Sun	17	—	unknown	18:20–20:35 (marginal, 2.25 h)	87.3° 13:50	11.26	90%	92.3°
2041-01-14 Mon	18	—	unknown	18:55–19:20 (good, 0.42 h)	87.3° 13:45	11.24	95%	97.9°
2041-01-15 Tue	18	—	unknown	18:55–19:30 (good, 0.58 h)	87.3° 13:40	11.22	98%	103.2°
2041-01-16 Wed	19	—	unknown	18:55–19:35 (good, 0.67 h)	87.3° 13:35	11.2	100%	107.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-12-18&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.