Purbach is a large lunar

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 crater

Impact crater

In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

 located in the rugged southern highlands of the Moon

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

. The distorted crater Regiomontanus

Regiomontanus (crater)

Regiomontanus is an ancient lunar impact crater located in the southern highlands region to the southeast of Mare Nubium. It is joined at the chaotic northern rim by the crater Purbach, and to the south-southeast is Walther....

 is attached to the southern rim. To the northwest is Thebit

Thebit (crater)

Thebit is a lunar impact crater located on the southeast shore of Mare Nubium. To the north-northwest is the crater Arzachel, and Purbach lies to the south-southwest. To the southwest is the flooded remnants of Thebit P, which is actually larger in diameter than Thebit itself.The rim of Thebit is...

 and just to the northeast lies La Caille

La Caille (crater)

La Caille is a lunar crater located in the rugged south-central highlands of the Moon. It is located to the northeast of the crater Purbach. Nearly attached to the southeast rim are the remains of Blanchinus, and the two are separated by a rugged stretch of terrain...

.

The outer wall of Purbach is heavily worn, with the most intact section being along the east and northeast sides. The shared rim between Purbach and Regiomontanus is incised and rugged. The wall is distorted along the western edge, giving the appearance of a double rim, with the second rim distended towards the west. The northern wall is almost completely destroyed, and somewhat irregular Purbach G lies across the northwest rim.

The crater floor is relatively smooth in the eastern half, with a low series of ridges and a partial ghost crater

Palimpsest

A palimpsest is a manuscript page from a scroll or book from which the text has been scraped off and which can be used again. The word "palimpsest" comes through Latin palimpsēstus from Ancient Greek παλίμψηστος originally compounded from πάλιν and ψάω literally meaning “scraped...

outline just to the west of the crater mid-point. If the crater possessed a central peak, it has either been removed or forms part of the ridges to the west.

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater mid-point that is closest to Purbach.

Purbach	Latitude	Longitude	Diameter
A	26.1° S	1.9° W	8 km
B	26.9° S	4.2° W	16 km
C	27.7° S	4.6° W	18 km
D	22.8° S	1.6° W	12 km
E	21.7° S	0.7° W	23 km
F	24.6° S	0.0° W	9 km
G	23.9° S	2.8° W	27 km
H	25.5° S	5.6° W	29 km
J	27.5° S	3.9° W	12 km
K	25.2° S	4.6° W	8 km
L	25.1° S	5.0° W	17 km
M	24.8° S	4.4° W	17 km
N	26.2° S	5.4° W	7 km
O	24.7° S	3.8° W	5 km
P	26.4° S	3.7° W	5 km
Q	25.9° S	0.0° W	4 km
R	26.5° S	3.2° W	4 km
S	27.3° S	2.3° W	9 km
T	24.6° S	0.9° W	5 km
U	27.0° S	2.0° W	15 km
V	26.7° S	0.3° W	6 km
W	25.5° S	2.3° W	20 km
X	25.4° S	1.1° W	4 km
Y	25.8° S	6.8° W	16 km