[IGSMAIL-41] IGS Status Report, July 10, 1992
Gerhard
Gerhard
Sat Jul 11 13:37:45 PDT 1992
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IGS Electronic Mail 11-JUL-1992 13:37:45 Message Number 41
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THIS FILE CONTAINS 3 MESSAGES
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>From: Gerhard Beutler
Subject: IGS Status Report, July 10, 1992
--------------------------------
IGS Status Report, July 10, 1992
________________________________
General Remarks :
- The IGS campaign 1992 started three weeks ago.
- The data flow seems to be pretty well established by now. Since I
heard no complaints I conclude that the transmission of 30 sec data
for (more or less) the entire core network does not pose serious
problems.
- First results were produced by four processing centers : In the
first IGS'92 Earth Orientation Bulletin (IGS Message No. 38) four
processing centers, namely Code (Bern), CSR (Austin),
JPL(Pasadena), and SIO (San Diego) presented their first sets of
erp-s.
- It is therefore clear that not only earth orientation parameters
but also orbits were computed from at least four processing
centers. On the other hand only data from one processing center
are available in the subdirectory GPS1:[PRODUCTS].
I INVITE ALL PROCESSING CENTERS TO DEPOSIT THEIR RESULTS AT
CDDIS (contact Carey Noll for details, compare also Carey Noll's
report in IGS message No. 3, message No. 16 for name conventions).
As soon as orbits from several agencies are available at CDDIS
Clyde Goad will start comparing them.
- Still the processing centers have to work with a delay of about 6-8
days between the last observation and the processing, because not
all the data are available - as expected - within 3 days. Let us
keep in mind that prior to the campaign we considered timeliness
of data transfer as (one of) the vital issues.
(1) 1992 Epoch Campaign
___________________
- The 1992 Epoch Campaign will start in two weeks, the exact dates
are:
25 July 0:00 UT - 8 August 23:59:59 UT (1992)
- From the experiences gained so far we can expect that high
precision global orbits stemming from different institutions will
be available at CDDIS shortly after Epoch'92.
- I believe that for most experiments scheduled under the label
"Epoch'92" it will be possible to perform the final analysis on
the 0.01-0.03 ppm level without further orbit improvement (using
precise IGS orbits).
- Let me remind you that Epoch'92 will deal with 30-sec-data.
Most analysis centers dealing with Epoch'92 rely on the
availability of 30-sec-data from the core sites too. As far as I
can see most core sites produce 30 sec data already now. Please
make sure that all core sites will use this sampling rate at
least during Epoch'92).
- I hope that the regional coordinators will give an overview of
the activities in their spheres of influence prior to the campaign
through IGS mail.
- Be careful when combining receivers of different type. To avoid
difficulties with Selective Availability (SA) all receivers should
be synchronized with GPS time within a few milliseconds.
(2) IGS and the Ionosphere
______________________
- I was approached from different sides to clarify the IGS oversight
committee's policy concerning the ionosphere.
- Let me mention in particular the workshop "Observing the
Ionosphere with GPS" which took place on April 27-28 at the
Institut fr Erdmessung in Hannover. The purpose of the workshop
was to stimulate/initiate a discussion between GPS experts on the
one hand and atmosphere specialists on the other hand. Lambert
Wanninger from Hannover wrote a summary of this informative
meeting (L. Wanninger, May 1992 "Workshop on Observing the
Ionosphere with GPS", IfE-Memo WA-05/92).
Let me try to summarize the essential information :
- Obviously there is an increasing interest from geophysicists
to use GPS for ionosphere studies.
- The IGS core network with dual frequency P-code receivers is an
excellent data set for ionosphere studies (too).
- The Wanninger report contains a proposal to the IGS oversight
committee to extend the list of IGS products to include
information concerning the ionosphere. In particular site and
even satellite specific estimates of the total electron content
(TEC) with a high temporal resolution is requested.
