NIRC2 Reduction Workshop (Use both sides)

1) EXAMINING THE FILES

a) Goto your ImagingData/Calib directory.  In an imaging viewer open a flatfield image from the "domeflat.list".  What are some of the features that you see in this image?




b) In the same directory open a file from the domedark.list.  How is this file different?




c) Open  a dark10x10 image.  What are the features in this image?




d) What does a dark150 image look like?  Why do you think that these images behave this way?




e) Goto ImagingData/Object1.  Examine a goods68 file.  These are science images of galaxies in GOODS-S.  What do these images remind you of?  Why?




f) In idl or iraf subtract one goods68 image from another and examine the difference image.  What does the difference look like?




g) Compare an M50 image (open cluster) to an fs12 (standard star) image.  What are the differences in the light profiles of the stars? (You can try imexam in iraf, or the atv profile tool in idl for this).  Any theories on why the light profiles of the stars in these two images are different from each other?




2) IMAGE REDUCTIONS

a) Use the jred_reduce.pro program to reduce the goods68.list.  The program can be found in the nirc2_reduce/templates directory of the idl code.  Make a copy of the file with a new name (i.e. jred_goods68.pro).   Place the copy in the nirc2_reduce directory.  Edit the program so that it will find the goods68.list of images.  Also make sure to change the name of the program inside the idl code (first line of the code) to match the name you gave the file.  As the reduction is running, examine the j_reduce.pro idl program. This program is doing all of the work.  Try to figure out and write down the different steps it is working on.  These steps will be summarized in a printout at the end of the program.  Do you understand what it is doing?  Are there things that you might do differently?







b) Examine the final images produced by the program including the sky images, flat images, reductions of the individual frames (in the "reduced" subdirectory), and the final combined image.  What do you think of the reduction?  Reduce the M50 data as well.  We may use these images in the PSF discussion following this part of the workshop.







c) In the Object2 directory, run the jred reduction routine on the kkh98 (Dwarf irregular galaxy)  list and the kkh98short list.  Examine the reduced individual fames.  Are there any images you might want to cull from the list?  What kind of culling strategy might you choose?  How would you tell if the resulting image is an improvement over the full data set?  Try to produce a improved image through culling.