Survey control data from the Windmill Islands 1993-94 compiled by John Hyslop

Full description

These data are held in an excel spreadsheet and are survey control points captured by Suzanne Haydon at Casey Station in 1993-1994. John Hyslop was also involved in their collection. For further information, also see the metadata record entitled: 'Survey report 1993/94 Australian Antarctic Division Author - J.Hyslop / AUSLIG'.

Several emails below (presented in chronological order from the top down) provide further information about this dataset. The emails were exchanged between Henk Brolsma and Peter Morgan.

##########################################

Brad and I have just received some gravity data from Suzanne Haydon who was a student at Melbourne University. She was part of the Windmill Islands geology team that summer, (1993-1994). Suzanne says,
--------------------------------------------------------------

Gravity Stations
Coordinates for all of the 93/94 gravity stations will be supplied by John Hyslop (AUSLIG). The gravity readings were taken at the closest possible (suitable) point to the monumented mark. The most suitable place was often near, but not over the mark. NM/S/ marks were particularly located in such unsuitable places. Stations include marks put in by several different surveys and are denoted:
AUS
NM/S/
G
BM
other
These stations are located roughly on the 1:50 000 map and the coloured dots relate to the type of station.
--------------------------------------------------------------

She then supplies us with a spread sheet, where she gives position and mappping coordinates. I have some small misgivings about some of these positions.

The most important piece of information that I need is how were these points observed and what reference system(s) is(are) in force. Am I correct in assuming that these coordinates are in the Wilkes Pageos system and that heights are relative to mean sea level, (not at all sure of this definition at this moment).

##########################################

Peter,
Do you need further information from me on this?
Unfortunately the results for John's 1993/94 report were lost and since that was before my time at the AAD I have no idea where they went. He does list the coordinates for the GPS base stations used. I have been able to extract results from the AUSLIG/SKM photogrammetry aero triangulation files and the results are attached. John Hyslop would have used the WGS84 datum as he did for all of our work that summer.
In John's 1993/94 survey report he says that aerial photos were taken for geologists in the Snyder Rock's area with reciprocal vertical heights to various stations for a local geoid survey. No mention is made in the report about work for Suzanne Haydon. I suspect that the survey control John surveyed at the time would have been used by Suzanne. Some of the coordinates would be available in ITRF2000@2000 on the Geoscience Australia Geodesy web site.
Regards,
Henk

##########################################

Dear Henk

Thanks for the response.
I have checked your spreadsheet against my spreadsheet and where I know what the station is the tabulated values are the same.
For instance

station 6842.0004 peter is NMS/104 Henk
9330.0020 peter is B052 Henk
But in general it looks like your set and my set are different sets.

The super critical issue are the datum and the level surface. I doubt very much that the datum is WGS84. Most likely it is some system like the Wilkes Pageos expressed in WGS84. We just would not have had access to any precision GPS data at that stage UNLESS the results were processed much later. However I may be very very wrong. The Eastings and Northings for B052 in the Pageos
system are:
479147.034 2648651.160 Pageos System
479156.642 2648908.636 Hyslop
If they are indeed WGS84 then how did they establish this system?

GA's site lists B052 as having IGS2000 coordinates, presumably tied to AUS100 so it's not simple

B052 -66 16 44.6118 110 32 08.4636 20.476 GA ITRF2000
B052 -66 16 43.7304 110 32 08.4588 20.48 Suzanne/Hyslop
B052 -66 16 46.8495 110 32 07.7098 20.0 Wilkes/Pageos Datum

My problem is that I have new data probably in ITRF2000, now some in this Hyslop system, and some in the Wilkes/Pageos and of course lots in the Wilkes Astronomic.

The heights look and have the feel of heights above mean sea level but that is as ambiguous as the universe.

##########################################

Lineage

Progress Code: completed

Statement: The values provided in temporal and spatial coverage are approximate only. AUSLIG is now known as Geoscience Australia. The datum used in collecting these data are not known - it is either WGS84, or Wilkes Pageos.