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: 02-23 (23), 02-22 (22), 02-20 (21), 02-21 (20), 02-19 (19) — by astronomy; check the weather when the night is within four days.

2031-01-25astronomy score per night — click a bar for that night2031-02-23

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-01-25 Sat	15	—	unknown	19:05–19:20 (good, 0.25 h)	87.3° 13:05	10.98	10%	52.5°
2031-01-26 Sun	13	—	unknown	19:05–19:10 (good, 0.08 h)	87.3° 13:00	10.95	18%	54.5°
2031-01-27 Mon	10	—	unknown	19:10–19:50 (marginal, 0.67 h)	87.3° 12:55	10.92	27%	58.5°
2031-01-28 Tue	9	—	unknown	19:10–19:45 (marginal, 0.58 h)	87.3° 12:50	10.89	36%	64.0°
2031-01-29 Wed	7	—	unknown	19:10–19:40 (marginal, 0.5 h)	87.3° 12:45	10.86	46%	70.3°
2031-01-30 Thu	7	—	unknown	19:10–19:40 (marginal, 0.5 h)	87.3° 12:45	10.83	56%	77.2°
2031-01-31 Fri	7	—	unknown	05:45–06:00 (marginal, 0.25 h)	87.3° 12:40	10.8	65%	84.3°
2031-02-01 Sat	8	—	unknown	05:40–06:00 (marginal, 0.33 h)	87.3° 12:35	10.76	74%	91.6°
2031-02-02 Sun	8	—	unknown	05:40–06:00 (marginal, 0.33 h)	87.3° 12:30	10.73	82%	98.7°
2031-02-03 Mon	8	—	unknown	05:35–06:00 (marginal, 0.42 h)	87.3° 12:25	10.7	88%	105.7°
2031-02-04 Tue	8	—	unknown	05:30–05:55 (marginal, 0.42 h)	87.3° 12:25	10.66	94%	112.2°
2031-02-05 Wed	8	—	unknown	05:25–05:55 (marginal, 0.5 h)	87.3° 12:20	10.63	97%	118.0°
2031-02-06 Thu	8	—	unknown	05:20–05:55 (marginal, 0.58 h)	87.3° 12:15	10.59	100%	122.7°
2031-02-07 Fri	8	—	unknown	05:20–05:55 (marginal, 0.58 h)	87.3° 12:10	10.56	100%	126.1°
2031-02-08 Sat	9	—	unknown	05:15–05:55 (marginal, 0.67 h)	87.3° 12:10	10.52	98%	127.5°
2031-02-09 Sun	9	—	unknown	05:10–05:50 (marginal, 0.67 h)	87.3° 12:00	10.48	94%	126.9°
2031-02-10 Mon	9	—	unknown	05:05–05:50 (marginal, 0.75 h)	87.3° 12:00	10.45	88%	124.1°
2031-02-11 Tue	10	—	unknown	05:00–06:20 (marginal, 1.33 h)	87.3° 11:50	10.41	81%	119.4°
2031-02-12 Wed	10	—	unknown	05:45–05:50 (good, 0.08 h)	87.3° 11:50	10.37	72%	113.2°
2031-02-13 Thu	10	—	unknown	04:55–06:20 (marginal, 1.42 h)	87.3° 11:45	10.33	61%	105.9°
2031-02-14 Fri	11	—	unknown	05:40–05:45 (good, 0.08 h)	87.3° 11:40	10.29	50%	97.8°
2031-02-15 Sat	12	—	unknown	05:35–05:45 (good, 0.17 h)	87.3° 11:35	10.25	39%	89.3°
2031-02-16 Sun	14	—	unknown	05:25–05:45 (good, 0.33 h)	87.3° 11:30	10.21	28%	80.6°
2031-02-17 Mon	15	—	unknown	05:20–05:40 (good, 0.33 h)	87.3° 11:30	10.17	18%	72.3°
2031-02-18 Tue	17	—	unknown	05:10–05:40 (good, 0.5 h)	87.3° 11:25	10.13	10%	64.7°
2031-02-19 Wed	19	—	unknown	05:05–05:40 (good, 0.58 h)	87.3° 11:20	10.09	4%	58.4°
2031-02-20 Thu	21	—	unknown	05:00–05:40 (good, 0.67 h)	87.3° 11:15	10.05	1%	54.2°
2031-02-21 Fri	20	—	unknown	05:00–05:35 (good, 0.58 h)	87.3° 11:15	10.01	0%	52.5°
2031-02-22 Sat	22	—	unknown	04:55–05:35 (good, 0.67 h)	87.3° 11:10	9.96	2%	53.5°
2031-02-23 Sun	23	—	unknown	04:50–05:35 (good, 0.75 h)	87.3° 11:05	9.92	7%	56.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-01-25&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.