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Bulletin

CDDIS Bulletin - April 1997
Volume 12 No. 4

In this issue:

About the cover: The map on the cover of this issue of the CDDIS Bulletin shows the current global IGS network using the Berghaus Star projection, a decorative, modified azimuthal map projection.

GPS Tracking Data Summary and Access Statistics for 1996

The CDDIS has supported the International GPS Service for Geodynamics (IGS) as a global data center since its start in June 1992. During 1996, the CDDIS routinely archived data from over 110 sites, averaging nearly two Gbytes in compressed data volume per month. Nearly 40,000 observation days were archived from 126 distinct sites. Table 1 below lists the GPS tracking sites archived in the CDDIS during 1996. Figure 1 illustrates the amount of data transferred to/from the CDDIS during 1996. Over one million files were transferred in 1996, totalling approximately 360 Gbytes in volume. Averaging these figures, users transferred 85K files per month, totalling nearly 30 Gbytes in size. The chart in Figure 2 details the total number of host accesses per month with the number of distinct (i.e., unique) hosts per month shown as an overlay. Here, a host access is defined as an initiation of an ftp session; this session may transfer a single file, or many files. Figure 3 illustrates the profile of users accessing the system during 1996; these figures represent the number of distinct hosts in a particular country or organization. Approximately one third of the users of GPS data available from the CDDIS come from U.S. government agencies, universities, or corporations.

Table 1. CDDIS Fixed GPS Network Data Holdings for 1996 -- Update

Site Name

Latitude

Longitude

Mon.
Name

Receiver Type

Start Date

End Date

No.
Days
Albert Head

48° 23'

-123° 29'

ALBH

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
366
Algonquin

45° 57'

-78° 04'

ALGO

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
366
Ankara

39° 53'

32° 45'

ANKR

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
267
Annapolis

38° 36'

76° 18'

USNA

 ROGUE SNR-8000

13-Jan-96

31-Dec-96
354
AOA, Westlake

34° 10'

-118° 50'

AOA1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
350
Arequipa

-16° 28'

-71° 38'

AREQ

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
339
Ascension Island

-07° 58'

-14° 49'

ASC1

 ROGUE SNR-8000

21-Apr-96

31-Dec-96
247
Auckland

-35° 33'

174° 28'

AUCK

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
360
Azusa

34° 07'

-117° 54'

AZU1

 ROGUE SNR-8000

26-Jul-96

31-Dec-96
97
Bahrain

26° 13'

50° 37'

BAHR

 ASHTECH Z-XIID

23-Jun-96

31-Dec-96
181
Bangalore

12° 59'

77° 40'

IISC

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
254
Bermuda

32° 21'

-64° 39'

BRMU

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
365
Bishkek

42° 32'

74° 28'

POL2

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
292
Bogotá

04° 38'

-74° 05'

BOGT

 ROGUE SNR-8000

19-Feb-96

12-Dec-96
230
Borowiec

52° 17'

17° 05'

BOR1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
363
Brasília

-15° 57'

-47° 53'

BRAZ

 ROGUE SNR-8000

29-Aug-96

31-Dec-96
108
Brussels

50° 18'

04° 13'

BRUS

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
354
Carr Hill

35° 53'

-120° 26'

CARR

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
361
Casey

-66° 16'

110° 32'

CAS1

 ROGUE SNR-8100

01-Jan-96

31-Dec-96
295
Catalina Island

32° 13'

-118° 12'

CAT1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
364
Chatham Island

-43° 58'

-176° 34'

CHAT

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
365
Churchill

58° 27'

-94° 00'

CHUR

 ROGUE SNR-8000

18-Jun-96

31-Dec-96
184
CIT, Pasadena

34° 09'

-118° 08'

CIT1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
366
Cocos Island

-12° 12'

96° 50'

COCO

 ROGUE SNR-8100

13-Jun-96

31-Dec-96
147
Davis

-68° 34'

77° 58'

DAV1

 ROGUE SNR-8100

02-Feb-96

29-Dec-96
266
Diego Garcia

-07° 12'

72° 15'

DGAR

 ROGUE SNR-8000

09-May-96

31-Dec-96
235
Easter Island

-27° 09'

-109° 23'

EISL

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
342
Ensenada

31° 15'

-116° 09'

