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: 04-16 (61), 04-17 (61), 04-18 (61), 04-14 (59), 04-15 (59) — by astronomy; check the weather when the night is within four days.

2040-03-20astronomy score per night — click a bar for that night2040-04-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-03-20 Tue	37	—	unknown	03:25–04:50 (good, 1.42 h)	71.1° 08:25	8.69	52%	125.0°
2040-03-21 Wed	38	—	unknown	03:20–04:50 (good, 1.5 h)	71.1° 08:20	8.64	61%	129.7°
2040-03-22 Thu	37	—	unknown	03:20–04:45 (good, 1.42 h)	71.1° 08:20	8.59	70%	132.6°
2040-03-23 Fri	37	—	unknown	03:20–04:45 (good, 1.42 h)	71.1° 08:15	8.53	78%	133.3°
2040-03-24 Sat	35	—	unknown	04:15–05:45 (good, 1.5 h)	71.1° 09:10	8.48	86%	131.7°
2040-03-25 Sun	33	—	unknown	04:15–05:40 (good, 1.42 h)	71.1° 09:05	8.43	92%	127.7°
2040-03-26 Mon	34	—	unknown	04:10–05:40 (good, 1.5 h)	71.1° 09:00	8.37	97%	121.9°
2040-03-27 Tue	32	—	unknown	04:10–05:40 (good, 1.5 h)	71.1° 09:00	8.32	99%	114.6°
2040-03-28 Wed	29	—	unknown	04:15–05:35 (good, 1.33 h)	71.1° 08:55	8.27	100%	106.2°
2040-03-29 Thu	26	—	unknown	04:15–05:35 (good, 1.33 h)	71.1° 08:50	8.21	98%	97.1°
2040-03-30 Fri	24	—	unknown	04:40–05:30 (good, 0.83 h)	71.1° 08:45	8.16	94%	87.6°
2040-03-31 Sat	23	—	unknown	04:50–05:30 (good, 0.67 h)	71.1° 08:45	8.1	87%	78.2°
2040-04-01 Sun	24	—	unknown	04:40–05:30 (good, 0.83 h)	71.1° 08:40	8.05	79%	69.0°
2040-04-02 Mon	26	—	unknown	04:05–05:25 (good, 1.33 h)	71.1° 08:35	7.99	68%	60.7°
2040-04-03 Tue	29	—	unknown	03:50–05:25 (good, 1.58 h)	71.1° 08:30	7.94	57%	53.7°
2040-04-04 Wed	35	—	unknown	03:25–05:20 (good, 1.92 h)	71.1° 08:25	7.88	46%	48.8°
2040-04-05 Thu	45	—	unknown	03:20–05:20 (good, 2.0 h)	71.1° 08:25	7.83	35%	46.8°
2040-04-06 Fri	50	—	unknown	03:20–05:20 (good, 2.0 h)	71.1° 08:20	7.77	24%	47.9°
2040-04-07 Sat	52	—	unknown	03:15–05:15 (good, 2.0 h)	71.1° 08:15	7.72	16%	52.0°
2040-04-08 Sun	53	—	unknown	03:10–05:15 (good, 2.08 h)	71.1° 08:10	7.66	8%	58.3°
2040-04-09 Mon	54	—	unknown	03:05–05:15 (good, 2.17 h)	71.1° 08:05	7.6	3%	66.0°
2040-04-10 Tue	54	—	unknown	03:00–05:10 (good, 2.17 h)	71.1° 08:05	7.55	1%	74.5°
2040-04-11 Wed	56	—	unknown	03:00–05:10 (good, 2.17 h)	71.1° 08:00	7.49	0%	83.3°
2040-04-12 Thu	57	—	unknown	02:55–05:05 (good, 2.17 h)	71.1° 07:55	7.43	2%	92.2°
2040-04-13 Fri	57	—	unknown	02:50–05:05 (good, 2.25 h)	71.1° 07:50	7.37	6%	100.8°
2040-04-14 Sat	59	—	unknown	02:45–05:05 (good, 2.33 h)	71.1° 07:50	7.32	11%	108.9°
2040-04-15 Sun	59	—	unknown	02:40–05:00 (good, 2.33 h)	71.1° 07:45	7.26	18%	116.4°
2040-04-16 Mon	61	—	unknown	02:40–05:00 (good, 2.33 h)	71.1° 07:40	7.2	26%	122.9°
2040-04-17 Tue	61	—	unknown	02:35–04:55 (good, 2.33 h)	71.1° 07:35	7.14	35%	128.1°
2040-04-18 Wed	61	—	unknown	02:35–04:55 (good, 2.33 h)	71.1° 07:30	7.08	44%	131.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-03-20&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.