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: 12-19 (17), 12-20 (14), 12-25 (14), 12-26 (14), 12-27 (14) — by astronomy; check the weather when the night is within four days.

2042-12-19astronomy score per night — click a bar for that night2043-01-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-12-19 Fri	17	—	unknown	18:35–19:10 (good, 0.58 h)	71.1° 14:30	11.51	49%	61.6°
2042-12-20 Sat	14	—	unknown	18:35–18:45 (good, 0.17 h)	71.1° 14:25	11.51	60%	70.0°
2042-12-21 Sun	13	—	unknown	18:35–19:55 (marginal, 1.33 h)	71.1° 14:25	11.51	71%	79.4°
2042-12-22 Mon	12	—	unknown	18:05–19:50 (marginal, 1.75 h)	71.1° 14:20	11.51	81%	89.2°
2042-12-23 Tue	12	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 14:15	11.51	89%	99.2°
2042-12-24 Wed	13	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 14:10	11.5	95%	108.8°
2042-12-25 Thu	14	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 14:05	11.5	99%	117.7°
2042-12-26 Fri	14	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 14:05	11.5	100%	125.1°
2042-12-27 Sat	14	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 14:00	11.49	98%	130.5°
2042-12-28 Sun	14	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 13:55	11.48	94%	133.1°
2042-12-29 Mon	12	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 13:50	11.48	88%	132.8°
2042-12-30 Tue	11	—	unknown	18:40–18:55 (good, 0.25 h)	71.1° 13:45	11.47	80%	129.8°
2042-12-31 Wed	9	—	unknown	18:45–18:50 (good, 0.08 h)	71.1° 13:45	11.46	72%	124.8°
2043-01-01 Thu	8	—	unknown	18:10–19:15 (marginal, 1.08 h)	71.1° 13:40	11.45	62%	118.5°
2043-01-02 Fri	7	—	unknown	18:45–19:10 (marginal, 0.42 h)	71.1° 13:35	11.44	53%	111.3°
2043-01-03 Sat	6	—	unknown	18:10–18:40 (marginal, 0.5 h)	71.1° 13:30	11.43	44%	103.7°
2043-01-04 Sun	5	—	unknown	18:10–18:35 (marginal, 0.42 h)	71.1° 13:30	11.42	34%	95.7°
2043-01-05 Mon	3	—	unknown	18:15–18:30 (marginal, 0.25 h)	71.1° 13:25	11.4	26%	87.6°
2043-01-06 Tue	3	—	unknown	18:15–18:25 (marginal, 0.17 h)	71.1° 13:20	11.39	18%	79.4°
2043-01-07 Wed	2	—	unknown	18:15–18:20 (marginal, 0.08 h)	71.1° 13:15	11.38	11%	71.5°
2043-01-08 Thu	1	—	unknown	18:15–18:20 (marginal, 0.08 h)	71.1° 13:10	11.36	6%	63.9°
2043-01-09 Fri	1	—	unknown	—	71.1° 13:10	11.34	2%	57.0°
2043-01-10 Sat	1	—	unknown	—	71.1° 13:05	11.33	0%	51.4°
2043-01-11 Sun	1	—	unknown	—	71.1° 13:00	11.31	1%	47.7°
2043-01-12 Mon	1	—	unknown	—	71.1° 12:55	11.29	3%	46.6°
2043-01-13 Tue	0	—	unknown	—	71.1° 12:50	11.27	8%	48.5°
2043-01-14 Wed	0	—	unknown	—	71.1° 12:50	11.25	15%	53.1°
2043-01-15 Thu	0	—	unknown	—	71.1° 12:45	11.23	24%	59.8°
2043-01-16 Fri	0	—	unknown	—	71.1° 12:40	11.21	34%	67.9°
2043-01-17 Sat	0	—	unknown	—	71.1° 12:35	11.18	45%	77.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-12-19&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.