CICE

 ROGUE SNR-8000

03-Jan-96

31-Dec-96
348
Fairbanks

64° 58'

-147° 29'

FAIR

 ROGUE SNR-8

01-Jan-96

16-Apr-96
106
  ROGUE SNR-8000

17-Apr-96

31-Dec-96
258
Flin Flon

54° 44'

-101° 59'

FLIN

 ROGUE SNR-8000

08-Jun-96

31-Dec-96
206
Fortaleza

-03° 45'

-38° 35'

FORT

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
363
Galapagos Island

00° 54'

-89° 03'

GALA

 ROGUE SNR-8000

29-Mar-96

31-Dec-96
164
Goldstone

35° 15'

-116° 47'

GOL2

 ROGUE SNR-8000

29-May-96

31-Dec-96
214
 

GOLD

 ROGUE SNR-8

01-Jan-96

30-Dec-96
342
Grasse

43° 45'

06° 55'

GRAS

 ROGUE SNR-12 RM

03-Oct-96

31-Dec-96
78
  ROGUE SNR-8100

01-Jan-96

06-May-96
127
Graz

47° 04'

15° 30'

GRAZ

 ROGUE SNR-8

01-Jan-96

24-Jun-96
175
  ROGUE SNR-8000

25-Jun-96

31-Dec-96
189
Greenbelt

39° 01'

-76° 50'

GODE

 ROGUE SNR-8100

01-Jan-96

31-Dec-96
350
Guam

13° 28'

144° 45'

GUAM

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
365
Hartebeesthoek

-25° 53'

27° 42'

HART

 ROGUE SNR-8

01-Jan-96

03-Mar-96
61
  ROGUE SNR-8000

29-Apr-96

31-Dec-96
220
 

HRAO

 ROGUE SNR-8000

27-Sep-96

19-Nov-96
53
Harvest Platform

34° 28'

-120° 41'

HARV

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
358
Herstmonceux

50° 52'

00° 20'

HERS

 ROGUE SNR-8C

01-Jan-96

31-Dec-96
361
Hobart

-42° 48'

147° 26'

HOB2

 ROGUE SNR-8100

06-Feb-96

31-Dec-96
236
Horn Point

38° 36'

-76° 08'

HNPT

 ROGUE SNR-12 RM

01-Jan-96

31-Dec-96
366
Irkutsk

52° 18'

104° 15'

IRKT

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
354
Jozefoslaw

51° 02'

21° 30'

JOZE

 TRIMBLE 4000SSE

01-Jan-96

31-Dec-96
360
Kellyville

66° 59'

-50° 57'

KELY

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
298
Kerguelen

-49° 21'

70° 16'

KERG

 ROGUE SNR-8C

01-Jan-96

31-Dec-96
357
Kiruna

67° 32'

20° 09'

KIRU

 ROGUE SNR-8100

01-Jan-96

31-Dec-96
365
Kitab

39° 08'

66° 53'

KIT3

 ROGUE SNR-8000

01-Jan-96

30-Dec-96
333
Kokee Park

22° 08'

-159° 40'

KOKB

 ROGUE SNR-8000

11-Jan-96

31-Dec-96
353
Kootwijk

52° 11'

05° 49'

KOSG

 ROGUE SNR-12

02-Feb-96

31-Dec-96
333
  ROGUE SNR-8

01-Jan-96

01-Feb-96
27
Kourou

05° 08'

-52° 37'

KOUR

 ROGUE SNR-8C

01-Jan-96

31-Dec-96
360
Kwajalein

09° 24'

167° 29'

KWJ1

 ROGUE SNR-8000

17-Mar-96

31-Dec-96
280
L'Ebre

40° 82'

00° 49'

EBRE

 TRIMBLE 4000SSE

29-Jan-96

30-Dec-96
160
La Plata

-34° 31'

-57° 33'

LPGS

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
338
Lac du Bonnet

50° 16'

-95° 52'

DUBO

 ROGUE SNR-8000

18-Oct-96

31-Dec-96
75
Lhasa

29° 25'

91° 07'

LHAS

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
303
Limon

09° 59'

-83° 06'

MOIN

 ROGUE SNR-8000

25-Feb-96

30-Dec-96
54
Long Beach

33° 28'

-118° 09'

