Corona Satellite Calibration Targets
(Site last updated 3-25-2019)

From 1966 to 1968 The Army Corp of Engineers poured concrete "Maltese" crosses
in the desert in, and around, the town of Casa Grande, AZ. This was done so that the
Corona spy satellite cameras (in operation since 1959) could be calibrated from their orbit
around the Earth. In 1972 the Corona project was discontinued. In the mid-to-late
1990's the Corona Project was declassified. There were originally 272 of these concrete
target crosses laid out in a grid one mile apart from each other that was 17 miles square.
The western border and the southern border of this grid only had a target located at
every other mile so that when viewing the images that were taken by the Corona cameras
the orientation was known. The crosses themselves were about 60 feet across. The
concrete was poured in at least five segments - the four legs of the Maltese-style cross, and
the center cylinder which had a brass/bronze marker designating which target it was. A few
of the targets that are located on a mountain range were made primarily using rocks from the
surrounding area with only a border of concrete to outline the cross. This was presumably
done because it was difficult to haul that much concrete and supplies to these areas.

Owners of the land that the crosses were located on were given the option of having
them removed. In addition, the town was growing and areas were being cleared for new
developments. Still, it is believed that there are more than 150 targets currently in existence.

The table below will eventually have links to photos of all of the targets that I have personally
seen and photographed, along with the date that I confirmed it was present, and the year that
it was originally placed! If there is no date (and/or if the link is not active) I have not been to
that location yet, or it has already been confirmed that it does NOT exist. If there is an asterisk
next to the target designation, see the appropriate note below the table.

Current quantity of targets that I have photographed: 115

Eventually all of the target locations in the table below will have active links to images and/or information.
W43
5-27-18
1966
X43
5-27-18
1967
Y43
Z43*
5-27-18
196?
AA43
AB43
AC43
Missing
AD43
Missing
AE43
Missing
AF43
Missing
AG43
Missing
AH43
AJ43
AK43
AL43
AM43
5-22-18
1968
AN43

X44 Y44
5-27-18
1967
Z44*
5-27-18
196?
AA44 AB44 AC44
Missing
AD44
Missing
AE44
Missing
AF44
Missing
AG44
Missing
AH44 AJ44 AK44 AL44 AM44 AN44
W45 X45 Y45 Z45 AA45 AB45 AC45
Missing
AD45
Missing
AE45
Missing
AF45
Missing
AG45
Missing
AH45 AJ45 AK45
5-22-18
1967
AL45 AM45 AN45
6-8-18
196?

X46 Y46
5-27-18
1966
Z46
5-27-18
1966
AA46
5-27-18
1967
AB46 AC46 AD46 AE46
Missing
AF46 AG46 AH46 AJ46
5-22-18
1967
AK46
5-22-18
1967
AL46 AM46*
5-22-18
196?
AN46
W47
5-27-18
1966
X47
5-27-18
1967
Y47*
5-27-18
196?
Z47
5-27-18
1966
AA47
5-27-18
1966
AB47 AC47
5-14-18
1968
AD47*
5-28-18
1968
AE47
Missing
AF47 AG47*
5-31-18
196?
AH47 AJ47 AK47 AL47 AM47 AN47

X48
5-27-18
1967
Y48
5-27-18
1966
Z48
5-27-18
1966
AA48
5-20-18
1966
AB48*
5-?-18
1967
AC-48*
5-14-18
1967
AD48
5-14-18
1966
AE48
5-13-18
1966
AF48
5-15-18
1966
AG-48*
5-31-18
1966
AH48
5-21-18
1966
AJ48
5-21-18
1967
AK48 AL48 AM48
6-8-18
1967
AN48
W49
5-27-18
1966
X49
5-27-18
1966
Y49
5-28-18
1966
Z49
5-27-18
1966
AA49
5-20-18
1966
AB49
5-20-18
1966
AC49 AD49
5-13-18
1966
AE49
5-10-18
1966
AF49
5-19-18
1966
AG49 AH49
5-21-18
1966
AJ49(2)
5-13-18
1967
AK49 AL49 AM49 AN49

