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: 01-04 (100), 01-05 (100), 01-06 (100), 01-07 (100), 01-08 (100) — by astronomy; check the weather when the night is within four days.

2027-01-04astronomy score per night — click a bar for that night2027-02-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-01-04 Mon	100	—	unknown	18:45–02:25 (good, 7.67 h)	72.5° 21:10	11.42	8%	167.0°
2027-01-05 Tue	100	—	unknown	18:45–02:20 (good, 7.58 h)	72.5° 21:10	11.41	3%	155.2°
2027-01-06 Wed	100	—	unknown	18:50–02:15 (good, 7.42 h)	72.5° 21:05	11.39	1%	143.4°
2027-01-07 Thu	100	—	unknown	18:50–02:10 (good, 7.33 h)	72.5° 21:00	11.38	0%	131.5°
2027-01-08 Fri	100	—	unknown	18:50–02:05 (good, 7.25 h)	72.5° 20:55	11.36	1%	119.7°
2027-01-09 Sat	100	—	unknown	18:50–02:05 (good, 7.25 h)	72.5° 20:55	11.35	4%	107.8°
2027-01-10 Sun	100	—	unknown	18:50–02:00 (good, 7.17 h)	72.5° 20:50	11.33	8%	95.8°
2027-01-11 Mon	100	—	unknown	18:50–01:55 (good, 7.08 h)	72.5° 20:45	11.31	14%	83.7°
2027-01-12 Tue	100	—	unknown	18:55–01:50 (good, 6.92 h)	72.5° 20:40	11.29	22%	71.4°
2027-01-13 Wed	98	—	unknown	18:55–01:50 (good, 6.92 h)	72.5° 20:35	11.27	31%	59.0°
2027-01-14 Thu	90	—	unknown	18:55–01:45 (good, 6.83 h)	72.5° 20:35	11.25	40%	46.2°
2027-01-15 Fri	81	—	unknown	18:55–01:40 (good, 6.75 h)	72.5° 20:30	11.23	51%	33.2°
2027-01-16 Sat	59	—	unknown	18:55–02:05 (marginal, 7.17 h)	72.5° 20:25	11.21	62%	19.7°
2027-01-17 Sun	40	—	unknown	19:00–01:50 (marginal, 6.83 h)	72.5° 20:20	11.19	72%	5.8°
2027-01-18 Mon	25	—	unknown	19:00–01:25 (marginal, 6.42 h)	72.5° 20:15	11.16	82%	8.7°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-01-04&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.