LBCH

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
364
Macquarie Island

-54° 30'

158° 56'

MAC1

 ROGUE SNR-8100

01-Jan-96

31-Dec-96
193
Madrid

40° 26'

-04° 15'

MADR

 ROGUE SNR-8

01-Jan-96

31-Dec-96
362
Malindi

-03° 14'

40° 08'

MALI

 ROGUE SNR-8C

01-Jan-96

31-Dec-96
343
Mammoth Lakes

37° 38'

-118° 57'

CASA

 ROGUE SNR-8000

01-Jan-96

29-Dec-96
333
 

KRAK

 ROGUE SNR-8000

25-Jul-96

25-Dec-96
141
Maspalomas

27° 46'

-15° 38'

MAS1

 ROGUE SNR-12 RM

18-Apr-96

31-Dec-96
253
  ROGUE SNR-8100

01-Jan-96

17-Apr-96
96
Matera

40° 39'

16° 42'

MATE

 ROGUE SNR-8

01-Jan-96

08-Jul-96
190
  ROGUE SNR-8100

09-Jul-96

31-Dec-96
176
Mauna Kea

19° 48'

-155° 28'

MKEA

 ROGUE SNR-12 RM

10-Oct-96

31-Dec-96
82
  ROGUE SNR-8000

27-Sep-96

09-Oct-96
13
McDonald

30° 41'

-104° 01'

MDO1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
359
McMurdo

-77° 51'

166° 40'

MCM4

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
361
Mendeleevo

37° 14'

56° 02'

MDVO

 TRIMBLE 4000SSE

01-Jan-96

31-Dec-96
363
Metsahovi

60° 13'

24° 24'

METS

 ROGUE SNR-8100

01-Jan-96

31-Dec-96
345
Monument Peak

32° 53'

-116° 25'

MONP

 ASHTECH LPZ-XII

01-Jan-96

30-Dec-96
355
Mount Wilson

34° 13'

-118° 04'

WLSN

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
337
North Liberty

41° 46'

-91° 34'

NLIB

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
356
Northridge

34° 15'

-118° 31'

CSN1

 ROGUE SNR-8000

02-May-96

31-Dec-96
243
Ny Ålesund

78° 56'

11° 52'

NYAL

 ROGUE SNR-8

01-Jan-96

31-Dec-96
348
O'Higgins

-63° 19'

-59° 54'

OHIG

 ROGUE SNR-8000

12-Jan-96

31-Dec-96
347
Oatt Mountain

34° 20'

-118° 36'

OAT2

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
366
Oberpfaffenhofen

48° 05'

11° 17'

OBER

 ROGUE SNR-8000

27-Oct-96

31-Dec-96
62
Onsala

57° 24'

11° 56'

ONSA

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
362
Palos Verdes

33° 45'

-118° 24'

PVEP

 TRIMBLE 4000SSE

01-Jan-96

31-Dec-96
360
Pamate

-17° 34'

-149° 34'

PAMA

 ROGUE SNR-8100

01-Jan-96

31-Dec-96
354
Pasadena

34° 12'

-118° 10'

JPLM

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
357
Penticton

49° 19'

-119° 37'

DRAO

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
366
Perth

-31° 58'

115° 49'

PERT

 ROGUE SNR-8100

01-Jan-96

31-Dec-96
362
Pie Town

34° 18'

-108° 07'

PIE1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
366
Pinyon Flat

33° 37'

-116° 27'

PIN1

 ASHTECH Z-XIID

01-Jan-96

31-Dec-96
347
Potsdam

52° 23'

13° 04'

POTS

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
363
Quincy

39° 58'

-120° 56'

QUIN

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
364
Reykjavík

64° 09'

-22° 00'

REYK

 ROGUE SNR-8000

12-Jan-96

31-Dec-96
348
Richmond

25° 37'

-80° 23'

RCM5

 ROGUE SNR-8000

01-Jan-96

03-Nov-96
276
 

RCM6

 ROGUE SNR-8000

01-Nov-96

31-Dec-96
58
Saddle Peak

34° 04'

-188° 39'

SPK1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
355
Saint John's

47° 36'

-52° 41'

STJO

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
359
San Nicolas Isl.

