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: 02-27 (93), 02-28 (93), 03-01 (93), 03-02 (93), 03-03 (93) — by astronomy; check the weather when the night is within four days.

2027-02-16astronomy score per night — click a bar for that night2027-03-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-02-16 Tue	90	—	unknown	23:45–05:45 (good, 6.0 h)	50.2° 03:05	10.22	78%	93.1°
2027-02-17 Wed	85	—	unknown	01:25–05:40 (good, 4.25 h)	50.2° 03:00	10.18	87%	78.6°
2027-02-18 Thu	55	—	unknown	05:10–05:40 (good, 0.5 h)	50.2° 02:55	10.13	94%	63.9°
2027-02-19 Fri	37	—	unknown	23:35–05:40 (marginal, 6.08 h)	50.2° 02:55	10.09	98%	49.2°
2027-02-20 Sat	24	—	unknown	02:20–05:40 (marginal, 3.33 h)	50.2° 02:50	10.05	100%	34.7°
2027-02-21 Sun	21	—	unknown	02:50–05:35 (marginal, 2.75 h)	50.2° 02:45	10.01	99%	20.9°
2027-02-22 Mon	24	—	unknown	23:05–05:35 (marginal, 6.5 h)	50.2° 02:40	9.97	95%	9.8°
2027-02-23 Tue	32	—	unknown	22:40–05:35 (marginal, 6.92 h)	50.2° 02:35	9.92	89%	12.4°
2027-02-24 Wed	49	—	unknown	22:20–05:35 (marginal, 7.25 h)	50.2° 02:35	9.88	81%	24.0°
2027-02-25 Thu	84	—	unknown	22:40–02:00 (good, 3.33 h)	50.2° 02:30	9.84	72%	36.4°
2027-02-26 Fri	90	—	unknown	22:40–05:05 (good, 6.42 h)	50.2° 02:25	9.79	62%	48.7°
2027-02-27 Sat	93	—	unknown	22:35–05:30 (good, 6.92 h)	50.2° 02:20	9.75	53%	60.8°
2027-02-28 Sun	93	—	unknown	22:30–05:25 (good, 6.92 h)	50.2° 02:15	9.7	43%	72.7°
2027-03-01 Mon	93	—	unknown	22:25–05:25 (good, 7.0 h)	50.2° 02:15	9.66	34%	84.5°
2027-03-02 Tue	93	—	unknown	22:20–05:25 (good, 7.08 h)	50.2° 02:10	9.61	25%	96.2°
2027-03-03 Wed	93	—	unknown	22:20–05:20 (good, 7.0 h)	50.2° 02:05	9.57	18%	107.9°
2027-03-04 Thu	93	—	unknown	22:15–05:20 (good, 7.08 h)	50.2° 02:00	9.52	11%	119.6°
2027-03-05 Fri	93	—	unknown	22:10–05:20 (good, 7.17 h)	50.2° 02:00	9.47	6%	131.4°
2027-03-06 Sat	93	—	unknown	22:05–05:15 (good, 7.17 h)	50.2° 01:55	9.43	2%	143.3°
2027-03-07 Sun	93	—	unknown	22:05–05:15 (good, 7.17 h)	50.2° 01:50	9.38	0%	155.1°
2027-03-08 Mon	93	—	unknown	22:00–05:15 (good, 7.25 h)	50.2° 01:45	9.33	0%	166.2°
2027-03-09 Tue	93	—	unknown	21:55–05:10 (good, 7.25 h)	50.2° 01:40	9.28	3%	171.3°
2027-03-10 Wed	93	—	unknown	21:50–05:10 (good, 7.33 h)	50.2° 01:40	9.23	7%	162.9°
2027-03-11 Thu	93	—	unknown	21:50–05:10 (good, 7.33 h)	50.2° 01:35	9.19	13%	150.8°
2027-03-12 Fri	93	—	unknown	21:45–05:05 (good, 7.33 h)	50.2° 01:30	9.14	21%	137.8°
2027-03-13 Sat	93	—	unknown	21:40–05:05 (good, 7.42 h)	50.2° 01:25	9.09	31%	124.5°
2027-03-14 Sun	93	—	unknown	21:40–05:05 (good, 7.42 h)	50.2° 01:20	9.04	42%	110.9°
2027-03-15 Mon	91	—	unknown	21:45–05:00 (good, 7.25 h)	50.2° 01:20	8.99	53%	97.1°
2027-03-16 Tue	87	—	unknown	21:55–05:00 (good, 7.08 h)	50.2° 01:15	8.94	64%	83.1°
2027-03-17 Wed	83	—	unknown	23:45–05:00 (good, 5.25 h)	50.2° 01:10	8.89	75%	68.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-02-16&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.