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: 12-29 (100), 12-30 (100), 12-31 (100), 01-01 (100), 01-02 (100) — by astronomy; check the weather when the night is within four days.

2042-12-21astronomy score per night — click a bar for that night2043-01-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-12-21 Sun	82	—	unknown	23:55–02:30 (good, 2.58 h)	72.5° 22:10	11.51	71%	34.7°
2042-12-22 Mon	49	—	unknown	18:35–03:35 (marginal, 9.0 h)	72.6° 22:05	11.51	81%	20.2°
2042-12-23 Tue	31	—	unknown	18:40–03:15 (marginal, 8.58 h)	72.6° 22:00	11.51	89%	5.6°
2042-12-24 Wed	21	—	unknown	18:40–20:05 (marginal, 1.42 h)	72.5° 21:55	11.5	95%	9.0°
2042-12-25 Thu	21	—	unknown	18:40–20:25 (marginal, 1.75 h)	72.5° 21:50	11.5	99%	23.6°
2042-12-26 Fri	33	—	unknown	18:40–22:35 (marginal, 3.92 h)	72.5° 21:50	11.5	100%	38.0°
2042-12-27 Sat	57	—	unknown	18:40–02:30 (marginal, 7.83 h)	72.6° 21:45	11.49	98%	52.1°
2042-12-28 Sun	93	—	unknown	18:40–22:15 (good, 3.58 h)	72.6° 21:40	11.48	94%	65.8°
2042-12-29 Mon	100	—	unknown	18:40–00:45 (good, 6.08 h)	72.5° 21:35	11.48	88%	79.2°
2042-12-30 Tue	100	—	unknown	18:40–02:10 (good, 7.5 h)	72.5° 21:35	11.47	80%	92.1°
2042-12-31 Wed	100	—	unknown	18:45–02:25 (good, 7.67 h)	72.5° 21:30	11.46	72%	104.7°
2043-01-01 Thu	100	—	unknown	18:45–02:30 (good, 7.75 h)	72.6° 21:25	11.45	62%	117.0°
2043-01-02 Fri	100	—	unknown	18:45–02:25 (good, 7.67 h)	72.6° 21:20	11.44	53%	129.0°
2043-01-03 Sat	100	—	unknown	18:45–02:25 (good, 7.67 h)	72.5° 21:15	11.43	44%	140.9°
2043-01-04 Sun	100	—	unknown	18:45–02:25 (good, 7.67 h)	72.5° 21:15	11.42	34%	152.7°
2043-01-05 Mon	100	—	unknown	18:45–02:20 (good, 7.58 h)	72.6° 21:10	11.4	26%	164.6°
2043-01-06 Tue	100	—	unknown	18:50–02:15 (good, 7.42 h)	72.6° 21:05	11.39	18%	176.5°
2043-01-07 Wed	100	—	unknown	18:50–02:10 (good, 7.33 h)	72.6° 21:00	11.38	11%	171.3°
2043-01-08 Thu	100	—	unknown	18:50–02:10 (good, 7.33 h)	72.5° 20:55	11.36	6%	159.0°
2043-01-09 Fri	100	—	unknown	18:50–02:05 (good, 7.25 h)	72.5° 20:55	11.34	2%	146.4°
2043-01-10 Sat	100	—	unknown	18:50–02:00 (good, 7.17 h)	72.6° 20:50	11.33	0%	133.6°
2043-01-11 Sun	100	—	unknown	18:50–01:55 (good, 7.08 h)	72.6° 20:45	11.31	1%	120.4°
2043-01-12 Mon	100	—	unknown	18:55–01:50 (good, 6.92 h)	72.5° 20:40	11.29	3%	107.1°
2043-01-13 Tue	100	—	unknown	18:55–01:50 (good, 6.92 h)	72.5° 20:35	11.27	8%	93.5°
2043-01-14 Wed	100	—	unknown	18:55–01:45 (good, 6.83 h)	72.5° 20:35	11.25	15%	79.8°
2043-01-15 Thu	100	—	unknown	18:55–01:40 (good, 6.75 h)	72.6° 20:30	11.23	24%	65.9°
2043-01-16 Fri	95	—	unknown	18:55–01:35 (good, 6.67 h)	72.6° 20:25	11.21	34%	52.0°
2043-01-17 Sat	85	—	unknown	19:00–01:35 (good, 6.58 h)	72.5° 20:20	11.18	45%	37.9°
2043-01-18 Sun	64	—	unknown	20:45–01:00 (good, 4.25 h)	72.5° 20:20	11.16	56%	23.8°
2043-01-19 Mon	47	—	unknown	19:00–01:45 (marginal, 6.75 h)	72.6° 20:15	11.14	67%	9.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-12-21&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.