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<p>I gather you're still looking for suggestions. The answer
depends on how desperate you are.</p>
<p>If I was desperate, I'd consider reverse-engineering the
CALC(9/11) readers for the EPH files which effectively contain the
file format in detail. Then (since I rarely write fortran these
days) I'd rewrite the reader in C and add a writer (also in C) and
then verify that I could product bit-identical copies of the
files. This tool would need to accept the various DEXXX files you
want to work with.</p>
<p>Theoretically, most of the file is data organized by object in
time, so you can produce what you want by doing some sort of
concatenate or merge (in the overlap). It gets more tricky if the
epochs change (but I'm guessing it's all still ICRF).</p>
<p>Another random thought is that NAIF spice
(<a class="moz-txt-link-freetext" href="https://naif.jpl.nasa.gov/naif/">https://naif.jpl.nasa.gov/naif/</a>) needs to do the same sort of
thing. (SPICE is a general toolkit for working with geometry in
space missions.) Data is encoded in things called kernels and the
SPICE toolkit can read a variety of kernels to do whatever
calculations the user requires. There are such kernels for DEXXX
at <a
href="https://naif.jpl.nasa.gov/pub/naif/generic_kernels/spk/planets"
class="moz-txt-link-freetext">https://naif.jpl.nasa.gov/pub/naif/generic_kernels/spk/planets</a>
and there are toolkits in C, Fortran and other languages.<br>
</p>
<p>There is a small discussion of SPICE and DE here: <a
href="https://astronomy.stackexchange.com/questions/54110/what-is-the-difference-between-spice-kernels-and-jpl-development-ephemerides-is"
class="moz-txt-link-freetext">https://astronomy.stackexchange.com/questions/54110/what-is-the-difference-between-spice-kernels-and-jpl-development-ephemerides-is</a><br>
</p>
<div class="moz-cite-prefix">On 1/23/25 10:01, Jan Wagner via
Difx-users wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CABEA3tpDCxxkAtxxozoBh5z-smx0=_pusX1nxnCXGpbcPVdh8g@mail.gmail.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<div dir="ltr">Hi David, Walter, all,<br>
<br>
that was a great amount of useful info from everyone! Many
thanks!<br>
<br>
I tried out Walter's idea, but alas, not successful. Edited
CALC5Server.c and increased the hard-coded limit of
solar_target[5000] and associated for() loop to something bigger
(I used 15000), modified one debug printout to ascertain the
warning comes indeed from the edited copy of CalcServer, then
recompiled and restarted CalcServer. The error is the same as
before,<br>
<br>
"*** [wb_test] Requested JED, 2460688.77 not within ephemeris
limits, 2442384.50 2460688.50 ***"<br>
<br>
The upper end JD of 2460688.50 (in January 2025) remained
unchanged despite increasing the CALC5Server.c limit of 5000
entries to 15000.<br>
<br>
The data come from this JPL ephemeris file included in DiFX
calc9.1:<br>
<br>
<a
href="https://github.com/difx/difx/raw/refs/heads/main/applications/calcserver/data/JPLEPH"
moz-do-not-send="true" class="moz-txt-link-freetext">https://github.com/difx/difx/raw/refs/heads/main/applications/calcserver/data/JPLEPH</a><br>
<br>
The file is DE403. The header says Final Epoch = 2199 Jun
22. This is consistent with the info at <a
href="https://ssd.jpl.nasa.gov/planets/eph_export.html"
moz-do-not-send="true" class="moz-txt-link-freetext">https://ssd.jpl.nasa.gov/planets/eph_export.html</a>
which states<br>
<br>
<pre
style="box-sizing:border-box;overflow:auto;font-family:Menlo,Monaco,Consolas,"Courier New",monospace;font-size:14px;padding:10px;margin-top:0px;margin-bottom:10.5px;line-height:1.42857;word-break:initial;color:rgb(51,51,51);background-color:rgb(245,245,245);border:1px solid rgb(204,204,204);border-radius:4px">DE403 : Created May 1993; includes nutations and librations.
Referred to the International Celestial Reference Frame.
Covers JED 2305200.5 (1599 APR 29) to JED 2524400.5 (2199 JUN 22).</pre>
I'd imagine the DE403 file ought to have data up till year 2199,
even if the model were already degraded/inaccurate for this
particular January 2025 VLBI track on which calc9.1 fails.<br>
<br>
Editing the Fortran calc9.1
cpepu.f with newer subroutines from difxcalc11 cpepu.f such that
it could read DE421, I tried that today, but failed miserably at
it ...<br>
<br>
The cpepu.f files of the respective DiFX calc versions are under<br>
<br>
<a
href="https://github.com/difx/difx/tree/main/applications/calcserver/calc9.1/"
moz-do-not-send="true" class="moz-txt-link-freetext">https://github.com/difx/difx/tree/main/applications/calcserver/calc9.1/</a><br>
<a
href="https://github.com/difx/difx/tree/main/applications/difxcalc11/src/"
moz-do-not-send="true" class="moz-txt-link-freetext">https://github.com/difx/difx/tree/main/applications/difxcalc11/src/</a><br>
<br>
But is it worth the effort to merge cpepu.f updates to gain
DE421 support? It looks like a lot of changes would be needed...<br>
<br>
Wouldn't the easiest(?) be to have cpepu.f (or the DiFX JPLEPH
file) accept VLBI observation dates up till the DE403 Final
Epoch JED 2524400.5 (2199)? Regardless of quality of DE403?
