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<DIV dir=ltr align=left><SPAN class=011522817-06092006><FONT face=Arial
color=#0000ff size=2>I've done more research and the 90 part of NAD83/90 seems
to refer to the 1990 adjustment (as John said below). This is new to me as
I've never referred to NAD83 in another way. Does anyone know what
the latest adjustment is? and what ESRI's ArcGIS uses?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=011522817-06092006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=011522817-06092006><FONT face=Arial
color=#0000ff size=2>I'll have to do more homework on this one. Thanks for
your help.</FONT></SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> Sykes, John
[mailto:John.Sykes@dep.state.fl.us] <BR><B>Sent:</B> Wednesday, September 06,
2006 11:59 AM<BR><B>To:</B> Thomas, Jim<BR><B>Subject:</B> RE: shrug-l:
NAD83/90<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV dir=ltr align=left><SPAN class=438395015-06092006><FONT face=Tahoma
color=#0000ff>My understanding is that the NAD83 is the "standard" replacement
for NAD27.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=438395015-06092006><FONT face=Tahoma
color=#0000ff></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=438395015-06092006><FONT face=Tahoma
color=#0000ff>NAD83 HARN and NAD83/90HPGN are, essentially, the same.
Originally it was called the High Precision Geographical Network, but was
subsequently changed to High Accuracy Regional Network (or something like
that).</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=438395015-06092006><FONT face=Tahoma
color=#0000ff></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=438395015-06092006><FONT face=Tahoma
color=#0000ff>The difference between NAD83 and NAD27 is several meters (up to
around 100 meters in parts of Florida), but NAD83 to NAD83 HARN is usually in
the centimeter range (in most of Florida).</FONT></SPAN></DIV>
<DIV><FONT face=Tahoma color=#0000ff></FONT> </DIV>
<DIV><SPAN class=438395015-06092006><FONT face=Tahoma color=#0000ff>Note:
It is also my understanding that the NAD83/90 is the "standard" version of NAD83
and, therefore, is redundant. So usually you would see just NAD83 or NAD83
HARN, the "90" is assumed (not necessarily the case with HARN, which I believe
is set to a later epoch [2004????]). HPGN is no longer used. If
you want to confirm the epoch, look up a CORS station in the NGS datasheets, it
will give the epoch information as well as the drift information (Florida is
drifting northwest at about 1 cm/yr).</FONT></SPAN></DIV><!-- Converted from text/rtf format -->
<P><B><SPAN lang=en-us><FONT face="Brush Script MT" size=6>--
John</FONT></SPAN></B><SPAN lang=en-us></SPAN> </P>
<DIV> </DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> shrug-l-bounces@lists.dep.state.fl.us
[mailto:shrug-l-bounces@lists.dep.state.fl.us] <B>On Behalf Of </B>Thomas,
Jim<BR><B>Sent:</B> Wednesday, September 06, 2006 11:27 AM<BR><B>To:</B>
shrug-l@lists.dep.state.fl.us<BR><B>Subject:</B> shrug-l:
NAD83/90<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV><FONT face=Arial size=2><SPAN class=683431715-06092006>Can someone briefly
explain the difference among the following.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=683431715-06092006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN
class=683431715-06092006>NAD83</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=683431715-06092006>NAD83
HARN</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=683431715-06092006>NAD83/90
HPGN</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=683431715-06092006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=683431715-06092006>Is NAD83 HARN the
same as NAD83/90 HPGN?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=683431715-06092006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=683431715-06092006>I'm getting requests
to have coordinates reported in NAD83/90 and need to understand the
difference.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=683431715-06092006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=683431715-06092006>Thanks for you
help.</SPAN></FONT></DIV></BODY></HTML>