The first reduction step consists of indexing the echelle order boundaries.  This is done using a flat field exposure.  Using the browser, select a single internal quartz lamp spectrum from your run and then click "Trace Orders."  The software will run for 15-20 seconds and then present an atv window showing the flat field image with order boundaries marked in either black or another color, depending on your display settings. 

Browse around the image for a bit to make sure that the fit to the edges makes sense everywhere.  About 1 out of 10 times, the fit is bad in the upper left corner of the array.  If you find this condition, try another exposure - this usually works.  Or, if you select multiple exposures the software will average them together and fit on the combined image.

You will know that the software worked correctly if: the slit boundaries are located correctly on the image, and a file is produced in the subdirectory redux/Flat with the name "Orders_0123.fits" where 0123 is the frame number of whatever file you used to trace the slits.

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6 Comments

  1. Unknown User (fbauer_1@touchstonenetwork.net)

    nevermind. oddly seems to work now.

    1. Unknown User (fbauer_1@touchstonenetwork.net)

      Ok, having the problem again when I redo from scratch. Basically, for flats I took with 0.60", Echelle mode and 1.2e-, I was getting a consistent failure because the fire_traceorders.pro was finding a different number of edges for the left and right. I changed the initial y1 and y2 values to 

      if (n_elements(y1) EQ 0) then y1 = 1240.0
      if (n_elements(y2) EQ 0) then y2 = 1250.0

      from

      ;if (n_elements(y1) EQ 0) then y1 = 1250.0
      ;if (n_elements(y2) EQ 0) then y2 = 1260.0

      And everything worked out. The original y1 and y2 values worked for all my other slit width and gain configurations. *shrug*

  2. Unknown User (enewton_1@touchstonenetwork.net)

    deleted

     

  3. Unknown User (phil.massey_1@touchstonenetwork.net)

    deleted.

  4. Unknown User (phil.massey_1@touchstonenetwork.net)

    On some echelle data obtained in early February 2017 with the 0.6" I was unable to get the "trace" to work despite the usual fiddling: it could find the left edges but not the right edges.  I found that setting "use_pre_stored_edges = 1" in fire_traeorders worked well; the pre-defined values  YMMV, of course.

     

    Oddly, talking to other recent observers, no one seems to have been successful in getting the "trace" to work even on well exposed flat fields.  Often in the past i've found that it it will work on some flats but not on others, but this time no individual flats (either flats or skies) worked.  

    1. Robert A Simcoe

      Hi Phil - can you contact me offline and send an example frame?  I'd like to see what is going on if this is widespread.  We took data a week ago that seemed to find the trace OK, but I should see how it differs (if at all) from ours and also whether our pipeline versions are the same.  Thanks -R