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 North America Nebula: 02-17 (18), 02-18 (18), 02-16 (16), 01-20 (15), 02-15 (15) — by astronomy; check the weather when the night is within four days.

2040-01-20astronomy score per night — click a bar for that night2040-02-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-01-20 Fri	15	—	unknown	19:00–19:15 (good, 0.25 h)	87.2° 13:25	11.12	48%	72.6°
2040-01-21 Sat	13	—	unknown	19:00–19:05 (good, 0.08 h)	87.2° 13:20	11.09	58%	77.5°
2040-01-22 Sun	12	—	unknown	19:05–20:10 (marginal, 1.08 h)	87.2° 13:15	11.07	68%	82.7°
2040-01-23 Mon	11	—	unknown	19:05–20:05 (marginal, 1.0 h)	87.2° 13:10	11.04	76%	88.1°
2040-01-24 Tue	10	—	unknown	19:05–20:00 (marginal, 0.92 h)	87.2° 13:10	11.01	84%	93.6°
2040-01-25 Wed	10	—	unknown	19:05–20:00 (marginal, 0.92 h)	87.2° 13:05	10.98	90%	98.9°
2040-01-26 Thu	10	—	unknown	19:05–19:55 (marginal, 0.83 h)	87.2° 13:00	10.96	95%	103.9°
2040-01-27 Fri	9	—	unknown	19:10–19:50 (marginal, 0.67 h)	87.2° 12:55	10.93	98%	108.4°
2040-01-28 Sat	9	—	unknown	19:10–19:45 (marginal, 0.58 h)	87.2° 12:50	10.9	100%	112.2°
2040-01-29 Sun	9	—	unknown	19:10–19:45 (marginal, 0.58 h)	87.2° 12:50	10.87	100%	115.2°
2040-01-30 Mon	9	—	unknown	19:10–19:40 (marginal, 0.5 h)	87.2° 12:45	10.83	97%	117.0°
2040-01-31 Tue	9	—	unknown	19:15–19:35 (marginal, 0.33 h)	87.2° 12:40	10.8	93%	117.4°
2040-02-01 Wed	8	—	unknown	05:40–06:00 (marginal, 0.33 h)	87.2° 12:35	10.77	88%	116.5°
2040-02-02 Thu	7	—	unknown	05:40–06:00 (marginal, 0.33 h)	87.2° 12:30	10.74	80%	114.1°
2040-02-03 Fri	7	—	unknown	05:35–06:00 (marginal, 0.42 h)	87.2° 12:30	10.7	71%	110.5°
2040-02-04 Sat	7	—	unknown	05:30–05:55 (marginal, 0.42 h)	87.2° 12:25	10.67	61%	105.8°
2040-02-05 Sun	7	—	unknown	05:25–05:55 (marginal, 0.5 h)	87.2° 12:20	10.64	50%	100.2°
2040-02-06 Mon	8	—	unknown	05:20–05:55 (marginal, 0.58 h)	87.2° 12:15	10.6	39%	94.0°
2040-02-07 Tue	9	—	unknown	05:20–05:55 (marginal, 0.58 h)	87.2° 12:15	10.56	28%	87.5°
2040-02-08 Wed	10	—	unknown	05:15–06:25 (marginal, 1.17 h)	87.2° 12:10	10.53	18%	80.9°
2040-02-09 Thu	11	—	unknown	05:45–05:50 (good, 0.08 h)	87.2° 12:05	10.49	10%	74.8°
2040-02-10 Fri	12	—	unknown	05:40–05:50 (good, 0.17 h)	87.2° 12:00	10.45	4%	69.4°
2040-02-11 Sat	12	—	unknown	05:40–05:50 (good, 0.17 h)	87.2° 11:55	10.42	1%	65.4°
2040-02-12 Sun	13	—	unknown	05:35–05:50 (good, 0.25 h)	87.2° 11:50	10.38	0%	63.1°
2040-02-13 Mon	14	—	unknown	05:30–05:50 (good, 0.33 h)	87.2° 11:45	10.34	3%	62.6°
2040-02-14 Tue	14	—	unknown	05:25–05:45 (good, 0.33 h)	87.2° 11:40	10.3	7%	63.9°
2040-02-15 Wed	15	—	unknown	05:20–05:45 (good, 0.42 h)	87.2° 11:35	10.26	14%	66.8°
2040-02-16 Thu	16	—	unknown	05:20–05:45 (good, 0.42 h)	87.2° 11:35	10.22	22%	70.8°
2040-02-17 Fri	18	—	unknown	05:15–05:45 (good, 0.5 h)	87.2° 11:30	10.18	31%	75.5°
2040-02-18 Sat	18	—	unknown	05:10–05:40 (good, 0.5 h)	87.2° 11:25	10.14	41%	80.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-01-20&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.