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 Seven Sisters: 09-03 (100), 09-04 (100), 09-05 (100), 09-06 (100), 09-07 (100) — by astronomy; check the weather when the night is within four days.

2040-08-17astronomy score per night — click a bar for that night2040-09-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-08-17 Fri	67	—	unknown	02:15–04:50 (good, 2.58 h)	72.5° 07:20	6.79	73%	156.1°
2040-08-18 Sat	70	—	unknown	02:15–04:55 (good, 2.67 h)	72.5° 07:15	6.85	83%	141.7°
2040-08-19 Sun	71	—	unknown	02:15–04:55 (good, 2.67 h)	72.5° 07:15	6.91	91%	126.9°
2040-08-20 Mon	68	—	unknown	02:15–04:55 (good, 2.67 h)	72.5° 07:10	6.96	97%	112.0°
2040-08-21 Tue	49	—	unknown	02:25–04:55 (good, 2.5 h)	72.5° 07:05	7.02	100%	97.0°
2040-08-22 Wed	39	—	unknown	03:35–05:00 (good, 1.42 h)	72.5° 07:00	7.08	99%	82.0°
2040-08-23 Thu	29	—	unknown	01:40–05:00 (marginal, 3.33 h)	72.5° 07:00	7.14	96%	67.4°
2040-08-24 Fri	22	—	unknown	01:45–05:00 (marginal, 3.25 h)	72.5° 06:55	7.19	91%	53.1°
2040-08-25 Sat	18	—	unknown	01:45–05:05 (marginal, 3.33 h)	72.5° 06:50	7.25	84%	39.2°
2040-08-26 Sun	19	—	unknown	01:35–05:05 (marginal, 3.5 h)	72.5° 06:45	7.31	75%	25.9°
2040-08-27 Mon	26	—	unknown	01:20–05:05 (marginal, 3.75 h)	72.5° 06:40	7.36	65%	13.2°
2040-08-28 Tue	36	—	unknown	01:05–05:05 (marginal, 4.0 h)	72.5° 06:40	7.42	55%	4.0°
2040-08-29 Wed	48	—	unknown	01:55–05:10 (good, 3.25 h)	72.5° 06:35	7.48	46%	12.9°
2040-08-30 Thu	60	—	unknown	01:40–05:10 (good, 3.5 h)	72.5° 06:30	7.53	36%	24.6°
2040-08-31 Fri	74	—	unknown	01:20–05:10 (good, 3.83 h)	72.5° 06:25	7.59	27%	36.4°
2040-09-01 Sat	89	—	unknown	01:15–05:15 (good, 4.0 h)	72.5° 06:20	7.65	19%	48.2°
2040-09-02 Sun	96	—	unknown	01:10–05:15 (good, 4.08 h)	72.5° 06:20	7.7	12%	60.0°
2040-09-03 Mon	100	—	unknown	01:10–05:15 (good, 4.08 h)	72.5° 06:15	7.76	7%	71.8°
2040-09-04 Tue	100	—	unknown	01:05–05:15 (good, 4.17 h)	72.5° 06:10	7.81	3%	83.8°
2040-09-05 Wed	100	—	unknown	01:00–05:20 (good, 4.33 h)	72.5° 06:05	7.87	1%	95.8°
2040-09-06 Thu	100	—	unknown	00:55–05:20 (good, 4.42 h)	72.5° 06:05	7.92	0%	108.1°
2040-09-07 Fri	100	—	unknown	00:55–05:20 (good, 4.42 h)	72.5° 06:00	7.98	2%	120.5°
2040-09-08 Sat	100	—	unknown	00:50–05:20 (good, 4.5 h)	72.5° 05:55	8.03	5%	133.1°
2040-09-09 Sun	100	—	unknown	00:45–05:25 (good, 4.67 h)	72.5° 05:50	8.08	11%	145.9°
2040-09-10 Mon	100	—	unknown	00:40–05:25 (good, 4.75 h)	72.5° 05:45	8.14	18%	158.8°
2040-09-11 Tue	100	—	unknown	00:35–05:25 (good, 4.83 h)	72.5° 05:45	8.19	27%	171.5°
2040-09-12 Wed	100	—	unknown	00:35–05:25 (good, 4.83 h)	72.5° 05:40	8.25	37%	173.0°
2040-09-13 Thu	100	—	unknown	00:30–05:30 (good, 5.0 h)	72.5° 05:35	8.3	48%	160.0°
2040-09-14 Fri	100	—	unknown	00:25–05:30 (good, 5.08 h)	72.5° 05:30	8.35	60%	146.1°
2040-09-15 Sat	100	—	unknown	00:25–05:30 (good, 5.08 h)	72.5° 05:25	8.4	70%	131.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-08-17&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.