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: 08-19 (71), 08-18 (70), 08-20 (68), 08-17 (67), 08-16 (66) — by astronomy; check the weather when the night is within four days.

2040-07-27astronomy score per night — click a bar for that night2040-08-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-07-27 Fri	9	—	unknown	03:20–04:20 (marginal, 1.0 h)	72.5° 08:45	5.61	80%	61.4°
2040-07-28 Sat	9	—	unknown	03:20–04:20 (marginal, 1.0 h)	72.5° 08:40	5.66	70%	47.6°
2040-07-29 Sun	10	—	unknown	03:10–04:20 (marginal, 1.17 h)	72.5° 08:35	5.72	60%	34.4°
2040-07-30 Mon	13	—	unknown	03:00–04:25 (marginal, 1.42 h)	72.5° 08:30	5.77	49%	21.6°
2040-07-31 Tue	17	—	unknown	03:45–04:25 (good, 0.67 h)	72.5° 08:30	5.83	39%	9.6°
2040-08-01 Wed	22	—	unknown	03:35–04:25 (good, 0.83 h)	72.5° 08:25	5.88	30%	5.6°
2040-08-02 Thu	27	—	unknown	03:25–04:30 (good, 1.08 h)	72.5° 08:20	5.94	22%	16.3°
2040-08-03 Fri	31	—	unknown	03:15–04:30 (good, 1.25 h)	72.5° 08:15	5.99	14%	28.0°
2040-08-04 Sat	36	—	unknown	03:05–04:30 (good, 1.42 h)	72.5° 08:10	6.05	8%	39.7°
2040-08-05 Sun	40	—	unknown	03:05–04:35 (good, 1.5 h)	72.5° 08:10	6.1	4%	51.4°
2040-08-06 Mon	43	—	unknown	03:00–04:35 (good, 1.58 h)	72.5° 08:05	6.16	1%	63.2°
2040-08-07 Tue	44	—	unknown	02:55–04:35 (good, 1.67 h)	72.5° 08:00	6.22	0%	75.1°
2040-08-08 Wed	47	—	unknown	02:50–04:40 (good, 1.83 h)	72.5° 07:55	6.28	1%	87.0°
2040-08-09 Thu	49	—	unknown	02:45–04:40 (good, 1.92 h)	72.5° 07:55	6.33	4%	99.0°
2040-08-10 Fri	51	—	unknown	02:45–04:40 (good, 1.92 h)	72.5° 07:50	6.39	8%	111.2°
2040-08-11 Sat	53	—	unknown	02:40–04:40 (good, 2.0 h)	72.5° 07:45	6.45	14%	123.5°
2040-08-12 Sun	56	—	unknown	02:35–04:45 (good, 2.17 h)	72.5° 07:40	6.5	22%	136.1°
2040-08-13 Mon	58	—	unknown	02:30–04:45 (good, 2.25 h)	72.5° 07:35	6.56	31%	148.8°
2040-08-14 Tue	60	—	unknown	02:25–04:45 (good, 2.33 h)	72.5° 07:35	6.62	41%	161.7°
2040-08-15 Wed	63	—	unknown	02:25–04:50 (good, 2.42 h)	72.5° 07:30	6.68	52%	174.0°
2040-08-16 Thu	66	—	unknown	02:20–04:50 (good, 2.5 h)	72.5° 07:25	6.73	63%	169.8°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-07-27&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.