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 3C 273: 04-01 (93), 04-02 (93), 04-03 (93), 04-04 (93), 04-05 (93) — by astronomy; check the weather when the night is within four days.

2040-03-20astronomy score per night — click a bar for that night2040-04-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-03-20 Tue	91	—	unknown	21:25–04:50 (good, 7.42 h)	50.1° 00:55	8.69	52%	92.7°
2040-03-21 Wed	86	—	unknown	21:35–04:45 (good, 7.17 h)	50.1° 00:50	8.64	61%	80.9°
2040-03-22 Thu	81	—	unknown	23:05–04:40 (good, 5.58 h)	50.1° 00:50	8.59	70%	69.0°
2040-03-23 Fri	62	—	unknown	02:05–03:50 (good, 1.75 h)	50.1° 00:45	8.53	78%	57.0°
2040-03-24 Sat	46	—	unknown	21:10–05:45 (marginal, 7.58 h)	50.1° 00:40	8.48	86%	44.8°
2040-03-25 Sun	29	—	unknown	00:35–05:40 (marginal, 5.08 h)	50.1° 01:35	8.43	92%	32.4°
2040-03-26 Mon	23	—	unknown	02:20–05:25 (marginal, 3.08 h)	50.1° 01:30	8.37	97%	19.6°
2040-03-27 Tue	20	—	unknown	03:15–05:10 (marginal, 1.92 h)	50.1° 01:30	8.32	99%	6.6°
2040-03-28 Wed	22	—	unknown	21:45–00:35 (marginal, 2.83 h)	50.1° 01:25	8.27	100%	6.7°
2040-03-29 Thu	30	—	unknown	21:25–04:50 (marginal, 7.42 h)	50.1° 01:20	8.21	98%	20.3°
2040-03-30 Fri	74	—	unknown	21:30–22:05 (good, 0.58 h)	50.1° 01:15	8.16	94%	34.1°
2040-03-31 Sat	88	—	unknown	21:25–00:35 (good, 3.17 h)	50.1° 01:15	8.1	87%	48.1°
2040-04-01 Sun	93	—	unknown	21:25–03:30 (good, 6.08 h)	50.1° 01:10	8.05	79%	62.2°
2040-04-02 Mon	93	—	unknown	21:25–04:35 (good, 7.17 h)	50.1° 01:05	7.99	68%	76.3°
2040-04-03 Tue	93	—	unknown	21:30–04:40 (good, 7.17 h)	50.1° 01:00	7.94	57%	90.5°
2040-04-04 Wed	93	—	unknown	21:30–04:40 (good, 7.17 h)	50.1° 00:55	7.88	46%	104.6°
2040-04-05 Thu	93	—	unknown	21:30–04:40 (good, 7.17 h)	50.1° 00:55	7.83	35%	118.7°
2040-04-06 Fri	93	—	unknown	21:30–04:40 (good, 7.17 h)	50.1° 00:50	7.77	24%	132.8°
2040-04-07 Sat	93	—	unknown	21:35–04:35 (good, 7.0 h)	50.1° 00:45	7.72	16%	146.8°
2040-04-08 Sun	93	—	unknown	21:35–04:35 (good, 7.0 h)	50.1° 00:40	7.66	8%	160.6°
2040-04-09 Mon	93	—	unknown	21:35–04:30 (good, 6.92 h)	50.1° 00:35	7.6	3%	174.3°
2040-04-10 Tue	93	—	unknown	21:40–04:25 (good, 6.75 h)	50.1° 00:35	7.55	1%	172.2°
2040-04-11 Wed	93	—	unknown	21:40–04:20 (good, 6.67 h)	50.1° 00:30	7.49	0%	159.0°
2040-04-12 Thu	93	—	unknown	21:40–04:15 (good, 6.58 h)	50.1° 00:25	7.43	2%	146.1°
2040-04-13 Fri	93	—	unknown	21:40–04:15 (good, 6.58 h)	50.1° 00:20	7.37	6%	133.4°
2040-04-14 Sat	93	—	unknown	21:45–04:10 (good, 6.42 h)	50.1° 00:20	7.32	11%	121.0°
2040-04-15 Sun	93	—	unknown	21:45–04:05 (good, 6.33 h)	50.1° 00:15	7.26	18%	108.8°
2040-04-16 Mon	92	—	unknown	21:45–04:00 (good, 6.25 h)	50.1° 00:10	7.2	26%	96.8°
2040-04-17 Tue	88	—	unknown	21:50–04:00 (good, 6.17 h)	50.1° 00:05	7.14	35%	84.9°
2040-04-18 Wed	83	—	unknown	21:50–03:55 (good, 6.08 h)	50.1° 00:00	7.08	44%	73.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-03-20&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.