UNDERGRADUATE ALFALFA TEAM
Below are the detail steps to create contour maps of the HI sources, the overlays with an optical image, and the programs needed. Each program links to the header of the program and some extended explanation for each of them.
1. From the sources in your catalogue that you want to create contour maps for, identify the velocity and channel range, the RA and DEC, the pixel coordinates and the main channel of each galaxy.
2. Use slice_it_test.pro (in IDL) to plot the contours for 16 channels around the center channel of your source. With this program you can get a general idea of what the contours look like. This is only useful for you to see what contours exist in more than 3 channels.
SLICE_IT_TEST, datacube, channel_center, channel_boxcar, channel_increment, level_scale, pos_x, pos_y, pos_size, postscript
3. Use box_it.pro (in IDL) to box what you have selected in your 4x4. This program makes contour plots for specified channels in a grid datacube and allows for the user to box and write the "good" data to a new array.
BOX_IT, datacube, channel_start, channel_range, channel_boxcar, level_scale
4. Use read_it.pro to create contours. This program takes the "good" data selected by the program box_it, and sums it up into one contour.
Read_it, filename, OPTION
read_it, "box_it_data.sav", 0
You will need to restore the grid before using the program.
5. Use the getcoords.pro to box the contours that you want to use to create overlays. This program gives the size of the box you create around the contours and the center coordinate of that box. From that, find the corner coordinates of the box because you will need both the coordinates of the center and the corner of the box to create an overlay.
6. Use the center coordinate and the box size to create the image using the program mosaic in the pagehttp://hachi.ipac.caltech.edu:8080/montage/ . You should use the SDSS R band and use the best resolution possible (0.4 arcsec)
7. In Unix, once the image is done (this could take a long time) use the command wget and then the link to the fits file to download the image. Check that the image is the right one before downloading.
8. In IDL, use the command img=mrdfits('mosaic.fits') to convert the file into a .sav file. The mosaic.fits is the name of the file that you downloaded.
9. In IDL, use the command save,img,filename='img.sav' to save the file as .sav file.
10. In Unix, change the name of your mosaic.fits to a specificname.fits
This step is optional. But I recommend it in case you need to reuse the image.
11. In IDL use overlay.pro to create the final overlay. To save the image take a screenshot of it.
Name the same type of files in the same way.
EX. For Box_it: box3.sav
Make sure to know what the names correspond to.
Have a spreadsheet where you keep track of all the information and the steps that you have done for each image.
Always check the programs and compile any changes. The programs are well commented so read them, they are really helpful!
Ana Paola Mikler, Union College
Nicholas Crump, George Mason University