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: 05-15 (82), 05-14 (74), 04-30 (73), 05-02 (73), 05-03 (73) — by astronomy; check the weather when the night is within four days.

2039-04-16astronomy score per night — click a bar for that night2039-05-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-04-16 Sat	52	—	unknown	02:40–05:00 (good, 2.33 h)	71.1° 07:45	7.24	37%	46.0°
2039-04-17 Sun	59	—	unknown	02:35–05:00 (good, 2.42 h)	71.1° 07:40	7.19	27%	48.8°
2039-04-18 Mon	61	—	unknown	02:35–04:55 (good, 2.33 h)	71.1° 07:35	7.13	19%	53.9°
2039-04-19 Tue	62	—	unknown	02:30–04:55 (good, 2.42 h)	71.1° 07:30	7.07	12%	60.5°
2039-04-20 Wed	64	—	unknown	02:25–04:55 (good, 2.5 h)	71.1° 07:25	7.01	6%	68.1°
2039-04-21 Thu	64	—	unknown	02:20–04:50 (good, 2.5 h)	71.1° 07:25	6.95	2%	76.2°
2039-04-22 Fri	65	—	unknown	02:20–04:50 (good, 2.5 h)	71.1° 07:20	6.9	0%	84.5°
2039-04-23 Sat	66	—	unknown	02:15–04:45 (good, 2.5 h)	71.1° 07:15	6.84	0%	92.9°
2039-04-24 Sun	67	—	unknown	02:10–04:45 (good, 2.58 h)	71.1° 07:10	6.78	2%	101.2°
2039-04-25 Mon	69	—	unknown	02:05–04:45 (good, 2.67 h)	71.1° 07:05	6.72	6%	109.1°
2039-04-26 Tue	69	—	unknown	02:00–04:40 (good, 2.67 h)	71.1° 07:05	6.66	11%	116.5°
2039-04-27 Wed	71	—	unknown	02:00–04:40 (good, 2.67 h)	71.1° 07:00	6.6	17%	123.2°
2039-04-28 Thu	71	—	unknown	01:55–04:35 (good, 2.67 h)	71.1° 06:55	6.55	25%	128.6°
2039-04-29 Fri	72	—	unknown	01:55–04:35 (good, 2.67 h)	71.1° 06:50	6.49	34%	132.5°
2039-04-30 Sat	73	—	unknown	01:50–04:35 (good, 2.75 h)	71.1° 06:50	6.43	43%	134.2°
2039-05-01 Sun	72	—	unknown	01:45–04:30 (good, 2.75 h)	71.1° 06:45	6.37	53%	133.3°
2039-05-02 Mon	73	—	unknown	01:45–04:30 (good, 2.75 h)	71.1° 06:40	6.31	64%	129.9°
2039-05-03 Tue	73	—	unknown	01:40–04:30 (good, 2.83 h)	71.1° 06:35	6.26	74%	124.1°
2039-05-04 Wed	64	—	unknown	01:40–04:25 (good, 2.75 h)	71.1° 06:30	6.2	83%	116.4°
2039-05-05 Thu	58	—	unknown	01:45–04:25 (good, 2.67 h)	71.1° 06:30	6.14	91%	107.4°
2039-05-06 Fri	50	—	unknown	01:50–04:20 (good, 2.5 h)	71.1° 06:25	6.08	96%	97.5°
2039-05-07 Sat	43	—	unknown	02:30–04:20 (good, 1.83 h)	71.1° 06:20	6.03	100%	87.1°
2039-05-08 Sun	37	—	unknown	03:10–04:20 (good, 1.17 h)	71.1° 06:15	5.97	100%	76.6°
2039-05-09 Mon	33	—	unknown	03:45–04:15 (good, 0.5 h)	71.1° 06:10	5.91	97%	66.7°
2039-05-10 Tue	33	—	unknown	03:55–04:15 (good, 0.33 h)	71.1° 06:10	5.86	91%	57.9°
2039-05-11 Wed	36	—	unknown	03:20–04:15 (good, 0.92 h)	71.1° 06:05	5.8	83%	51.1°
2039-05-12 Thu	50	—	unknown	01:00–04:10 (good, 3.17 h)	71.1° 06:00	5.75	74%	46.9°
2039-05-13 Fri	64	—	unknown	00:55–04:10 (good, 3.25 h)	71.1° 05:55	5.69	63%	45.9°
2039-05-14 Sat	74	—	unknown	00:50–04:10 (good, 3.33 h)	71.1° 05:55	5.64	52%	48.1°
2039-05-15 Sun	82	—	unknown	00:45–04:05 (good, 3.33 h)	71.1° 05:50	5.59	42%	52.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-04-16&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.