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: 03-18 (35), 03-17 (33), 03-16 (29), 03-15 (24), 02-27 (21) — by astronomy; check the weather when the night is within four days.

2042-02-17astronomy score per night — click a bar for that night2042-03-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-02-17 Mon	11	—	unknown	05:30–05:40 (good, 0.17 h)	71.1° 10:30	10.16	8%	48.5°
2042-02-18 Tue	12	—	unknown	05:25–05:40 (good, 0.25 h)	71.1° 10:25	10.12	3%	47.2°
2042-02-19 Wed	13	—	unknown	05:20–05:40 (good, 0.33 h)	71.1° 10:20	10.08	0%	49.3°
2042-02-20 Thu	14	—	unknown	05:15–05:40 (good, 0.42 h)	71.1° 10:20	10.04	1%	54.5°
2042-02-21 Fri	15	—	unknown	05:15–05:35 (good, 0.33 h)	71.1° 10:15	9.99	4%	62.1°
2042-02-22 Sat	16	—	unknown	05:10–05:35 (good, 0.42 h)	71.1° 10:10	9.95	10%	71.1°
2042-02-23 Sun	17	—	unknown	05:05–05:35 (good, 0.5 h)	71.1° 10:05	9.91	18%	80.8°
2042-02-24 Mon	17	—	unknown	05:00–05:30 (good, 0.5 h)	71.1° 10:00	9.86	28%	90.5°
2042-02-25 Tue	19	—	unknown	04:55–05:30 (good, 0.58 h)	71.1° 10:00	9.82	39%	100.0°
2042-02-26 Wed	20	—	unknown	04:55–05:30 (good, 0.58 h)	71.1° 09:55	9.78	50%	108.8°
2042-02-27 Thu	21	—	unknown	04:50–05:30 (good, 0.67 h)	71.1° 09:50	9.73	60%	116.8°
2042-02-28 Fri	21	—	unknown	04:45–05:25 (good, 0.67 h)	71.1° 09:45	9.69	70%	123.6°
2042-03-01 Sat	21	—	unknown	04:45–05:25 (good, 0.67 h)	71.1° 09:45	9.64	79%	128.7°
2042-03-02 Sun	20	—	unknown	04:45–05:25 (good, 0.67 h)	71.1° 09:40	9.6	86%	131.9°
2042-03-03 Mon	19	—	unknown	04:40–05:20 (good, 0.67 h)	71.1° 09:35	9.55	92%	132.8°
2042-03-04 Tue	20	—	unknown	04:40–05:20 (good, 0.67 h)	71.1° 09:30	9.5	97%	131.3°
2042-03-05 Wed	20	—	unknown	04:35–05:20 (good, 0.75 h)	71.1° 09:25	9.46	99%	127.7°
2042-03-06 Thu	20	—	unknown	04:35–05:15 (good, 0.67 h)	71.1° 09:25	9.41	100%	122.5°
2042-03-07 Fri	20	—	unknown	04:30–05:15 (good, 0.75 h)	71.1° 09:20	9.36	99%	116.2°
2042-03-08 Sat	19	—	unknown	04:30–05:15 (good, 0.75 h)	71.1° 09:15	9.31	96%	109.0°
2042-03-09 Sun	17	—	unknown	04:30–05:10 (good, 0.67 h)	71.1° 09:10	9.27	92%	101.3°
2042-03-10 Mon	17	—	unknown	04:30–05:10 (good, 0.67 h)	71.1° 09:05	9.22	86%	93.3°
2042-03-11 Tue	18	—	unknown	04:25–05:10 (good, 0.75 h)	71.1° 09:05	9.17	78%	85.2°
2042-03-12 Wed	18	—	unknown	04:20–05:05 (good, 0.75 h)	71.1° 09:00	9.12	70%	77.1°
2042-03-13 Thu	19	—	unknown	04:15–05:05 (good, 0.83 h)	71.1° 08:55	9.07	60%	69.2°
2042-03-14 Fri	21	—	unknown	04:05–05:05 (good, 1.0 h)	71.1° 08:50	9.02	50%	61.7°
2042-03-15 Sat	24	—	unknown	04:00–05:00 (good, 1.0 h)	71.1° 08:50	8.97	40%	55.2°
2042-03-16 Sun	29	—	unknown	03:40–05:00 (good, 1.33 h)	71.1° 08:45	8.92	30%	50.1°
2042-03-17 Mon	33	—	unknown	03:40–04:55 (good, 1.25 h)	71.1° 08:40	8.87	20%	47.5°
2042-03-18 Tue	35	—	unknown	03:35–04:55 (good, 1.33 h)	71.1° 08:35	8.82	11%	48.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-02-17&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.