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: 02-17 (93), 02-18 (93), 02-19 (93), 02-20 (93), 02-21 (93) — by astronomy; check the weather when the night is within four days.

2028-02-16astronomy score per night — click a bar for that night2028-03-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-02-16 Wed	90	—	unknown	23:20–05:45 (good, 6.42 h)	50.2° 03:05	10.23	54%	48.0°
2028-02-17 Thu	93	—	unknown	23:15–05:45 (good, 6.5 h)	50.2° 03:00	10.18	44%	60.7°
2028-02-18 Fri	93	—	unknown	23:10–05:40 (good, 6.5 h)	50.2° 03:00	10.14	34%	73.1°
2028-02-19 Sat	93	—	unknown	23:05–05:40 (good, 6.58 h)	50.2° 02:55	10.1	25%	85.3°
2028-02-20 Sun	93	—	unknown	23:05–05:40 (good, 6.58 h)	50.2° 02:50	10.06	17%	97.3°
2028-02-21 Mon	93	—	unknown	23:00–05:35 (good, 6.58 h)	50.2° 02:45	10.02	10%	109.1°
2028-02-22 Tue	93	—	unknown	22:55–05:35 (good, 6.67 h)	50.2° 02:40	9.98	6%	120.8°
2028-02-23 Wed	93	—	unknown	22:50–05:35 (good, 6.75 h)	50.2° 02:40	9.93	2%	132.4°
2028-02-24 Thu	93	—	unknown	22:45–05:35 (good, 6.83 h)	50.2° 02:35	9.89	0%	143.8°
2028-02-25 Fri	93	—	unknown	22:45–05:30 (good, 6.75 h)	50.2° 02:30	9.85	0%	155.0°
2028-02-26 Sat	93	—	unknown	22:40–05:30 (good, 6.83 h)	50.2° 02:25	9.8	2%	165.3°
2028-02-27 Sun	93	—	unknown	22:35–05:30 (good, 6.92 h)	50.2° 02:20	9.76	6%	170.6°
2028-02-28 Mon	93	—	unknown	22:30–05:25 (good, 6.92 h)	50.2° 02:20	9.71	11%	164.3°
2028-02-29 Tue	93	—	unknown	22:25–05:25 (good, 7.0 h)	50.2° 02:15	9.67	18%	153.5°
2028-03-01 Wed	93	—	unknown	22:25–05:25 (good, 7.0 h)	50.2° 02:10	9.62	26%	141.8°
2028-03-02 Thu	93	—	unknown	22:25–05:25 (good, 7.0 h)	50.2° 02:05	9.58	35%	129.5°
2028-03-03 Fri	93	—	unknown	22:20–05:20 (good, 7.0 h)	50.2° 02:00	9.53	45%	116.8°
2028-03-04 Sat	93	—	unknown	22:25–05:20 (good, 6.92 h)	50.2° 02:00	9.48	56%	103.7°
2028-03-05 Sun	90	—	unknown	22:35–05:20 (good, 6.75 h)	50.2° 01:55	9.44	67%	90.2°
2028-03-06 Mon	85	—	unknown	23:50–05:15 (good, 5.42 h)	50.2° 01:50	9.39	77%	76.2°
2028-03-07 Tue	81	—	unknown	02:35–05:15 (good, 2.67 h)	50.2° 01:45	9.34	86%	61.8°
2028-03-08 Wed	45	—	unknown	22:15–05:15 (marginal, 7.0 h)	50.2° 01:45	9.29	93%	47.2°
2028-03-09 Thu	28	—	unknown	01:00–05:10 (marginal, 4.17 h)	50.2° 01:40	9.25	98%	32.6°
2028-03-10 Fri	24	—	unknown	01:45–05:10 (marginal, 3.42 h)	50.2° 01:35	9.2	100%	18.6°
2028-03-11 Sat	25	—	unknown	21:55–05:05 (marginal, 7.17 h)	50.2° 01:30	9.15	99%	9.5°
2028-03-12 Sun	33	—	unknown	21:30–05:05 (marginal, 7.58 h)	50.2° 01:25	9.1	95%	16.7°
2028-03-13 Mon	71	—	unknown	21:35–22:00 (good, 0.42 h)	50.2° 01:25	9.05	88%	29.8°
2028-03-14 Tue	87	—	unknown	21:30–01:10 (good, 3.67 h)	50.2° 01:20	9.0	80%	43.2°
2028-03-15 Wed	92	—	unknown	21:30–03:50 (good, 6.33 h)	50.2° 01:15	8.95	70%	56.5°
2028-03-16 Thu	93	—	unknown	21:25–04:40 (good, 7.25 h)	50.2° 01:10	8.9	60%	69.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-02-16&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.