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: 04-30 (73), 05-02 (73), 04-29 (72), 05-01 (72), 04-27 (71) — by astronomy; check the weather when the night is within four days.

2039-04-03astronomy score per night — click a bar for that night2039-05-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-04-03 Sun	46	—	unknown	03:40–05:25 (good, 1.75 h)	71.1° 08:35	7.98	70%	134.4°
2039-04-04 Mon	46	—	unknown	03:35–05:25 (good, 1.83 h)	71.1° 08:30	7.93	79%	132.5°
2039-04-05 Tue	42	—	unknown	03:35–05:20 (good, 1.75 h)	71.1° 08:25	7.87	87%	128.0°
2039-04-06 Wed	41	—	unknown	03:30–05:20 (good, 1.83 h)	71.1° 08:20	7.81	93%	121.2°
2039-04-07 Thu	38	—	unknown	03:30–05:20 (good, 1.83 h)	71.1° 08:20	7.76	98%	112.7°
2039-04-08 Fri	33	—	unknown	03:35–05:15 (good, 1.67 h)	71.1° 08:15	7.7	100%	103.1°
2039-04-09 Sat	30	—	unknown	03:55–05:15 (good, 1.33 h)	71.1° 08:10	7.64	99%	92.8°
2039-04-10 Sun	26	—	unknown	04:25–05:10 (good, 0.75 h)	71.1° 08:05	7.59	95%	82.4°
2039-04-11 Mon	25	—	unknown	04:40–05:10 (good, 0.5 h)	71.1° 08:00	7.53	89%	72.3°
2039-04-12 Tue	26	—	unknown	04:30–05:10 (good, 0.67 h)	71.1° 08:00	7.47	80%	63.0°
2039-04-13 Wed	28	—	unknown	03:45–05:05 (good, 1.33 h)	71.1° 07:55	7.42	70%	55.1°
2039-04-14 Thu	34	—	unknown	03:10–05:05 (good, 1.92 h)	71.1° 07:50	7.36	59%	49.2°
2039-04-15 Fri	44	—	unknown	02:45–05:00 (good, 2.25 h)	71.1° 07:45	7.3	48%	46.1°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-04-03&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.