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: 01-03 (4), 01-04 (3), 01-05 (3), 01-06 (2), 01-07 (1) — by astronomy; check the weather when the night is within four days.

2042-01-03astronomy score per night — click a bar for that night2042-02-01

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-01-03 Fri	4	—	unknown	18:45–19:05 (marginal, 0.33 h)	71.1° 13:30	11.43	94%	113.0°
2042-01-04 Sat	3	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:25	11.41	98%	120.5°
2042-01-05 Sun	3	—	unknown	18:45–18:55 (marginal, 0.17 h)	71.1° 13:25	11.4	100%	126.6°
2042-01-06 Mon	2	—	unknown	—	71.1° 13:20	11.39	100%	130.9°
2042-01-07 Tue	1	—	unknown	—	71.1° 13:15	11.37	97%	132.8°
2042-01-08 Wed	1	—	unknown	—	71.1° 13:10	11.36	93%	132.2°
2042-01-09 Thu	1	—	unknown	—	71.1° 13:05	11.34	88%	129.4°
2042-01-10 Fri	1	—	unknown	—	71.1° 13:05	11.32	81%	124.7°
2042-01-11 Sat	1	—	unknown	—	71.1° 13:00	11.3	73%	118.8°
2042-01-12 Sun	0	—	unknown	—	71.1° 12:55	11.28	64%	111.9°
2042-01-13 Mon	0	—	unknown	—	71.1° 12:50	11.26	55%	104.3°
2042-01-14 Tue	0	—	unknown	—	71.1° 12:45	11.24	46%	96.4°
2042-01-15 Wed	0	—	unknown	—	71.1° 12:45	11.22	36%	88.1°
2042-01-16 Thu	0	—	unknown	—	71.1° 12:40	11.2	27%	79.7°
2042-01-17 Fri	0	—	unknown	—	71.1° 12:35	11.18	18%	71.3°
2042-01-18 Sat	0	—	unknown	—	71.1° 12:30	11.15	11%	63.2°
2042-01-19 Sun	0	—	unknown	—	71.1° 12:30	11.13	5%	56.1°
2042-01-20 Mon	0	—	unknown	—	71.1° 12:25	11.1	1%	50.5°
2042-01-21 Tue	0	—	unknown	—	71.1° 12:20	11.08	0%	47.5°
2042-01-22 Wed	0	—	unknown	—	71.1° 12:15	11.05	2%	47.7°
2042-01-23 Thu	0	—	unknown	—	71.1° 12:10	11.03	6%	51.3°
2042-01-24 Fri	0	—	unknown	—	71.1° 12:10	11.0	13%	57.5°
2042-01-25 Sat	0	—	unknown	—	71.1° 12:00	10.97	22%	65.5°
2042-01-26 Sun	0	—	unknown	—	71.1° 12:00	10.94	32%	74.5°
2042-01-27 Mon	1	—	unknown	—	71.1° 11:50	10.91	43%	83.9°
2042-01-28 Tue	1	—	unknown	—	71.1° 11:50	10.88	55%	93.3°
2042-01-29 Wed	1	—	unknown	—	71.1° 11:45	10.85	65%	102.4°
2042-01-30 Thu	1	—	unknown	—	71.1° 11:40	10.82	75%	111.0°
2042-01-31 Fri	1	—	unknown	—	71.1° 11:35	10.79	83%	118.6°
2042-02-01 Sat	1	—	unknown	—	71.1° 11:35	10.75	90%	125.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-01-03&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.