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: 04-14 (57), 04-12 (56), 04-13 (56), 04-11 (55), 04-09 (54) — by astronomy; check the weather when the night is within four days.

2027-03-16astronomy score per night — click a bar for that night2027-04-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-03-16 Tue	34	—	unknown	03:45–05:00 (good, 1.25 h)	71.1° 08:45	8.94	64%	128.8°
2027-03-17 Wed	34	—	unknown	03:45–05:00 (good, 1.25 h)	71.1° 08:40	8.89	75%	134.5°
2027-03-18 Thu	33	—	unknown	03:40–04:55 (good, 1.25 h)	71.1° 08:35	8.84	84%	137.0°
2027-03-19 Fri	31	—	unknown	03:40–04:55 (good, 1.25 h)	71.1° 08:35	8.79	92%	135.6°
2027-03-20 Sat	30	—	unknown	03:35–04:55 (good, 1.33 h)	71.1° 08:30	8.73	97%	130.8°
2027-03-21 Sun	30	—	unknown	03:35–04:50 (good, 1.25 h)	71.1° 08:25	8.68	100%	123.5°
2027-03-22 Mon	29	—	unknown	03:35–04:50 (good, 1.25 h)	71.1° 08:20	8.63	100%	114.8°
2027-03-23 Tue	26	—	unknown	03:35–04:45 (good, 1.17 h)	71.1° 08:15	8.58	97%	105.3°
2027-03-24 Wed	25	—	unknown	03:35–04:45 (good, 1.17 h)	71.1° 08:15	8.53	92%	95.7°
2027-03-25 Thu	24	—	unknown	03:35–04:45 (good, 1.17 h)	71.1° 08:10	8.47	86%	86.1°
2027-03-26 Fri	23	—	unknown	03:30–04:40 (good, 1.17 h)	71.1° 08:05	8.42	78%	77.0°
2027-03-27 Sat	24	—	unknown	04:25–05:40 (good, 1.25 h)	71.1° 09:00	8.37	70%	68.3°
2027-03-28 Sun	26	—	unknown	04:20–05:40 (good, 1.33 h)	71.1° 08:55	8.31	60%	60.4°
2027-03-29 Mon	28	—	unknown	04:10–05:35 (good, 1.42 h)	71.1° 08:55	8.26	51%	53.5°
2027-03-30 Tue	33	—	unknown	03:50–05:35 (good, 1.75 h)	71.1° 08:50	8.2	42%	47.9°
2027-03-31 Wed	39	—	unknown	03:45–05:30 (good, 1.75 h)	71.1° 08:45	8.15	32%	44.2°
2027-04-01 Thu	43	—	unknown	03:40–05:30 (good, 1.83 h)	71.1° 08:40	8.1	24%	42.9°
2027-04-02 Fri	46	—	unknown	03:35–05:30 (good, 1.92 h)	71.1° 08:40	8.04	16%	44.3°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-03-16&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.