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: 04-02 (100), 04-03 (100), 04-04 (100), 04-05 (100), 04-06 (100) — by astronomy; check the weather when the night is within four days.

2027-04-02astronomy score per night — click a bar for that night2027-05-01

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-04-02 Fri	100	—	unknown	01:20–05:30 (good, 4.17 h)	87.1° 07:15	8.04	16%	68.2°
2027-04-03 Sat	100	—	unknown	01:15–05:25 (good, 4.17 h)	87.1° 07:10	7.99	10%	71.7°
2027-04-04 Sun	100	—	unknown	01:10–05:25 (good, 4.25 h)	87.1° 07:05	7.93	5%	76.0°
2027-04-05 Mon	100	—	unknown	01:10–05:20 (good, 4.17 h)	87.1° 07:00	7.87	1%	81.1°
2027-04-06 Tue	100	—	unknown	01:05–05:20 (good, 4.25 h)	87.1° 07:00	7.82	0%	86.6°
2027-04-07 Wed	100	—	unknown	01:00–05:20 (good, 4.33 h)	87.1° 06:55	7.76	1%	92.4°
2027-04-08 Thu	100	—	unknown	00:55–05:15 (good, 4.33 h)	87.1° 06:50	7.71	5%	98.2°
2027-04-09 Fri	100	—	unknown	00:50–05:15 (good, 4.42 h)	87.1° 06:45	7.65	10%	103.7°
2027-04-10 Sat	100	—	unknown	00:50–05:10 (good, 4.33 h)	87.1° 06:40	7.59	18%	108.6°
2027-04-11 Sun	100	—	unknown	00:45–05:10 (good, 4.42 h)	87.1° 06:40	7.54	28%	112.4°
2027-04-12 Mon	100	—	unknown	00:45–05:10 (good, 4.42 h)	87.1° 06:35	7.48	38%	114.9°
2027-04-13 Tue	100	—	unknown	00:45–05:05 (good, 4.33 h)	87.1° 06:30	7.42	50%	115.8°
2027-04-14 Wed	100	—	unknown	00:40–05:05 (good, 4.42 h)	87.1° 06:25	7.36	61%	115.1°
2027-04-15 Thu	100	—	unknown	00:40–05:00 (good, 4.33 h)	87.1° 06:25	7.31	72%	112.7°
2027-04-16 Fri	100	—	unknown	00:40–05:00 (good, 4.33 h)	87.1° 06:20	7.25	81%	109.0°
2027-04-17 Sat	88	—	unknown	00:45–05:00 (good, 4.25 h)	87.1° 06:15	7.19	89%	104.2°
2027-04-18 Sun	81	—	unknown	00:45–04:55 (good, 4.17 h)	87.1° 06:10	7.13	95%	98.8°
2027-04-19 Mon	74	—	unknown	01:10–04:55 (good, 3.75 h)	87.1° 06:05	7.08	99%	93.0°
2027-04-20 Tue	68	—	unknown	01:30–04:55 (good, 3.42 h)	87.1° 06:05	7.02	100%	87.1°
2027-04-21 Wed	64	—	unknown	01:35–04:50 (good, 3.25 h)	87.1° 06:00	6.96	99%	81.5°
2027-04-22 Thu	62	—	unknown	01:25–04:50 (good, 3.42 h)	87.1° 05:55	6.9	96%	76.4°
2027-04-23 Fri	63	—	unknown	00:40–04:45 (good, 4.08 h)	87.1° 05:50	6.84	90%	71.9°
2027-04-24 Sat	79	—	unknown	23:55–04:45 (good, 4.83 h)	87.1° 05:45	6.78	84%	68.4°
2027-04-25 Sun	87	—	unknown	23:50–04:45 (good, 4.92 h)	87.1° 05:45	6.73	76%	65.8°
2027-04-26 Mon	92	—	unknown	23:45–04:40 (good, 4.92 h)	87.1° 05:40	6.67	68%	64.4°
2027-04-27 Tue	97	—	unknown	23:40–04:40 (good, 5.0 h)	87.1° 05:35	6.61	59%	64.1°
2027-04-28 Wed	100	—	unknown	23:35–04:35 (good, 5.0 h)	87.1° 05:30	6.55	49%	65.0°
2027-04-29 Thu	100	—	unknown	23:35–04:35 (good, 5.0 h)	87.1° 05:30	6.49	40%	67.1°
2027-04-30 Fri	100	—	unknown	23:30–04:35 (good, 5.08 h)	87.1° 05:25	6.43	31%	70.2°
2027-05-01 Sat	100	—	unknown	23:25–04:30 (good, 5.08 h)	87.1° 05:20	6.38	22%	74.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-04-02&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.