The back contains 6 scales of the following types:
| Type (click to view scale details) |
Range & Units | Numbered | Geometry | Location |
|---|---|---|---|---|
| Degree | 0 - 90, Degrees | Every 10 degrees | None | The entire outer circle on the back of an astrolabe. |
| Zodiacal signs | 0 - 30, Zodiacal divisions, equal or unequal | Every 10 | Circular, concentric | Circular scale immediately inside the outer scale - refers to the full circle |
| Lunar Mansions | Lunar mansion | Each one | Circular, concentric | Circular scale second in from the outer scale - refers to the full circle. |
| Calendar | First day of month - Last day of month, Days of year | Every 10 and end of month days | Circular, eccentric | Circular scale third in from the outer scale - refers to the full circle. |
| Unequal hours | 1 - 6, 1/12 of daylight | Not numbered hours | Arc | The upper two quadrants of the back of the instrument |
| Shadow square | 1 - 12, Fingers | Every 3 fingers | Box | The lower two quadrants of the back of the instrument |
| Transcription | Translation | Notes | Type |
|---|---|---|---|
| 1490 | This date is engraved in the center of the unequal-hour scale | Date | |
| h T b | Hans Bamman of Thüringen | The central T is enclosed in a triangle. Together, the three initials are typical of Hans Bamman | Maker's signature |