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: 05-01 (75), 04-29 (74), 04-30 (73), 04-28 (72), 04-26 (71) — by astronomy; check the weather when the night is within four days.

2028-04-02astronomy score per night — click a bar for that night2028-05-01

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-04-02 Sun	47	—	unknown	03:35–05:25 (good, 1.83 h)	71.1° 08:35	8.0	51%	131.7°
2028-04-03 Mon	49	—	unknown	03:35–05:25 (good, 1.83 h)	71.1° 08:30	7.94	63%	137.0°
2028-04-04 Tue	49	—	unknown	03:30–05:25 (good, 1.92 h)	71.1° 08:25	7.89	73%	138.9°
2028-04-05 Wed	47	—	unknown	03:30–05:20 (good, 1.83 h)	71.1° 08:25	7.83	83%	136.7°
2028-04-06 Thu	44	—	unknown	03:25–05:20 (good, 1.92 h)	71.1° 08:20	7.78	91%	130.8°
2028-04-07 Fri	43	—	unknown	03:25–05:15 (good, 1.83 h)	71.1° 08:15	7.72	97%	122.4°
2028-04-08 Sat	40	—	unknown	03:25–05:15 (good, 1.83 h)	71.1° 08:10	7.66	100%	112.4°
2028-04-09 Sun	36	—	unknown	03:30–05:15 (good, 1.75 h)	71.1° 08:05	7.61	100%	101.7°
2028-04-10 Mon	31	—	unknown	03:35–05:10 (good, 1.58 h)	71.1° 08:05	7.55	97%	90.9°
2028-04-11 Tue	30	—	unknown	03:55–05:10 (good, 1.25 h)	71.1° 08:00	7.49	92%	80.4°
2028-04-12 Wed	28	—	unknown	04:05–05:05 (good, 1.0 h)	71.1° 07:55	7.44	85%	70.4°
2028-04-13 Thu	28	—	unknown	03:50–05:05 (good, 1.25 h)	71.1° 07:50	7.38	76%	61.3°
2028-04-14 Fri	31	—	unknown	03:15–05:05 (good, 1.83 h)	71.1° 07:50	7.32	67%	53.3°
2028-04-15 Sat	35	—	unknown	03:05–05:00 (good, 1.92 h)	71.1° 07:45	7.26	57%	47.0°
2028-04-16 Sun	45	—	unknown	02:40–05:00 (good, 2.33 h)	71.1° 07:40	7.21	48%	42.7°
2028-04-17 Mon	50	—	unknown	02:35–04:55 (good, 2.33 h)	71.1° 07:35	7.15	38%	41.1°
2028-04-18 Tue	55	—	unknown	02:30–04:55 (good, 2.42 h)	71.1° 07:30	7.09	29%	42.2°
2028-04-19 Wed	59	—	unknown	02:25–04:55 (good, 2.5 h)	71.1° 07:30	7.03	21%	45.9°
2028-04-20 Thu	63	—	unknown	02:25–04:50 (good, 2.42 h)	71.1° 07:25	6.97	14%	51.5°
2028-04-21 Fri	65	—	unknown	02:20–04:50 (good, 2.5 h)	71.1° 07:20	6.92	8%	58.7°
2028-04-22 Sat	65	—	unknown	02:15–04:45 (good, 2.5 h)	71.1° 07:15	6.86	4%	66.8°
2028-04-23 Sun	67	—	unknown	02:10–04:45 (good, 2.58 h)	71.1° 07:10	6.8	1%	75.7°
2028-04-24 Mon	68	—	unknown	02:05–04:45 (good, 2.67 h)	71.1° 07:10	6.74	0%	85.0°
2028-04-25 Tue	69	—	unknown	02:05–04:40 (good, 2.58 h)	71.1° 07:05	6.68	1%	94.6°
2028-04-26 Wed	71	—	unknown	02:00–04:40 (good, 2.67 h)	71.1° 07:00	6.62	5%	104.3°
2028-04-27 Thu	71	—	unknown	01:55–04:40 (good, 2.75 h)	71.1° 06:55	6.57	10%	113.7°
2028-04-28 Fri	72	—	unknown	01:50–04:35 (good, 2.75 h)	71.1° 06:50	6.51	18%	122.6°
2028-04-29 Sat	74	—	unknown	01:45–04:35 (good, 2.83 h)	71.1° 06:50	6.45	27%	130.4°
2028-04-30 Sun	73	—	unknown	01:45–04:30 (good, 2.75 h)	71.1° 06:45	6.39	37%	136.2°
2028-05-01 Mon	75	—	unknown	01:45–04:30 (good, 2.75 h)	71.1° 06:40	6.33	48%	139.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-04-02&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.