33° 15'

-119° 31'

SNI1

 ROGUE SNR-8000

01-Jan-96

28-Jul-96
58
Santiago

-33° 09'

-70° 40'

SANT

 ROGUE SNR-8

01-Jan-96

18-May-96
132
  ROGUE SNR-8000

17-Jul-96

10-Sep-96
50
  ROGUE SNR-8100

11-Sep-96

31-Dec-96
112
Scripps

32° 52'

-117° 15'

SIO3

 ASHTECH Z-XII3

01-Jan-96

31-Dec-96
357
Seychelles

-04° 41'

55° 30'

SEY1

 ROGUE SNR-8000

03-Jan-96

11-Feb-96
20
Shanghai

31° 11'

121° 26'

SHAO

 ROGUE SNR-8100

01-Jan-96

31-Dec-96
355
Solomons Island

38° 19'

-76° 27'

SOL1

 ROGUE SNR-8000

06-Mar-96

31-Dec-96
300
  TRIMBLE 4000SSE

01-Jan-96

05-Mar-96
59
St. Croix

17° 45'

-64° 35'

CRO1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
364
Taejon

36° 12'

127° 16'

TAEJ

 TRIMBLE 4000SSE

01-Jan-96

01-Jan-97
357
Taipei

25° 01'

121° 32'

TAIW

 ROGUE SNR-800

01-Jan-96

31-Dec-96
362
Thule

76° 21'

-68° 18'

THU1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
363
Tidbinbilla

-35° 24'

148° 59'

TID2

 ROGUE SNR-8000

26-Jul-96

31-Dec-96
159
 

TIDB

 ROGUE SNR-8

01-Jan-96

31-Dec-96
365
Tromsø

69° 40'

18° 56'

TROM

 ROGUE SNR-8

01-Jan-96

31-Dec-96
344
Tsukuba

36° 06'

140° 05'

TSKB

 ROGUE SNR-8100

01-Jan-96

31-Dec-96
366
UCLA, Los Angeles

34° 04'

-118° 27'

UCLP

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
366
USC, Los Angeles

34° 01'

-118° 18'

USC1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
357
Usuda

36° 08'

138° 22'

USUD

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
366
Vandenberg

34° 34'

-120° 30'

VNDP

 ASHTECH LPZ-XII

01-Jan-96

31-Dec-96
353
Villafranca

42° 11'

-01° 27'

VILL

 ROGUE SNR-8100

01-Jan-96

31-Dec-96
365
Westford

42° 37'

-71° 29'

WES2

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
364
Wettzell

49° 09'

12° 53'

WETT

 ROGUE SNR-800

01-Jan-96

31-Dec-96
363
 

WTZR

 ROGUE SNR-8000

10-Jan-96

31-Dec-96
354
Whitehorse

60° 43'

-135° 05'

WHIT

 ROGUE SNR-8000

07-Jun-96

31-Dec-96
201
Whittier College

33° 59'

-118° 02'

WHC1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
351
Whittier Library

33° 59'

-118° 02'

WHI1

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
363
Wuhan

30° 35'

114° 19'

WUHN

 ROGUE SNR-8000

03-Jan-96

30-Dec-96
272
Xi'an

34° 22'

109° 13'

XIAN

 ROGUE SNR-8000

18-May-96

31-Dec-96
178
Yaragadee

-29° 03'

115° 21'

YAR1

 ROGUE SNR-8

01-Jan-96

31-Dec-96
343
Yellowknife

62° 29'

-114° 29'

YELL

 ROGUE SNR-12

20-Dec-96

31-Dec-96
12
  ROGUE SNR-8000

01-Jan-96

18-Dec-96
353
Zimmerwald

46° 53'

07° 28'

ZIMM

 TRIMBLE 4000SSE

01-Jan-96

31-Dec-96
364
Zvenigorod

55° 24'

36° 30'

ZWEN

 ROGUE SNR-8000

01-Jan-96

31-Dec-96
348
138 occupations at 126 sites
38,289

IGS Preliminary Orbits Now Available

The International GPS Service for Geodynamics (IGS) now produces high quality, combined orbit predictions. These daily solutions, derived by the IGS Analysis Coordinator and based on contributions from the five individual analysis center predictions of AIUB, NRCan, GFZ, JPL, and SIO, are available shortly after 23:00 UTC (but no later than 23:30 UTC). These solutions are available from CDDIS since GPS week 0895 (March 02-08, 1997); the files are denoted IGPwwww7.typ, where wwww is the GPS week number, and typ is the file type (SP3 for orbit, SUM for summary, and ERP for Earth rotation parameters). All IGS predicted orbit products can be retrieved from the CDDIS in subdirectories by GPS week of the main directory GPS3:[PRODUCTS].