- Let me specify my personal position :
- I am convinced that a routine analysis of the ionosphere
should be part of the future International GPS Service.
- I agree that the 1992 IGS campaign is a phantastic test data
set to show the power of GPS for analyzing the ionosphere.
- I know that some processing centers are developing tools to
analyze the ionosphere (among them our institute).
- On the other hand I believe that it is not possible to agree
upon type and format of such products before the end of the
1992 test campagn.
- Let me therefore suggest the following :
- We invite the geophysicists interested in the ionosphere to
use the material of the 1992 IGS campaign for test studies.
- Those already working with IGS data (or wishing to do so) are
advised to coordinate their efforts with the Wanninger group.
- At the next official IGS oversight committee meeting (scheduled
for 15/16 October at Goddard, but not yet confirmed) this topic
will be addressed and a solution will be sought.
- I would like to point out that this is a suggestion. Please let me
know your opinion. I would like to give an answer to Lambert in the
next 2-3 weeks.
Kind regards
Gerhard Beutler
Tim Springer
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>From: Carey Noll
Subject: CDDIS GPS Data Holdings for IGS Week 2/GPS Week 651
---------------------------------------------------
Current CDDIS IGS GPS Data Holdings (as of 10-Jul-92 12:07)
1992 IGS Week 3/GPS Week 651 (June 28 thru July 04, 1992; Days 180 thru 186)
1 1 1 1 1 1 1
Mon. 8 8 8 8 8 8 8 No.
Site Name Name Receiver 0 1 2 3 4 5 6 Sites
------------------ ---- ---------- - - - - - - - -----
Albert Head ALBH ROGUE X X X X X X X 7
Algonquin ALGO ROGUE X X X X X X X 7
Fairbanks FAIR ROGUE X X X X X X X 7
Goldstone DS10 ROGUE X X X X X X X 7
Graz GRAZ ROGUE X X X X X X X 7
Hartebeesthoek HART ROGUE X X X X X 5
Herstmonceux HERS ROGUE X X X X X X X 7
Hobart HOBA MINIMAC X X X X X X 6
Kokee Park KOKB ROGUE X X X X X X 6
Kootwijk KOSG ROGUE X X X X X X X 7
Madrid DS60 ROGUE X X X X X X X 7
Mas Palomas MASP ROGUE X X X X X X X 7
Matera MATE ROGUE X X X X X X X 7
McMurdo MCMU ROGUE X X X X X 5
Metsahovi METS ROGUE X X X X X X X 7
Mojave MOJ1 MINIMAC X X X X X X X 7
Ny Alesund NYAL/NALL ROGUE X X X X X X X 7
Onsala ONSA ROGUE X X X X X X X 7
Pamate PAMA ROGUE X X X X X 5
Pasadena MESA ROGUE X X X X X X 6
Penticton DRAO ROGUE X X X X X X X 7
Pinyon Flat PINY ROGUE X X X X X X X 7
Richmond RCMA MINIMAC X X X X X X X 7
Saint John's STJO ROGUE X X X X X X X 7
Santiago SANT ROGUE X X X X X X 6
Taiwan TAIW ROGUE X X X X X X X 7
Tidbinbilla DS40 ROGUE X X X X X X X 7
Townsville TOWN TRIMBLE X X X X X X X 7
Tromso TROM ROGUE X X X X X X X 7
Tsukuba TSUK MINIMAC X X X X X X X 7
Usuda USUD ROGUE X X X X X X X 7
