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: 02-21 (15), 02-20 (14), 02-19 (13), 02-18 (12), 02-16 (11) — by astronomy; check the weather when the night is within four days.

2026-01-23astronomy score per night — click a bar for that night2026-02-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2026-01-23 Fri	0	21	0	—	71.1° 12:10	11.03	26%	64.1°
2026-01-24 Sat	0	0	0	—	71.1° 12:10	11.0	36%	73.0°
2026-01-25 Sun	0	0	0	—	71.1° 12:00	10.97	47%	82.6°
2026-01-26 Mon	0	0	0	—	71.1° 12:00	10.94	58%	92.6°
2026-01-27 Tue	1	62	1	—	71.1° 11:50	10.91	69%	102.7°
2026-01-28 Wed	1	0	0	—	71.1° 11:50	10.88	80%	112.4°
2026-01-29 Thu	1	0	0	—	71.1° 11:45	10.85	88%	121.3°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-01-23&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.