Analyzed Results Recently Submitted to the CDDIS

Dr. Richard Gross (JPL, email: rsg@logos.jpl.nasa.gov) has submitted his data sets of polar motion, length-of-day, and UT1-UTC values generated from several space geodetic techniques. These data can be retrieved from anonymous FTP on the CDDIS in the directory ANON_DIR:[JPL.1996]; the files available are as follows:

SPACE96. Contains polar motion and UT1-UTC values generated at one-day intervals from a combination of space geodetic measurements (VLBI, SLR, LLR, and GPS) spanning September 27, 1976 through February 07, 1997.
SPACE96.LOD Contains excess length-of-day (LOD) estimates from the combined Earth orientation series in SPACE96 spanning September 27, 1976 through February 07, 1997.
COMB96. Contains a Kalman filter combination of independent optical astrometry (BIH and ILS) measurements of the Earth's orientation with the space geodetic measurements comprising SPACE96; consists of polar motion and UT1-UTC values spanning January 20, 1962 to February 05, 1997 at five-day intervals.
COMB96.LOD Contains excess length-of-day (LOD) estimates from the combined Earth orientation series in COMB96 spanning January 20, 1962 to February 05, 1997 at five-day intervals.
POLE96. Contains a combination of optical astrometry (BIH and ILS) measurements with the space geodetic measurements comprising COMB96; consists of polar motion values spanning January 19, 1900 to January 20, 1997 at 30.4375-day intervals.

DATA BITS AND BYTES

This section is designed to give brief notices of special events, new data sets, or problems encountered in recent months. The CDDIS staff believes the user community should be informed of these problems in order to ensure that the best results possible are produced from data issued by the archive.

Time Bias in CRL Tokyo SLR Data

Toshimichi Otsubo (Communications Research Laboratory, CRL) reports that all on-site normal points from the CRL station in Tokyo (station number 7308) from February 11 through 27, 1997 have an unrecoverable time bias, up to hundreds of microseconds, because of a clock problem. CRL regrets any inconvenience this error has caused.

Epoch Timing Corrections for NASA SLR Stations

ATSC reports that three NASA SLR systems have experienced timing problems over the last few months. These problems are detailed below with listings of passes affected for each station. ATSC regrets any inconvienience this problem has caused.

TLRS-3 (Station 7403) in Arequipa, Peru. This station experienced an excessive drift rate with their station clock. This high drift rate affected all TLRS-3 taken between January 24, 1997 through March 10, 1997, inclusive. The drift rate was corrected by replacing the station clock on March 10, 1997 at 21:20 GMT. The data during this period are recoverable by applying the epoch corrections given in Table 2 below. In order to correct TLRS-3 timetags these epoch corrections must be subtracted from the normal point timetags using the equation:

corrected timetag = normal point timetag - epoch correction

Table 2. Time Corrections for TLRS-3

Date Epoch correction (microseconds)

01/24/97

1.1

01/25/97

1.5

01/26/97

2.0

01/27/97

2.4

01/28/97

2.8

01/29/97

3.3

01/30/97

3.7

01/31/97

4.1

02/01/97

4.6

02/02/97

5.0

02/03/97

5.4

02/04/97

5.8

02/05/97

5.5

02/06/97

5.1

02/07/97

4.6

02/08/97

4.2

02/09/97

3.8

02/10/97

3.4

02/11/97

2.9

02/12/97

2.5

02/13/97

2.1

02/14/97

1.6

02/15/97

1.2

02/16/97

0.8

02/17/97

0.3

02/18/97

-0.1

02/19/97

-0.5

02/20/97

-1.0

02/21/97

-1.4

02/22/97

-1.8

02/23/97

-2.2

02/24/97

-2.7

02/25/97

0.0

02/26/97

-0.4

02/27/97

-0.9

02/28/97

-1.3

03/01/97

-1.8

03/02/97

-2.2

03/03/97

-2.6

03/04/97

-3.1

03/05/97

-3.5

03/06/97

-4.0

03/07/97

-4.4

03/08/97

-4.8

03/09/97

-5.3

03/10/97

-5.7 (before 21:20)

