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: 03-23 (100), 03-24 (100), 04-11 (100), 04-12 (100), 04-13 (100) — by astronomy; check the weather when the night is within four days.

2026-03-20astronomy score per night — click a bar for that night2026-04-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2026-03-20 Fri	97	0	0	—	87.1° 07:05	8.72	5%	91.3°
2026-03-21 Sat	98	0	0	—	87.1° 07:00	8.67	11%	97.1°
2026-03-22 Sun	99	0	0	—	87.1° 06:55	8.62	19%	102.6°
2026-03-23 Mon	100	0	0	—	87.1° 06:50	8.57	29%	107.3°
2026-03-24 Tue	100	0	0	—	87.1° 06:50	8.51	40%	111.0°
2026-03-25 Wed	99	83	82	01:00–04:00 (good, 3.0 h)	87.1° 06:45	8.46	52%	113.3°
2026-03-26 Thu	97	3	3	—	87.1° 06:40	8.41	63%	114.2°
2026-03-27 Fri	97	16	15	02:00–03:00 (marginal, 1.0 h)	87.1° 06:35	8.35	73%	113.6°
2026-03-28 Sat	93	0	0	—	87.1° 07:30	8.3	82%	111.7°
2026-03-29 Sun	79	0	0	—	87.1° 07:30	8.25	90%	108.5°
2026-03-30 Mon	74	0	0	—	87.1° 07:25	8.19	95%	104.5°
2026-03-31 Tue	68	0	0	—	87.1° 07:20	8.14	99%	99.8°
2026-04-01 Wed	64	0	0	—	87.1° 07:15	8.08	100%	94.8°
2026-04-02 Thu	60	0	0	—	87.1° 07:15	8.03	99%	89.6°
2026-04-03 Fri	57	0	0	—	87.1° 07:10	7.97	96%	84.6°
2026-04-04 Sat	57	20	12	—	87.1° 07:05	7.92	92%	79.8°
2026-04-05 Sun	58	83	48	04:00–05:20 (good, 1.33 h)	87.1° 07:00	7.86	86%	75.5°
2026-04-06 Mon	63	94	59	01:30–05:00 (good, 3.5 h)	87.1° 06:55	7.8	79%	71.8°
2026-04-07 Tue	77	59	45	04:00–05:20 (good, 1.33 h)	87.1° 06:55	7.75	71%	68.9°
2026-04-08 Wed	87	2	1	—	87.1° 06:50	7.69	62%	66.8°
2026-04-09 Thu	94	33	31	00:20–03:00 (marginal, 2.67 h)	87.1° 06:45	7.64	53%	65.8°
2026-04-10 Fri	98	0	0	—	87.1° 06:40	7.58	43%	65.9°
2026-04-11 Sat	100	24	24	01:30–02:00 (good, 0.5 h)	87.1° 06:35	7.52	33%	67.1°
2026-04-12 Sun	100	4	4	—	87.1° 06:35	7.47	24%	69.6°
2026-04-13 Mon	100	0	0	—	87.1° 06:30	7.41	16%	73.1°
2026-04-14 Tue	100	21	21	02:00–03:00 (good, 1.0 h)	87.1° 06:25	7.35	9%	77.7°
2026-04-15 Wed	100	0	0	—	87.1° 06:20	7.29	3%	83.0°
2026-04-16 Thu	100	22	22	04:00–05:35 (marginal, 1.58 h)	87.1° 06:20	7.24	0%	88.9°
2026-04-17 Fri	100	95	95	00:25–05:00 (good, 4.58 h)	87.1° 06:15	7.18	0%	94.9°
2026-04-18 Sat	100	92	92	00:40–04:55 (good, 4.25 h)	87.1° 06:10	7.12	3%	100.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-03-20&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.