Erroring out with a "not within ephemeris limits" seems
misplaced for non-planetary VLBI observations. For planetary
VLBI observations, one would then just have to know and choose
difxcalc11 which has DE421... :P<br>
<br>
kind regards,<br>
Jan</div>
<div dir="ltr">
<div dir="ltr"><br>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, Jan 22, 2025 at
2:36 PM David Gordon via Difx-users <<a
href="mailto:difx-users@listmgr.nrao.edu" target="_blank"
moz-do-not-send="true" class="moz-txt-link-freetext">difx-users@listmgr.nrao.edu</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div>Maybe I can help here. I haven't looked at calc 9 in
many years and don't have a copy of it. <br>
</div>
<div>If someone can provide me a copy of calc9/calcif2 I
will take a look at it. The JPL ephemerises</div>
<div>are made using software and ascii files from a JPL
web site. I forget which JPL ephemeris is</div>
<div>used by calc9 - DE405 maybe? I can look to see if
that can be extended, but it's unlikely</div>
<div>since DE405 is obsolete. Difxcalc uses DE421, which
expires in 2050, so it will need to be</div>
<div>replaced sometime also. Probably the best quick fix
would be to replace the relevant subroutines </div>
<div>in calc9 with the ones used by difxcalc (in file
cpepu.f), and then use DE421. Some </div>
<div>parameters would also need to be changed. Another
issue is I believe calc9 is Fortran77</div>
<div>while calc11 is Fortran90. Just renaming it cpepu.f90
might be enough though for the compiler.</div>
<div><br>
</div>
<div>So, Jan, if you can send me calc9/calcif2 or where to
get it, I will try to work on this in the <br>
</div>
<div>next few days. Better to contact me at my USNO Email
- <a href="mailto:david.gordon126.civ@us.navy.mil"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">david.gordon126.civ@us.navy.mil</a>.</div>
<div><br>
</div>
<div>Regards,</div>
<div>David<br>
</div>
<div><br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Jan 21, 2025 at
4:28 PM Jay Blanchard via Difx-users <<a
href="mailto:difx-users@listmgr.nrao.edu"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">difx-users@listmgr.nrao.edu</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div>Sorry Jan I don't know enough about the formats
but just in case it is the same - here is JPLEPH.421
that we use for SCHED.</div>
<div>I assume it is not the same? <br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, 21 Jan 2025
at 09:58, Michael Dutka via Difx-users <<a
href="mailto:difx-users@listmgr.nrao.edu"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">difx-users@listmgr.nrao.edu</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">Hi Jan,<br>
We just updated the tables dfixcalc11 uses with
more stations they're attached here. Hope these
help!<br>
-Mike<br>
<br>
<br>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Jan 21,
2025 at 9:49 AM Jan Wagner via Difx-users <<a
href="mailto:difx-users@listmgr.nrao.edu"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">difx-users@listmgr.nrao.edu</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">Hi list,<br>
<br>
the old CALC 9.1 model behind DiFX 'calcif2'
comes with two data files, JPLEPH
and Horizons.lis.<br>
<br>
Unfortunately, the file JPLEPH file is
"broken" in the sense that the ephemerides
data contained in it ended already on 12th
January 2025.<br>
<br>
For VLBI experiments after that date, the
calcif2 processing needed prior to correlation
does not work - not even for VLBI experiments
without local planetary objects.<br>
<br>
Perhaps someone on the list would be able to
generate a corrected file?<br>
<br>
John Benson created the current file at NRAO
more than 10 years ago. Unfortunately, he is
not at NRAO anymore, perhaps retired.<br>
<br>
A move to difxcalc11 to replace calcif2 is
possible, but the ocean loading tables in it
are incomplete. They are missing a lot of
stations, difxcalc11 complains. It'd be more
convenient if calcif2 could work for a while
longer - with a fixed JPLEPH file.<br>
<br>
Many thanks,<br>
kind regards,<br>
Jan</div>
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<div><br clear="all">
</div>
<div><br>
</div>
<span class="gmail_signature_prefix">-- </span><br>
<div dir="ltr" class="gmail_signature">
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div>Dr. Michael S. Dutka</div>
<div>US Navy (civilian)</div>
<div>USNO Phone Number- 202-762-0242</div>
<div>Cell- 301-996-3588</div>
<div> </div>
</div>
</div>
</div>
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<fieldset class="moz-mime-attachment-header"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
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</pre>
</blockquote>
<pre class="moz-signature" cols="72">--
Geoff Crew
MIT Haystack Observatory
<a class="moz-txt-link-abbreviated" href="mailto:gbc@mit.edu">gbc@mit.edu</a>
(Do not use: gbc@haystack ; <a class="moz-txt-link-abbreviated" href="mailto:gbc@alum.mit.edu">gbc@alum.mit.edu</a> should now also work)</pre>
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