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 Vega: 01-23 (33), 01-24 (33), 01-25 (33), 01-22 (31), 01-20 (30) — by astronomy; check the weather when the night is within four days.

2040-01-04astronomy score per night — click a bar for that night2040-02-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-01-04 Wed	8	—	unknown	05:35–06:10 (marginal, 0.58 h)	87.1° 12:05	11.42	75%	99.5°
2040-01-05 Thu	8	—	unknown	05:30–06:10 (marginal, 0.67 h)	87.1° 12:00	11.41	66%	94.1°
2040-01-06 Fri	9	—	unknown	05:25–06:10 (marginal, 0.75 h)	87.1° 11:55	11.39	56%	88.5°
2040-01-07 Sat	10	—	unknown	05:25–06:45 (marginal, 1.33 h)	87.1° 11:50	11.38	45%	82.8°
2040-01-08 Sun	12	—	unknown	06:05–06:10 (good, 0.08 h)	87.1° 11:45	11.36	34%	77.3°
2040-01-09 Mon	14	—	unknown	05:55–06:10 (good, 0.25 h)	87.1° 11:40	11.35	24%	72.3°
2040-01-10 Tue	16	—	unknown	05:45–06:10 (good, 0.42 h)	87.1° 11:35	11.33	15%	68.1°
2040-01-11 Wed	19	—	unknown	05:40–06:10 (good, 0.5 h)	87.1° 11:35	11.31	7%	65.3°
2040-01-12 Thu	20	—	unknown	05:35–06:10 (good, 0.58 h)	87.1° 11:30	11.29	2%	64.2°
2040-01-13 Fri	21	—	unknown	05:30–06:10 (good, 0.67 h)	87.1° 11:25	11.27	0%	65.1°
2040-01-14 Sat	23	—	unknown	05:25–06:10 (good, 0.75 h)	87.1° 11:20	11.25	1%	67.7°
2040-01-15 Sun	24	—	unknown	05:25–06:10 (good, 0.75 h)	87.1° 11:20	11.23	5%	71.8°
2040-01-16 Mon	24	—	unknown	05:20–06:10 (good, 0.83 h)	87.1° 11:15	11.21	11%	76.9°
2040-01-17 Tue	25	—	unknown	05:15–06:10 (good, 0.92 h)	87.1° 11:10	11.19	19%	82.6°
2040-01-18 Wed	27	—	unknown	05:10–06:10 (good, 1.0 h)	87.1° 11:05	11.17	28%	88.4°
2040-01-19 Thu	28	—	unknown	05:10–06:10 (good, 1.0 h)	87.1° 11:00	11.14	38%	94.1°
2040-01-20 Fri	30	—	unknown	05:05–06:10 (good, 1.08 h)	87.1° 11:00	11.12	48%	99.4°
2040-01-21 Sat	30	—	unknown	05:00–06:05 (good, 1.08 h)	87.1° 10:55	11.09	58%	104.2°
2040-01-22 Sun	31	—	unknown	04:55–06:05 (good, 1.17 h)	87.1° 10:50	11.07	68%	108.4°
2040-01-23 Mon	33	—	unknown	04:50–06:05 (good, 1.25 h)	87.1° 10:45	11.04	76%	111.7°
2040-01-24 Tue	33	—	unknown	04:50–06:05 (good, 1.25 h)	87.1° 10:40	11.01	84%	114.2°
2040-01-25 Wed	33	—	unknown	04:55–06:05 (good, 1.17 h)	87.1° 10:40	10.98	90%	115.5°
2040-01-26 Thu	29	—	unknown	04:50–06:05 (good, 1.25 h)	87.1° 10:35	10.96	95%	115.7°
2040-01-27 Fri	29	—	unknown	04:50–06:05 (good, 1.25 h)	87.1° 10:30	10.93	98%	114.7°
2040-01-28 Sat	28	—	unknown	04:50–06:05 (good, 1.25 h)	87.1° 10:25	10.9	100%	112.6°
2040-01-29 Sun	27	—	unknown	04:50–06:00 (good, 1.17 h)	87.1° 10:25	10.87	100%	109.5°
2040-01-30 Mon	26	—	unknown	04:50–06:00 (good, 1.17 h)	87.1° 10:20	10.83	97%	105.5°
2040-01-31 Tue	25	—	unknown	04:50–06:00 (good, 1.17 h)	87.1° 10:15	10.8	93%	100.8°
2040-02-01 Wed	25	—	unknown	04:55–06:00 (good, 1.08 h)	87.1° 10:10	10.77	88%	95.5°
2040-02-02 Thu	25	—	unknown	04:50–06:00 (good, 1.17 h)	87.1° 10:05	10.74	80%	90.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-01-04&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.