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 HD 189733: 01-04 (5), 01-05 (3), 01-06 (3), 01-07 (2), 01-08 (1) — 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	5	—	unknown	18:10–18:35 (marginal, 0.42 h)	71.1° 13:30	11.42	8%	69.1°
2027-01-05 Tue	3	—	unknown	18:15–18:30 (marginal, 0.25 h)	71.1° 13:25	11.41	3%	61.3°
2027-01-06 Wed	3	—	unknown	18:15–18:25 (marginal, 0.17 h)	71.1° 13:20	11.39	1%	54.4°
2027-01-07 Thu	2	—	unknown	18:15–18:20 (marginal, 0.08 h)	71.1° 13:15	11.38	0%	48.6°
2027-01-08 Fri	1	—	unknown	18:15–18:20 (marginal, 0.08 h)	71.1° 13:10	11.36	1%	44.7°
2027-01-09 Sat	1	—	unknown	—	71.1° 13:10	11.35	4%	43.1°
2027-01-10 Sun	1	—	unknown	—	71.1° 13:05	11.33	8%	44.0°
2027-01-11 Mon	1	—	unknown	—	71.1° 13:00	11.31	14%	47.5°
2027-01-12 Tue	0	—	unknown	—	71.1° 12:55	11.29	22%	53.1°
2027-01-13 Wed	0	—	unknown	—	71.1° 12:50	11.27	31%	60.3°
2027-01-14 Thu	0	—	unknown	—	71.1° 12:50	11.25	40%	68.6°
2027-01-15 Fri	0	—	unknown	—	71.1° 12:45	11.23	51%	77.7°
2027-01-16 Sat	0	—	unknown	—	71.1° 12:40	11.21	62%	87.5°
2027-01-17 Sun	0	—	unknown	—	71.1° 12:35	11.19	72%	97.6°
2027-01-18 Mon	0	—	unknown	—	71.1° 12:30	11.16	82%	107.9°
2027-01-19 Tue	0	—	unknown	—	71.1° 12:30	11.14	90%	117.8°
2027-01-20 Wed	0	—	unknown	—	71.1° 12:25	11.11	96%	126.6°
2027-01-21 Thu	0	—	unknown	—	71.1° 12:20	11.09	100%	133.4°
2027-01-22 Fri	0	—	unknown	—	71.1° 12:15	11.06	100%	136.7°
2027-01-23 Sat	0	—	unknown	—	71.1° 12:15	11.04	97%	136.0°
2027-01-24 Sun	0	—	unknown	—	71.1° 12:10	11.01	92%	131.5°
2027-01-25 Mon	0	—	unknown	—	71.1° 12:05	10.98	84%	124.5°
2027-01-26 Tue	0	—	unknown	—	71.1° 12:00	10.95	75%	116.0°
2027-01-27 Wed	0	—	unknown	—	71.1° 11:55	10.92	65%	107.0°
2027-01-28 Thu	1	—	unknown	—	71.1° 11:50	10.89	55%	97.8°
2027-01-29 Fri	1	—	unknown	—	71.1° 11:45	10.86	45%	88.7°
2027-01-30 Sat	1	—	unknown	—	71.1° 11:40	10.83	36%	79.8°
2027-01-31 Sun	1	—	unknown	—	71.1° 11:35	10.8	27%	71.2°
2027-02-01 Mon	1	—	unknown	—	71.1° 11:35	10.77	19%	63.3°
2027-02-02 Tue	1	—	unknown	—	71.1° 11:30	10.73	12%	56.1°

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.