X50
6-17-18
1966
Y50
6-17-18
1966
Z50
7-1-18
1966
AA50
6-10-18
1966
AB50
6-10-18
1966
AC50
5-20-18
1966
AD50
5-13-18
1966
AE50 AF50 AG50*
5-20-18
1966
AH50*
5-20-18
196?
AJ50 AK50 AL50 AM50
6-8-18
1967
AN50
W51
6-17-18
1966
X51 Y51 Z51
6-10-18
1966
AA51 AB51
7-1-18
1966?
AC51
5-26-18
1966
AD51
5-20-18
1966
AE51 AF51 AG51 AH51 AJ51 AK51
6-3-18
1966
AL51 AM51 AN51
6-8-18
1966

X52 Y52 Z52
6-10-18
1966
AA52
6-10-18
1966
AB52 AC52
5-28-18
1966
AD52
7-29-18
1966
AE.52*
3-24-19
1966
AF52 AG52
5-20-18
1968
AH52 AJ52 AK52 AL52 AM52 AN52
6-8-18
1966
W53
X53 Y53 Z53
6-10-18
1966
AA53
6-10-18
1966
AB53
8-19-18
1966
AC53
7-29-18
1966
AD53
7-29-18
1966
AE53
7-29-18
1968
AF53 AG53
5-20-18
1966
AH53
5-20-18
1966
AJ53
5-20-18
1966
AK53 AL53 AM53 AN53

X54 Y54 Z54 AA54 AB54 AC54
11-11-18
1966
AD54 AE54
6-24-18
1966
AF54
7-?-18
1966
AG54 AH54 AJ54 AK54*
5-20-18
1966
AL54
AM54 AN54
W55
X55 Y55 Z55 AA55 AB55
AC55 AD55 AE55
6-24-18
1966
AF55
7-8-18
1966
AG55
7-8-18
1966
AH55 AJ55*
5-20-18
1966
AK55*
5-20-18
196?
AL55 AM55 AN55

X56
9-2-18
1966
Y56 Z.56*
8-19-18
1966

AB56
11-11-18
1966
AC56 AD56
6-3-18
1966
AE56 AF56
7-8-18
1966
AG56 AH56 AJ56
5-20-18
1966
AK56*
5-20-18
1968
AL56 AM56
6-2?-18
1966
AN56
W57
X57 Y57
9-2-18
1966
Z57
8-19-18
1966
AA57 AB57 AC57 AD57
6-3-18
1966
AE57 AF57 AG57 AH57
6-3-18
1966
AJ57
5-20-18
1966
AK57
6-24-18
1966
AL57 AM57 AN57

X58 Y58
9-16-18
1966
Z58
9-16-18
1966
AA58 AB58 AC58 AD58
6-3-18
1966
AE58
6-3-18
1966
AF58
6-3-18
1966
AG58
6-3-18
1966
AH58 AJ58 AK58 AL58
6-24-18
1966
AM58 AN58
W59

Y59
AA59
AC59
AE59
6-3-18
1966

AG59
6-3-18
1966

AJ59
AL59
6-24-18
1966

AN59

An empty table cell with a grey background means that no marker was ever placed at that location.


*Notes:
AK56 marker has been cut off. The concrete is cracked, but mostly all there.
AG50 marker has been severly damaged. (It looks like it has been shot with a shotgun).
AD47 marker station designation was re-stamped at some point.
AC48 designation is actually stamped "AC-48". Possibly only 1 of 2 known dashes used between the letters and numbers (also AG-48).
AE52 designation is actually stamped "AE.52" with a period in between AE and 52. Also, Z.56 is like this as well!
AJ49 2 is the only designation to have a number (2) after the normal two letter, two number format.
AF48 and AG48 each have two markers (one in the center and one on a leg of the cross)!
AB48 marker is completely missing.
AJ55 marker missing or buried deeply.
AK55 is in a private yard. Not easily accessible.
AK54 marker missing or buried deeply.
AM46 is missing completely. No remnants.
AG47 is missing completely or buried very deeply. Now under new power lines.
Z43 is missing completely or buried very deeply.
Z44 is completely missing.
Y47 marker missing. Concrete intact.
AH50 is completly missing or buried very deeply.