Data Analysis

An outline procedure for reducing your data

 During your run you can do quick-look reductions on individual runs to check the data
quality, the approximate seeing, etc.

 To reduce your data:
1. Transfer the data to algorab or wait for it to be transferred during the regular back-up
2. Login to algorab as snert.
3. cd /import/chef2/susi/analysis (or cd susi/analysis, its the same thing)
4. Create a directory for the nights data. Note the dir pattern: analysis|HR#|bline_length|date
5. cd into this directory. Do 'css yymmdd', yymmdd = date of data collection. Creates a reduction
    script for that date.
6. Emacs check_v2_yymmdd.script, where yymmdd is now the date when the script was created.
7. In emacs menu: IDLWAVE|External|Start IDL shell. Click in window containing check_v2...
8. Debug|Compile &run|save and .RUN

Wobble Chopping
Before about 050711 a single large wobble file (*.wob) was recorded for all data for each source
observed each night. These required 'chopping'. From 050117 the scheduler started separate
wobble files (*.wob2) files for each fringe file.

'Chopping' of .wob files was done by MJI in one hit in about late 2005. But it didn't always work.
Some .wob2 files are chopped in the wrong place leading to errors like,
 "Warning! Wobble does not cover the fringe data period.
 Accuracy of    40.34534seconds of wobbler lock not verified."

To fix this, do:
 -chmod u+w the data directory 
 -log in as susi and cd into the data directory
 -save the old .wob2 files to oldwobs/, say.
 -cp ~susi/code/analysis/  to .
 -start idl, then, eg. do:
 -IDL> chop_wobble, ['01_2550','02_1922','03_2020','04_1922'],'01.wob',fixed_offset=5
  Find the value of fixed_offset by trial and error, continuing until the pipeline no
  longer reports the above error. It may be necessary to chop out individual .wob2s
  with different fixed_offsets?
 -Delete, oldwobs/. But keep the original .wob file!
 -Maybe add a README file to explain what you did.
 -chmod u-w * to protect all the files
 -cd .. and chmod u-w the data diretory you were modifying.

Note: the above error can also occur if the wobble file was started late, ie. if there really is
 missing wobble data. It is possible to detect the difference but I dont have time right now to 
 explain how, Ask me! APJ 070306.

Andrew Jacob
Last modified: Fri May 28 14:27:13 EST 2004