IMACS data reduction at LCO
On this page we are collecting information on various tools available
for reducing all kinds of IMACS data. For all instruments you will find
all the relevant documents on the observer workstation data disks in
each dome, under Backup/Calibrations_and_Tools/Documents/
We are also storing calibration frames for comparison, (or building master fringe frames, etc.) at Backup/Calibrations_and_Tools/IMACS/
For users wishing to write their own reduction, the chip offsets for the f/2 and f/4 mosaic cameras may be helpful. These are taken from the “Dewar Definition” files of Cosmos2 and provide the relative offset of each chip with respect to each other. The following graphic illustrates the layout of the chips as they appear in the IMACS QuickLook GUI. Note that the output of the IRAF imosaic task is inverted in y.
Tools available at LCO
- Cosmos2 is a package (by A. Oemler, Carnegie and supported by D. Kelson, Carnegie) for reducing multislit, long-slit or MOE data. A mini-cookbook is available on the observer workstations to help beginners work through the data reduction. This is best used in conjunction with the documentation on the Cosmos website, but provides a quick reference when working “online” on a dataset at the telescope.
- Photpipe (TBA) – Armin Rest’s mosaic camera image data redcution and photometry pipeline.
- KungIFU is an IFU data reduction package by Adam Bolton (now at IFA, Hawaii). This is currently only operating for f/4 data, but we are working on a fix for f/2.
In addition, you will find on the workstation data disks some quick-look cookbooks to help you run through an IMACS imaging or long-slit dataset using standard IRAF tools.
Using Cosmos at LCO
The observer workstations are installed with up-to-date versions of the Cosmos package. To initialise a Cosmos session, change directory to where your data is located in an xterm or Terminal, and type “Cosmos2” on the command line. You will also need an IRAF window open if you wish to display your spectra and the predicted line positions for interaction. A quick-reference cookbook listing all the steps required to reduce multislit and long slit data is available on the datadisks on each workstation at /Volumes/Data_<HOSTNAME>/Backup/Calibrations_and_Tools/IMACS/
First time users should use this resource in concert with the full cookbook and the individual program descriptions available on the Cosmos website.
Using KungIFU at LCO
Using IRAF tools to reduce IMACS imaging
ccdproc can be used on each individual chip in the standard way. Scripts to do this are available on the observer workstations datadisks in the dome. We have a couple of useful stitching tools, igapmos (in the IRAF imacs package) and imacs_wcs.py (available on the standard macosx command line) to help stitch the reduced chips together in the right order. These tools use the information in the headers to produce an approximate linear WCS. This can then be refined by comparing the image to an astrometric list. The tool iwcs (in the IRAF imacs package) can be used for this purpose.