03/10/97

0.0 (after 21:20)

MOBLAS-8 (Station 7109) in Quincy, California. This system experienced problems with their station clock affecting all MOBLAS-8 data taken between December 03, 1996 through December 16, 1996, inclusive, and January 09, 1997 and January 17, 1997, inclusive. The data during these two periods are recoverable by applying the epoch corrections given in Table 3 below. In order to correct MOBLAS-8 timetags these epoch corrections must be subtracted from the normal point timetags using the equation:

corrected timetag = normal point timetag - epoch correction

Table 3. Time Corrections for MOBLAS-8

Date Epoch correction (microseconds)

12/03/96

-1.1

12/04/96

-1.1

12/05/96

-1.2

12/06/96

-1.2

12/07/96

-1.2

12/08/96

-1.3

12/09/96

-1.3

12/10/96

-1.3

12/11/96

-1.4

12/12/96

-1.4

12/13/96

-1.5

12/14/96

-1.5

12/15/96

-1.5

12/16/96

-1.6

01/09/97

-2.4

01/10/97

-2.4

01/11/97

-2.4

01/12/97

-2.5

01/13/97

-2.5

01/14/97

-2.5

01/15/97

-2.6

01/16/97

-2.6

01/17/97

-2.6

HOLLAS (Station 7210) in Haleakala, Hawaii. This station experienced an excessive drift rate in their station clock. This high drift rate affected all HOLLAS taken between December 13, 1994 through June 14, 1995, inclusive. The drift rate was corrected by a combination of replacing the station clock and performing Cesium adjustments. The data during this period are recoverable by applying the epoch corrections given in Table 4 below. In order to correct HOLLAS timetags these epoch corrections must be subtracted from the normal point timetags using the equation:

corrected timetag = normal point timetag - epoch correction

Table 4. Time Corrections for HOLLAS

Date
Epoch correction (microseconds)
Date
Epoch correction (microseconds)

12/13/94

1.5

03/15/95

3.3

12/14/94

1.6

03/16/95

3.5

12/15/94

1.6

03/17/95

3.7

12/16/94

1.7

03/18/95

3.9

12/17/94

1.8

03/19/95

4.1

12/18/94

1.9

03/20/95

4.4

12/19/94

2.0

03/21/95

4.6

12/20/94

2.1

03/22/95

4.8

12/21/94

2.2

03/23/95

5.0

12/22/94

2.2 (before 2:55)

03/24/95

5.2

12/22/94

0.2 (after 2:55)

03/25/95

5.5

12/23/94

0.3

03/26/95

5.7

12/24/94

0.5

03/27/95

5.9

12/25/94

0.6

03/28/95

5.8

12/26/94

0.8

03/29/95

6.0

12/27/94

0.9

03/30/95

6.1

12/28/94

1.1

03/31/95

6.3

12/29/94

1.2

04/01/95

6.4

12/30/94

1.4

04/02/95

6.6

12/31/94

1.5

04/03/95

6.7

01/01/95

1.7

04/04/95

6.9

01/02/95

1.8

04/05/95

7.1

01/03/95

2.0

04/06/95

7.2

01/04/95

2.1

04/07/95

7.4

01/05/95

2.3

04/08/95

7.5

01/06/95

2.4

04/09/95

7.7

01/07/95

2.6

04/10/95

7.9

01/08/95

2.7

04/11/95

8.0

01/09/95

2.9 (before 18:20)

04/12/95

8.2

01/09/95

0.0 (after 18:20)

