<s>
The	O
Wide	B-Algorithm
Field	I-Algorithm
and	I-Algorithm
Planetary	I-Algorithm
Camera	I-Algorithm
2	I-Algorithm
(	O
WFPC2	B-Algorithm
)	O
is	O
a	O
camera	O
formerly	O
installed	O
on	O
the	O
Hubble	O
Space	O
Telescope	O
.	O
</s>
<s>
It	O
was	O
installed	O
by	O
servicing	O
mission	O
1	O
(	O
STS-61	O
)	O
in	O
1993	O
,	O
replacing	O
the	O
telescope	O
's	O
original	O
Wide	B-Algorithm
Field	I-Algorithm
and	I-Algorithm
Planetary	I-Algorithm
Camera	I-Algorithm
(	O
WF/PC	B-Algorithm
)	O
.	O
</s>
<s>
WFPC2	B-Algorithm
was	O
used	O
to	O
image	O
the	O
Hubble	O
Deep	O
Field	O
in	O
1995	O
,	O
the	O
Engraved	O
Hourglass	O
Nebula	O
and	O
Egg	O
Nebula	O
in	O
1996	O
,	O
and	O
the	O
Hubble	O
Deep	O
Field	O
South	O
in	O
1998	O
.	O
</s>
<s>
During	O
STS-125	O
,	O
WFPC2	B-Algorithm
was	O
removed	O
and	O
replaced	O
with	O
the	O
Wide	B-Algorithm
Field	I-Algorithm
Camera	I-Algorithm
3	I-Algorithm
as	O
part	O
of	O
the	O
mission	O
's	O
first	O
spacewalk	O
on	O
May	O
14	O
,	O
2009	O
.	O
</s>
<s>
WFPC2	B-Algorithm
was	O
built	O
by	O
NASA	O
's	O
Jet	O
Propulsion	O
Laboratory	O
,	O
which	O
also	O
built	O
the	O
predecessor	O
WFPC	B-Algorithm
camera	O
launched	O
with	O
Hubble	O
in	O
1990	O
.	O
</s>
<s>
WFPC2	B-Algorithm
contains	O
internal	O
corrective	O
optics	O
to	O
fix	O
the	O
spherical	O
aberration	O
in	O
the	O
Hubble	O
telescope	O
's	O
primary	O
mirror	O
.	O
</s>
<s>
The	O
charge-coupled	B-Algorithm
devices	I-Algorithm
(	O
CCDs	O
)	O
in	O
the	O
WFPC2	B-Algorithm
(	O
designed	O
at	O
JPL	O
and	O
manufactured	O
by	O
Loral	O
)	O
detected	O
electromagnetic	O
radiation	O
in	O
a	O
range	O
from	O
120	O
nm	O
to	O
1000nm	O
.	O
</s>
<s>
This	O
included	O
the	O
380nm	O
to	O
780nm	O
of	O
the	O
visible	O
spectrum	O
,	O
all	O
of	O
the	O
near	O
ultraviolet	B-Application
(	O
and	O
a	O
small	O
part	O
of	O
the	O
extreme	O
ultraviolet	B-Application
band	O
)	O
and	O
most	O
of	O
the	O
near-infrared	O
band	O
.	O
</s>
<s>
WFPC2	B-Algorithm
featured	O
four	O
identical	O
CCD	B-Algorithm
detectors	O
,	O
each	O
800x800	O
pixels	B-Algorithm
.	O
</s>
<s>
Adjacent	O
to	O
them	O
is	O
the	O
Planetary	O
Camera	O
(	O
PC	O
)	O
,	O
a	O
fourth	O
CCD	B-Algorithm
with	O
different	O
(	O
narrower-focused	O
)	O
optics	O
.	O
</s>
<s>
WFC	O
and	O
PC	O
images	O
are	O
typically	O
combined	O
,	O
producing	O
the	O
WFPC2	B-Algorithm
's	O
characteristic	O
stairstep	O
image	O
.	O
</s>
<s>
To	O
allow	O
scientists	O
to	O
