Running the Solar FTS System

Running the Solar FTS System

Power Up

  1. Turn ON the A/D Rack and the FTS Control Rack
  2. Push the RESET button on the FTS Command Unit.
  3. Lock the LASER servo.
    a) Lock the LASER servo on the LASER Control Unit.
    b) Move the Hold/Lock switch on the Laser Control Unit to the LOCK Position
    c) Toggle the PZT Tune until the Square Waves on the O-Scope settle.
    d) Push the RESET button.
    e) Return the Hold/Lock swith to the HOLD position.
  4. Bring up the Oil sytem.
    a) Power ON the FTS Oil System with the FTS Control Panel POWER ON button.
    b) Hold down the white ON button until the green 'lower pressure limit' light goes on.
  5. Enable the Servo Motor on the FTS Control Unit.
    a) Push the 'Sum & Diff' overflow RESET button.
    b) Push the Motor ON button.


Main Menu

	Solar FTS		Main Menu 
	Params	         edit scan parameters
	wlf	         find central fringe
	Go	         begin scanning
	Erase	         erase last scan
	Resume	         continue scanning
	Snap	         take a snapshot scan
	hdr	         edit header file
	Files	         write data & header files
	Util	         utilities

There are two methods of selecting the menu items. To move through the menu from item to item, use the up or down arrow keys. When the desired item is highlighted, hit return and the software will execute the selection. The alternate method of selecting menu items is to type the 1st letter of the menu title. For example, to begin scanning one could use the3 cursor keys to move up or down until the Go was highlighted and press return or one could simply press the letter G.

Parameter Editor

Before one can consider running a scan, the parameter list must be set up. Press P while in the Main Menu and the Scan Parameter Editor will appear.

Click here to see what the Scan Parameter Editor looks like.

Click here to see all the Scan Parameter Definitions.

To change a parameter, use the arrow keys to move to and highlight the parameter to change, type the new value and hit return. Any parameter above the line can be changed. The effect of a change of other values will be seen after pressing return. Press the escape key twice or control-c (ESC ESC or ^c) to return to the Main Menu.


The White Light Fringe routine is used for finding the Central Fringe as well as moving an arbitrary number of fringes. To find the Central Fringe, select the Automatic mode, start with the cateyes in the 'shut down' positions (0 fringes), and check that the number to move is a reasonable 1st guess.

The Manual mode allows some number of fringes entered; then the FTS will move that far by pressing + (forward) or - (Backward). The number cam be entered as an integer (ex. 342000), a floating point (ex. 342000.0), or exponential (ex. 3.42e5).


This selection starts a scanning sequence using the parameters from the parameter list.


This will erase the most recent scan from a coadded sequence. On the EGA monitor, the yellow trace is what will be erased from the coadded interferogram. After erasing a scan, one can stop and store the record on disk (Files command) or Resume coadding scans to the record.


If a scan was stopped to Erase a scan, check the Central Fringe, adjust a light source, or for any other reason, the scan can be continued with the Resume option.


Snap takes a very low resolution, 2-sided scan of the band pass indicated in the parameter menu. The resulting file is then automatically written to Corona's /data3/xx subdirectory.

To plot a transform of the snap, type snap in a gterm or other VT100 emulator that is logged into the /data3/xx directory. Below is an example of a typical snap plot:

Pressing the 'Esc' key will exit the cursor mode & F9 will return to the ASCII window. Type end to exit Gremlin. For more information on cursor options, see the section on "Displaying Data on Corona".


This option brings up the header editor. The header should be brought up to date before the file is written to Corona's disk. The ID, User, Source, etc. information will be saved from the previous file; therefore, it is worth while to carefully set up the first header of a run.

Click here for an example of a typical header.


This is used to write the current scan record to Corona's disk. It will first ask if it's default file name is OK. If it file name needs to be changed from the default, type in the new name at the prompt. If the default is OK, simply hit Return at the prompt.


Util opens up the Utility Menu.

Typical Observing Sequence

  1. GO through the POWER UP & LOGIN procedures.
  2. Mount appropriate detectors & filters on the FTS.
  3. Check that the Alias filter, and the SUM & DIF gains on the Analog filter rack are set properly.
  4. Collimate the light source into the FTS.
    1. Center the light source onto the Collimator mirror as seen through the South Viewing Port.
    2. Adjust the postion of the detectors for maximum output signal.
    3. Select a gain setting for the detectors for an output between 4 - 9 volts.
  5. Find the Central Fringe using the WLF command.
  6. Peak the SUM interferometer's modulation signal.
    1. Plug the unlighted hand paddle into the Sum plug at the bottom of the Oil Rack.
    2. Turn ON the power supply below the plug to ~6 volts.
    3. Switch the meter on the Control Rack to SUM.
    4. Use the hand paddle to maximize the meter's reading.
  7. Balance the modulation of A & B ports.
    1. Connect the O-scope to A-port.
    2. Switch ON the PHASE & DITHER located on the Control Rack.
    3. Center the Central Fringe (the point of maximum modulation) in the O-scope display by using the GO+ and/or GO- buttons found on the Command Unit.
    4. Adjust the O-scop gain so that the Central Fringe peak-to-peak modulation is full scale on the display:
    5. Unplug A-port from the O-scope and plug in B-port.
    6. Adjust the B-CHANNEL ADJUST knob on the Analog Rack so that the B-port modulation has the same amplitude as A-port:
    7. Turn OFF PHASE & DITHER control.
  8. Fill in the nessesary Header information. To enter the Header Editor, type H in the Main Menu.
  9. Go to the Parameter Editor (type P at the Main Menu) and change the parameters as needed.
  10. Do a "Snap Shot" scan to verify the parameters and setup.
    1. Type S in the Main Menu and wait until the scan is complete (the Main Menu will reappear).
    2. Move the arrow into the GTERM window and type snap. An FFT will be performed and a plot of the spectra will appear.
    3. Hit the esc key then F9 to exit the plot. Type end to return to the UNIX cursor.
  11. Verify that the system is still at the Central Fringe.
    1. Display A-port on the O-scope.
    2. Switch ON PHASE & DITHER.
    3. Check that the Central Fringe still looks as it did in step 6.
      If not, use GO+ and/or GO- to recover.
    4. Turn OFF PHASE & DITHER.
  12. Go back to the Main Menu and type G to start a scan.
  13. When the scan is complete (the Main Menu will reappear), check the Central Fringe (see step 11).
    If the Central Fringe doesn't look like it did before, the scan must be repeated (return to step 12).
  14. Write the data to Corona's disk drive (option F in the Main Menu).
    Be sure that the file name is what is wanted.
  15. Update the Header for the next scan (see step 8), and start the next scan (step 12).

