fspecred.pro --- Spectral data reduction pre-processor for FOCAS spectra

• What this task dose:
  • Distortion calibration
    • object, CAL 共にまったく同じ補正を行なう。
  • Flat Fielding
    • Flexure による slit pattern のシフトをキャンセルため、CCD固有のパターンとスリットパターンを分離する。
    • CAL と dome flat の slit pattern を比較することで、シフト量を自動的に計算する。
  • Cosmic-ray removal
  • Bias subtraction (option)
  • Grism rotation correction (option)
    • Grism alignment error を補正し、分散方向が CCD の Y 方向になるようにする。
      • Long slit のギャップを自動とレースし、ギャップが Y 方向にまっすぐになるように菱形変換を行う。
      • 観測中に万が一 grism rotation 角度が動いてしまう場合を考慮し、CAL, Object 別々に gap trace を行って、それぞの補正で菱形変換を行う。
      • MOS mode では使えない。
  • Procedure summary diagram
• Input data:
  • Object.fits
  • Flat.fits
  • CAL.fits (Comparison lamp image)
  • Bias.fits
• Output data:
  • Flat fielded, distortion-calibrated Object.fits
  • Distortion-calibrated CAL.fits
• Usage

  fspecred.pro start-up

  Input file names

1. Input files (Flat.fits, Cal.fits, Object.fits, Bias.fits

• Set number of bias images for multiple bias files

1. Output files (Object_Reduced.fits)
2. Mosaicing/Distortion data files

• Ask FOCAS people for the current best parameter file

Check if you want to do grism rotation

• In case of MOS spectra, do NOT use this option.

Check if you want to set observed region using Mouse

1. In case of mouse selection
   Click the image two times; first in lower-left corner, and next in upper-right corner
2. In case of NO mouse selection
   Input lower-left and upper-right pixel coordinates of your interest region.

Sky subtraction

Note: Sky subtraction is just for cosmic removal.
You must do the sky subtraction after this procedure

Select sky regions by MOUSE

Click two times on the left side of the object (from left to right)
Then, click two more times at the reft side of the object (from left to right)

Like this:

[      SKY         ][OBJ][      SKY        ]

                     /\
                    /  \
-------------------/    \-----------------
#1              #2       #3             #4
Click four times at #? position

Cosmic-ray removal

The cosmic-ray removal is automatic.
An iterative median filtering is applied. The median parameter is pre-defined for FOCAS data.