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: 05-02 (76), 05-01 (71), 04-30 (66), 04-29 (60), 04-14 (57) — by astronomy; check the weather when the night is within four days.

2027-04-03astronomy score per night — click a bar for that night2027-05-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-04-03 Sat	48	—	unknown	03:30–05:25 (good, 1.92 h)	71.1° 08:35	7.99	10%	48.1°
2027-04-04 Sun	49	—	unknown	03:30–05:25 (good, 1.92 h)	71.1° 08:30	7.93	5%	54.1°
2027-04-05 Mon	49	—	unknown	03:25–05:20 (good, 1.92 h)	71.1° 08:25	7.87	1%	61.7°
2027-04-06 Tue	50	—	unknown	03:20–05:20 (good, 2.0 h)	71.1° 08:20	7.82	0%	70.5°
2027-04-07 Wed	52	—	unknown	03:15–05:20 (good, 2.08 h)	71.1° 08:20	7.76	1%	80.0°
2027-04-08 Thu	52	—	unknown	03:15–05:15 (good, 2.0 h)	71.1° 08:15	7.71	5%	89.9°
2027-04-09 Fri	54	—	unknown	03:10–05:15 (good, 2.08 h)	71.1° 08:10	7.65	10%	100.0°
2027-04-10 Sat	53	—	unknown	03:05–05:10 (good, 2.08 h)	71.1° 08:05	7.59	18%	109.9°
2027-04-11 Sun	55	—	unknown	03:00–05:10 (good, 2.17 h)	71.1° 08:00	7.54	28%	119.2°
2027-04-12 Mon	56	—	unknown	02:55–05:10 (good, 2.25 h)	71.1° 08:00	7.48	38%	127.4°
2027-04-13 Tue	56	—	unknown	02:55–05:05 (good, 2.17 h)	71.1° 07:55	7.42	50%	133.6°
2027-04-14 Wed	57	—	unknown	02:55–05:05 (good, 2.17 h)	71.1° 07:50	7.36	61%	136.9°
2027-04-15 Thu	56	—	unknown	02:50–05:00 (good, 2.17 h)	71.1° 07:45	7.31	72%	136.5°
2027-04-16 Fri	56	—	unknown	02:50–05:00 (good, 2.17 h)	71.1° 07:45	7.25	81%	132.7°
2027-04-17 Sat	52	—	unknown	02:45–05:00 (good, 2.25 h)	71.1° 07:40	7.19	89%	126.2°
2027-04-18 Sun	50	—	unknown	02:45–04:55 (good, 2.17 h)	71.1° 07:35	7.13	95%	118.0°
2027-04-19 Mon	46	—	unknown	02:45–04:55 (good, 2.17 h)	71.1° 07:30	7.08	99%	108.9°
2027-04-20 Tue	41	—	unknown	02:50–04:55 (good, 2.08 h)	71.1° 07:25	7.02	100%	99.3°
2027-04-21 Wed	37	—	unknown	03:00–04:50 (good, 1.83 h)	71.1° 07:25	6.96	99%	89.7°
2027-04-22 Thu	34	—	unknown	03:25–04:50 (good, 1.42 h)	71.1° 07:20	6.9	96%	80.3°
2027-04-23 Fri	32	—	unknown	03:35–04:45 (good, 1.17 h)	71.1° 07:15	6.84	90%	71.3°
2027-04-24 Sat	32	—	unknown	03:35–04:45 (good, 1.17 h)	71.1° 07:10	6.78	84%	63.0°
2027-04-25 Sun	33	—	unknown	03:10–04:45 (good, 1.58 h)	71.1° 07:05	6.73	76%	55.6°
2027-04-26 Mon	36	—	unknown	02:25–04:40 (good, 2.25 h)	71.1° 07:05	6.67	68%	49.4°
2027-04-27 Tue	49	—	unknown	02:00–04:40 (good, 2.67 h)	71.1° 07:00	6.61	59%	45.0°
2027-04-28 Wed	54	—	unknown	01:55–04:35 (good, 2.67 h)	71.1° 06:55	6.55	49%	42.9°
2027-04-29 Thu	60	—	unknown	01:50–04:35 (good, 2.75 h)	71.1° 06:50	6.49	40%	43.3°
2027-04-30 Fri	66	—	unknown	01:45–04:35 (good, 2.83 h)	71.1° 06:50	6.43	31%	46.3°
2027-05-01 Sat	71	—	unknown	01:40–04:30 (good, 2.83 h)	71.1° 06:45	6.38	22%	51.6°
2027-05-02 Sun	76	—	unknown	01:40–04:30 (good, 2.83 h)	71.1° 06:40	6.32	14%	58.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-04-03&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.