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: 02-27 (20), 02-25 (19), 02-26 (19), 02-23 (17), 02-24 (17) — by astronomy; check the weather when the night is within four days.

2026-01-30astronomy score per night — click a bar for that night2026-02-28

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2026-01-30 Fri	1	0	0	—	71.1° 11:40	10.82	95%	128.7°
2026-01-31 Sat	1	0	0	—	71.1° 11:35	10.79	99%	133.6°
2026-02-01 Sun	1	0	0	—	71.1° 11:35	10.76	100%	135.4°
2026-02-02 Mon	1	0	0	—	71.1° 11:30	10.72	99%	133.6°
2026-02-03 Tue	2	0	0	—	71.1° 11:25	10.69	95%	129.0°
2026-02-04 Wed	2	0	0	—	71.1° 11:20	10.66	89%	122.5°
2026-02-05 Thu	2	0	0	—	71.1° 11:15	10.62	82%	114.8°
2026-02-06 Fri	2	0	0	—	71.1° 11:15	10.59	74%	106.5°
2026-02-07 Sat	3	0	0	—	71.1° 11:10	10.55	65%	98.0°
2026-02-08 Sun	4	0	0	—	71.1° 11:05	10.51	56%	89.5°
2026-02-09 Mon	4	0	0	—	71.1° 11:00	10.48	46%	81.1°
2026-02-10 Tue	4	0	0	—	71.1° 10:55	10.44	37%	72.9°
2026-02-11 Wed	5	0	0	—	71.1° 10:55	10.4	28%	65.1°
2026-02-12 Thu	7	0	0	—	71.1° 10:50	10.36	20%	58.0°
2026-02-13 Fri	8	65	5	06:05–06:20 (marginal, 0.25 h)	71.1° 10:45	10.32	13%	51.8°
2026-02-14 Sat	8	0	0	—	71.1° 10:40	10.29	7%	47.2°
2026-02-15 Sun	9	90	8	05:10–05:45 (marginal, 0.58 h)	71.1° 10:35	10.25	3%	44.8°
2026-02-16 Mon	11	0	0	—	71.1° 10:35	10.21	0%	45.2°
2026-02-17 Tue	11	0	0	—	71.1° 10:30	10.17	0%	48.5°
2026-02-18 Wed	12	100	12	05:25–05:40 (good, 0.25 h)	71.1° 10:25	10.12	2%	54.3°
2026-02-19 Thu	13	0	0	—	71.1° 10:20	10.08	7%	61.9°
2026-02-20 Fri	14	0	0	—	71.1° 10:20	10.04	14%	70.8°
2026-02-21 Sat	15	0	0	—	71.1° 10:15	10.0	22%	80.4°
2026-02-22 Sun	16	2	0	—	71.1° 10:10	9.96	32%	90.3°
2026-02-23 Mon	17	31	5	05:15–05:35 (marginal, 0.33 h)	71.1° 10:05	9.91	43%	100.3°
2026-02-24 Tue	17	4	1	—	71.1° 10:00	9.87	55%	110.0°
2026-02-25 Wed	19	0	0	—	71.1° 10:00	9.83	66%	118.9°
2026-02-26 Thu	19	57	11	04:35–05:30 (marginal, 0.92 h)	71.1° 09:55	9.78	76%	126.6°
2026-02-27 Fri	20	94	19	05:05–05:30 (good, 0.42 h)	71.1° 09:50	9.74	85%	132.3°
2026-02-28 Sat	17	100	17	04:55–05:25 (good, 0.5 h)	71.1° 09:45	9.69	92%	135.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-01-30&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.