04/13/95

8.3

01/10/95

0.1

04/14/95

8.5

01/11/95

0.2

04/15/95

8.5

01/12/95

0.4

04/16/95

8.6

01/13/95

0.5

04/17/95

8.4

01/14/95

0.6

04/18/95

8.2

01/15/95

0.8

04/19/95

8.0

01/16/95

0.9

04/20/95

7.8

01/17/95

1.0

04/21/95

7.7

01/18/95

1.2

04/22/95

7.8

01/19/95

1.3

04/23/95

7.9

01/20/95

1.4

04/24/95

8.1

01/21/95

1.6

04/25/95

8.2

01/22/95

1.7

04/26/95

8.3

01/23/95

1.8

04/27/95

8.3

01/24/95

1.9

04/28/95

8.3

01/25/95

2.1

04/29/95

8.2

01/26/95

2.2

04/30/95

8.2

01/27/95

2.3

05/01/95

8.1

01/28/95

2.5

05/02/95

8.1

01/29/95

2.6

05/03/95

8.0

01/30/95

2.7

05/04/95

8.1

01/31/95

2.9

05/05/95

8.2

02/01/95

3.0

05/06/95

8.3

02/02/95

3.1

05/07/95

8.4

02/03/95

3.3

05/08/95

8.5

02/04/95

3.4

05/09/95

8.7

02/05/95

3.5

05/10/95

8.8

02/06/95

3.7

05/11/95

8.9

02/07/95

3.8

05/12/95

8.8

02/08/95

3.9

05/13/95

8.7

02/09/95

4.1

05/14/95

8.5

02/10/95

4.2

05/15/95

8.4

02/11/95

4.3

05/16/95

8.3

02/12/95

4.5

05/17/95

8.2

02/13/95

4.6

05/18/95

8.3

02/14/95

4.7

05/19/95

8.4

02/15/95

4.9

05/20/95

8.5

02/16/95

5.0 (before 9:00)

05/21/95

8.6

02/16/95

0.0 (after 9:00)

05/22/95

8.7 (before 16:16)

02/17/95

-0.3

05/22/95

19536.9 (after 16:16)

02/18/95

-0.6

05/23/95

19536.9

02/19/95

-0.8

05/24/95

19536.9 (before 5:27)

02/20/95

-1.1

05/24/95

-0.2 (after 5:27)

02/21/95

-1.3 (before 13:30)

05/25/95

-0.1

02/21/95

-0.1 (after 13:30)

05/26/95

0.0

02/22/95

0.2

05/27/95

0.1

02/23/95

0.4

05/28/95

0.2

02/24/95

0.7

05/29/95

0.3

02/25/95

0.9

05/30/95

0.4

02/26/95

1.2

05/31/95

0.5

02/27/95

1.4

06/01/95

0.6

02/28/95

1.7

06/02/95

0.7

03/01/95

1.9

06/03/95

0.8

03/02/95

2.2

06/04/95

0.9

03/03/95

2.1

06/05/95

1.0

03/04/95

1.9

06/06/95

1.1

03/05/95

1.8

06/07/95

1.2

03/06/95

1.7

06/08/95

1.3

03/07/95

1.6

06/09/95

1.3

03/08/95

1.7

06/10/95

1.3

03/09/95

1.9

06/11/95

1.4

03/10/95

2.2

06/12/95

1.4

03/11/95

2.4

06/13/95

1.4

03/12/95

2.6

06/14/95

1.4 (before 14:33)

03/13/95

2.8

06/15/95

0.0 (after 14:33)

03/14/95

3.0

    

SLR On-Site Normal Point Pass Totals for 1996 - Update

Table 5 on page 13 lists an update to the SLR on-site normal point pass totals for 1996 as previously published in the February 1997 issue of the CDDIS Bulletin. These figures reflect late arriving data and data base checks performed in recent weeks. As stated in the February 1997 article, these figures are based on weekly, monthly, and yearly reports and are available on CDDIS through anonymous ftp in the directory ANON_DIR:[REPORTS.SLRWEEK.yyyy] (where yyyy is the year) or through the WWW at URL ftp://cddis.gsfc.nasa.gov/reports/slrweek/ . Interested users can receive these reports automatically on a weekly basis by contacting Carey Noll (noll@cddis.gsfc.nasa.gov). We regret any confusion the previously published values may have caused.

Permanent GPS Network Update

Since the February 1997 issue of the CDDIS Bulletin, the CDDIS has archived data from the following new GPS tracking sites:

Table 6. New GPS Tracking Sites

Mon. Name

Site Name

Data Source

Receiver Type

Start Date

PPYN

Popayán, Colombia

JPL

Rogue SNR-8000

15-Mar-97


   
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Author: Carey E. Noll
Responsible NASA Official: Ed Grayzeck
Last Updated: May 27, 2005