Victoria PGC1 ROGUE X X X X X X 6
Wellington WELL TRIMBLE X X X X X X X 7
Westford WES1 MINIMAC X X X X X X X 7
Wettzell WETT ROGUE X X X X X X X 7
Yaragadee YAR1 ROGUE X X X X X X X 7
Yellowknife YELL ROGUE X X X X X X X 7
Zimmerwald ZIMM TRIMBLE X X X X X X X 7
------------------ ---- ---------- -- -- -- -- -- -- -- -----
Totals: 38 stations 36 36 36 37 38 36 36 255
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>From: Tom Clark, NASA/GSFC
Subject: VLBI's Plans during EPOCH 92
----------------------------
Several people have asked about VLBI data that will be available during
the "EPOCH 92" period in late July and early August. The following is
extracted from the Master VLBI List which we maintain here at NASA/GSFC
and contains all the 1+ day observing sessions planned by all the inter-
national groups for the period 13 July thru 20 August. The TIME column
is the experiment UTC starting time.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
EXPERIMENT DATE TIME DUR STATIONS
--------------------------------------------------------
Pol-749 13-JUL 08:00 24h Wf-Mo-Ri-Wz-Ag-Fb (Post-Quake Special)
PPM-S1 15-JUL 16:00 24h Fb-Ka-Ks-Ti-Sc-Cn
NAVNET-185 16-JUL 18:00 24h Fb-Gb-Ka-Ri
PHASE-DELAY2 16-JUL 21:00 24h Fv-Pt-La
IRIS-P64 17-JUL 20:00 24h Fb-Ka-K4-Ta
Pol-750 20-JUL 08:00 24h Wf-Os-Fb-Wz-Hf
SH-S32 20-JUL 16:00 24h Ta-Hb-Sc
GLOBAL 21-JUL 20:00 48h Wz-Sc-Fb-Wf-Ka-Ks-Ta-Hb-Cn
HOFN-2 22-JUL 08:00 24h Hf-Ri-Os
NAVNET-186 23-JUL 22:00 24h Fb-Gb-Ka-Ri
HOFN-3 25-JUL 04:00 24h Hf-Wz-Os-Wf-Fb
HOFN-4 26-JUL 06:00 24h Hf-Wz-Os-Wf-Fb
> Pol-751 27-JUL 08:00 24h Hf-Wz-Os-Wf-Fb
> NAVEX-G3 28-JUL 08:00 26h Sc-Mt-Hb-Gb-K4
> EXT-R&D-A 28-JUL 10:00 26h Fb-Ka-Wf-Wz-La-Fv
> NAVEX-G4 29-JUL 12:00 30h Sc-Mt-Hb-Gb-K4-Ag
> EXT-R&D-B 29-JUL 14:00 26h Fb-Ka-Wf-Wz-La-Fv
> NAVNET-187 30-JUL 18:00 24h Fb-Gb-Ka-Ri
> EXT-R&D-C 31-JUL 20:00 28h Fb-Ka-Wf-Wz-La-Fv
MARK-4 Test 01-AUG TBD TBD Wf(or Ha)-Gf
> EXT-R&D-D 02-AUG 02:00 28h Fb-Ka-Wf-Wz-La-Fv
> Pol-752 03-AUG 08:00 24h Wf-Mo-Ri-Wz-Ag
> NAVEX-G5 04-AUG 08:00 26h Sc-Mt-Hb-Gb-K4
> EXT-R&D-E 04-AUG 10:00 26h Fb-Ka-Wf-Wz-La-Fv
> NAVEX-G6 05-AUG 12:00 30h Sc-Mt-Hb-Gb-K4-Ag
> EXT-R&D-F 05-AUG 14:00 26h Fb-Ka-Wf-Wz-La-Fv
> NAVNET-188 06-AUG 18:00 24h Fb-Gb-Ka-Ri
> EXT-R&D-G 07-AUG 20:00 28h Fb-Ka-Wf-Wz-La-Fv
> EXT-R&D-H 09-AUG 02:00 28h Fb-Ka-Wf-Wz-La-Fv
> Pol-753 10-AUG 08:00 24h Wf-Mo-Ri-Wz-Ag
> SH-S33 10-AUG 14:00 24h Ta-Hb-Sc
> NAVEX-25 10-AUG 18:00 24h Fb-Gb-Ka-Mt-K4
XASIA-2 11-AUG 16:00 24h Wz-Hb-Ti-Ks-Cn-Ta
TROMSO-1 12-AUG 18:00 24h Ts-Wz-Os-Wf-Fb
NAVNET-189 13-AUG 18:00 24h Fb-Gb-Ka-Ri
TROMSO-2 15-AUG 04:00 24h Ts-Wz-Os-Wf-Fb
TROMSO-3 16-AUG 06:00 24h Ts-Wz-Os-Wf-Fb
Pol-754 17-AUG 08:00 24h Ts-Wz-Os-Wf-Fb
PHASE-DELAY3 17-AUG 16:00 24h Fv-Pt-La
IRIS-S57 18-AUG 16:00 24h Wf-Ri-Wz-Hb-Sc