Transforming Data on Corona

Move to a gterm window on Corona and change to the directory the interferogram to be transformed is in (normally /data3/xx). Make sure all the information in the header is correct.

      :     FTS Interferogram Transform Program     :
      :    4M Gemini Gremlin 0.99 of 10 Jun 1993    :
      :         National Solar Observatoy           :
      :               James W. Brault               :
	   Date:   93.10. 6      Time:   10:19:15

10:19:16   alias s? "whats saved"
Alias no.   1 entered
10:19:16    alias readarc "option readarc"
Alias no.   2 entered
10:19:16    keyboard
[~]: greg FILENAME
processing FILENAME
To exit Gremlin:

Displaying Data on Corona

FTS spectral data can be examined using one of two software packages, Gremlin and isaac. Isaac runs under IRAF and has its own User's Manual. Gremlim is the package that is used all for the examples here.

Using Gremlin to look at Transformed Data

[^]: open datain FILENAMEr
[^]: read [^]: plot Shown here are some useful commands for manipulating data in Gremlin:

[^]: s?                <- what's in the scratch files
[^]: save 5 'stuff'    <- save current data set in scratch file 5 & named 
                          stuff (scratch files 1 - 16 can be used)
[^]: recall 5          <- read scratch file 5 to 'r'
[^]: recall 4 tr       <- read scratch file 4 to 'tr'
[^]: exchange          <- swap 'r' & 'tr'
[^]: combine 1. 1.     <- sum of 'r' & 'tr' stored in 'r'
[^]: combine 1. -1.    <- difference of 'r' & 'tr' stored in 'r'
[^]: ratio             <- ratio of 'r' & 'tr' stored in 'r'
[^]: help              <- display a list of available commands or a 
                          description of the command follow help.

Writing a Tape

{/data3/xx:10 cd
Return to the login directory from a GTERM window.
{/data3/xx :11} cl
cl > nso
ns > fts
Log into the IRAF Command Language & move to the fts directory.

Before taping the fts files (interferograms & spectra) must be converted from FTS Type6 header formats to IRAF Image Files.
ft > read6
Reads FTS Type6 and writes an IRAF Image File.
Input file template (oldfiles.*): filename.*
The filename can use wild cards and operate on several files.
Output image root name (wcl.1093.real): nameout.
A number will be added to the output filename, .001, etc.
The prompt returns when it's done.

Load an ExaByte tape into the tape drive and allocate the drive.
ft > allocate mtalo
Write the files onto the tape in FITS format.
ft > wfits nameout.* . . .
ft> rewind mtalo
ft> deallocate mtalo
Remove the drive's tape by pushing the botton on drive's front.
ft> logout
Exit IRAF.

Reading a Tape

Log into the IRAF Command Language as above (Writing a Tape).
{/data3/xx :11} cl
cl > nso
ns > fts
ft> allocate mtalo
Load and allocate the tape drive.
ft > rfits FITSnamein
rfits will read the FITS files on the ExaByte and write IRAF image files onto disk at the current directory with a serial number appended to the individual filenames.
ft> rewind mtalo
ft> deallocate mtalo
Remove the tape from the drive by pushing the button on the drive's front.
ft> logout
Exit IRAF.
Enter GREMLIN (see Transforming Data on Corona).
{/data3/xx :5} gremlin
[~]: create Filename
This is the output Type6 filename & will include a .hdr & .dat extension.
[~]: copy fits FITSnamein
This is the input FITS Disk Format Filename.
[~]: close dataout
[~]: close datain
[~]: end
Exit GREMLIN or see the section on Displaying Data on Corona

Power Down

  1. log out of DosEquis.
    1. Type 'u' to get into the Utilities Menu.
    2. Select the exit ('e') option.
    3. Type ~. to disconnect DosEquis from Corona.
  2. Exit SunView.
    1. Move the mouse to the background (the solid color between the windows).
    2. Push & hold the left mouse key.
    3. Move the mouse to the Exit SunView option in the menu that appears.
    4. Release the mouse key.
  3. Put the Catseyes into 'shut down'.
    1. Power OFF the Servo Motor.
    2. Wait until the Sum & Difference square waves settle down on the O-scope display.
  4. Turn OFF the power to the FTS Oil Rack.
    1. Wait for the oil pressure gauge on the side of the FTS tank to fall to ZERO.
  5. Switch OFF the A/D & FTS Control Racks.
  6. Give Babar a pat and say "goodnight"...