Table of Contents
Geodetic Post-processing
Geodetic observations require different post-processing to that of astronomy observations. The data is required to be submitted in a particular format. The Haystack Observatory Postprocessing System (HOPS) software is used for this purpose.
Setting Environment Variables
source ~/corr_test.setup
This contains the geodetic environment variables:
export HOPS_STATION_CODE=/nfs/apps/vlbi/lba_locations/hops_station_code.txt
export DEF_CONTROL=/nfs/apps/vlbi/lba_locations/fourfit_control.txt
export PATH=${PATH}:/nfs/apps/vlbi/hops/x86_64-3.8/bin
export HOPS_QUIET='SHH'
. ~/bin/hops.bash
The following variables also need to be defined:
export CORDATA=/Exps/exp_name/ export DATADIR=/Exps/exp_name/
where an example is:
export CORDATA=/data/corr/corrdat/p483a
fourfit
From correlation the data need to be in the mark4 format:
difx2mark4
To run fourfit:
fourfit -txa 1234
This gives a set of plots to inspect.
To rerun fourfit:
fourfit -a 1234
aedit
Creating the files required by aedit
The input data file for aedit is alist.out . This is created by the following command:
alist *
The experiment names (16383) need to be modified in this file to 1234.
Aedit also requires an .ovex file for input, not a .vex. This is generated from a perl script:
./nskd_ovex.pl p483a.01.skd >> 1234.ovex
Changes have been made to the perl script when reading in the source name as it was not pulling in the data correctly.
The .ovex file now contains data with 1-letter code station IDs (mk4_site_ID). These may be incorrect and need to be checked manually. This step will be incorporated into the nskd_ovex.pl code itself soon.
The complete list of Mark4 Station Codes
Station codes:
| Station | 2-letter code | 1-letter code |
|---|---|---|
| Hobart26 | Ho | H |
| Hobart12 | тАУ | - |
| KATH12M | тАУ | - |
| YARRA12 | тАУ | - |
| WARK12M | Ww | W |
| HART15M | Ht | g |
| PARKES | Pa | e |
Put this file, 1234.ovex, in the 1234/ directory.
Running aedit
aedit allows the user to flag the baselines that have bad data.
To start aedit, reading in an input list:
aedit -f alist.out
Remove duplicate data based on SNR (or other parameters)
edit dup SNR
Print to screen a summary of the data:
sum 2
Choose parameters to use:
parameter 1 2 6 7
Write pcal to file:
pwrite pcal.txt
To sort, and only use data of certain quality:
gcodes 1-9 sort baseline sort freq edit input
To plot the data:
psplot
This is where data can be flagged as bad and removed from the data set.