FRAME-57 18-AUG 18:00 24h Fb-Gb-Ka-Ag
TROMSO-5 19-AUG 18:00 24h Ts-Wz-Os-Wf-Fb
NAVNET-190 20-AUG 18:00 24h Fb-Gb-Ka-Ri
STATION CODES:
Ag - Algonquin Park Mt - Matera
Cn - China Nt - Noto
D5 - DSS15 Nl - North Liberty/VLBA
Fb - Fairbanks Oh - O'Higgins
Fv - Fort Davis/VLBA Om - Onsala (MV-2)
Gb - Green Bank 85-3 Os - Onsala
Gf - GGAO (MV-3) Ov - Owens Valley
Hb - HartRAO Pt - Pie Town
Hf - Hofn (MV-2) Ri - Richmond
Ho - Hohenspeissenberg (MV-2) Sc - Santiago
Hs - Haystack Ta - Tasmania
Ka - Kauai TBD - To Be Determined
Ki - Kirschberg (MV-2) Ti - DSS45 (Australia)
Kp - Kitt Peak Tr - Trysil (MV-2)
Ks - Kashima (26m) Ts - Tromso (MV-2)
K4 - Kashima (34m) Us - Ussuriisk
La - Los Alamos Wf - Westford
Ma - DSS65 (Madrid) Wz - Wettzell
Md - Medicina Yk - Yellowknife
Mo - Mojave
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pay special note of the lines beginning ">" during the July 27 - August 10
period. During this time, the NASA-sponsored Extended R&D sessions, plus
scheduled POLARIS/IRIS sessions, plus the augmented USNO NAVNET/NAVEX programs
will provide essentially continuous coverage on two simultaneous VLBI
networks.
Concerning the R&D experiments -- in these measurements we pull out all the
stops and use the strongest network we can form with the most optimum
observing schedule we can generate. The more routine POLARIS/IRIS and
NAVNET sessions are "operational" and are more conservative.
As a prediction of VLBI performance, a comparison of representative data,
analyzed under the assumption of perfect site and source positions, for
a 24-hour period shows the following one-sigma uncertainties:
X-pole Y-pole UT1
milliarcseconds usec of time
R&D 0.08 0.07 3
IRIS 0.14 0.13 6
NAVNET 0.17 0.18 9
If the analysis is modified to allow piecewise-linear variation of the EOP
in intervals of 4 hours so that sub-daily variations can be studied, these
values approximately double to
R&D 0.18 0.17 7
IRIS 0.31 0.30 16
NAVNET 0.35 0.40 20
(thanks to Dan MacMillan and Chopo Ma for doing the work to produce these
predictions. Marshall Eubanks indicates that his analysis of NAVNET data
shows that the sub-daily uncertainties scale approximately as 1/sqrt(t)
from 24 hours down to about 1 hour -- in this case sqrt(6) ~ 2.4 in
reasonable agreement with Dan & Chopo's result.)
We look forward to having the simultaneous GPS and VLBI data to compare
short- and long-term performance. Good Luck!
Tom Clark
P.S. Serious budget problems have forced NASA & NOAA to close down Mojave
as of September. Most of the Mojave staff have already departed. You will
note that the network we are using for the R&D measurements no longer
includes Mojave at all. This is a change from the information we had
given out earlier.
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