view	O
specific	O
parts	O
of	O
the	O
electromagnetic	O
spectrum	O
the	O
WFPC2	B-Algorithm
featured	O
a	O
rotating	O
wheel	O
which	O
moves	O
different	O
optical	O
filters	O
into	O
the	O
lightpath	O
(	O
between	O
the	O
WFPC2	B-Algorithm
's	O
aperture	B-General_Concept
and	O
the	O
CCD	B-Algorithm
detectors	O
)	O
.	O
</s>
<s>
As	O
predicted	O
,	O
over	O
the	O
course	O
of	O
its	O
mission	O
the	O
WFPC2	B-Algorithm
experienced	O
degradation	O
of	O
the	O
CCDs	O
,	O
resulting	O
in	O
defective	O
(	O
"	O
hot	O
"	O
)	O
pixels	B-Algorithm
.	O
</s>
<s>
The	O
telescope	O
's	O
operators	O
performed	O
monthly	O
calibration	O
tests	O
to	O
catalog	O
these	O
;	O
with	O
the	O
WFPC	B-Algorithm
's	O
aperture	B-General_Concept
closed	O
a	O
number	O
of	O
long	O
exposures	O
are	O
taken	O
,	O
and	O
pixels	B-Algorithm
which	O
differ	O
significantly	O
from	O
near	O
black	O
are	O
flagged	O
.	O
</s>
<s>
To	O
avoid	O
false	O
positives	O
caused	O
by	O
cosmic	O
rays	O
tripping	O
a	O
given	O
pixel	B-Algorithm
,	O
the	O
output	O
of	O
different	O
calibration	O
shots	O
is	O
compared	O
.	O
</s>
<s>
Pixels	B-Algorithm
which	O
are	O
consistently	O
"	O
hot	O
"	O
are	O
recorded	O
,	O
and	O
astronomers	O
who	O
analyse	O
raw	O
WFPC2	B-Algorithm
images	O
receive	O
a	O
list	O
of	O
these	O
pixels	B-Algorithm
.	O
</s>
<s>
Typically	O
,	O
astronomers	O
adjust	O
their	O
photo-processing	O
software	O
to	O
ignore	O
these	O
bad	O
pixels	B-Algorithm
.	O
</s>
<s>
WFPC2	B-Algorithm
was	O
largely	O
superseded	O
for	O
broad-band	O
imaging	O
by	O
the	O
Advanced	B-Algorithm
Camera	I-Algorithm
for	I-Algorithm
Surveys	I-Algorithm
,	O
installed	O
during	O
servicing	O
mission	O
3B	O
in	O
2002	O
.	O
</s>
<s>
However	O
,	O
the	O
early	O
2007	O
failure	O
of	O
ACS	O
resulted	O
in	O
WFPC2	B-Algorithm
returning	O
to	O
its	O
role	O
as	O
Hubble	O
's	O
primary	O
visible	O
light	O
camera	O
.	O
</s>
<s>
WFPC2	B-Algorithm
was	O
removed	O
from	O
HST	O
during	O
Servicing	O
Mission	O
4	O
in	O
May	O
2009	O
,	O
for	O
return	O
to	O
Earth	O
and	O
eventual	O
museum	O
display	O
.	O
</s>
<s>
It	O
was	O
replaced	O
by	O
Wide	B-Algorithm
Field	I-Algorithm
Camera	I-Algorithm
3	I-Algorithm
,	O
which	O
features	O
two	O
UV/visible	O
detecting	O
CCDs	O
,	O
each	O
2048x4096	O
pixels	B-Algorithm
,	O
and	O
a	O
separate	O
IR	O
CCD	B-Algorithm
of	O
1024	O
x	O
1024	O
,	O
capable	O
of	O
receiving	O
infrared	O
radiation	O
up	O
to	O
1700nm	O
.	O
</s>
