Command-Line Program

QuickSpecSim

This package includes a command-line program quickspecsim that simulates a single spectrum and saves the results as a FITS file and/or plot. To see the available command-line options use:

quickspecsim --help

The --config parameter specifies the top-level configuration file to use and defaults to test. Without any arguments, the program simulates a constant flux density source using the test atmosphere and instrument models, producing the output:

Median SNR in b camera = 1.165 / 0.5 Angstrom
Median SNR in r camera = 0.941 / 0.5 Angstrom
Median SNR in z camera = 0.742 / 0.5 Angstrom

Use the --output option to save the simulation results to a FITS file with the following structure (as reported by fitsinfo):

No.    Name         Type      Cards   Dimensions   Format
0    PRIMARY     PrimaryHDU       5   ()
1    SIMULATED   BinTableHDU     45   63001R x 18C   [D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D, D]
2    B           BinTableHDU     29   4760R x 10C   [D, D, D, D, D, D, D, D, D, D]
3    R           BinTableHDU     29   4232R x 10C   [D, D, D, D, D, D, D, D, D, D]
4    Z           BinTableHDU     29   4798R x 10C   [D, D, D, D, D, D, D, D, D, D]

Use the -save-plot option to visualize the simulation results, for example:

quickspecsim -c desi --save-plot sim.png

produces the following plot of a simulated 22nd AB magnitude reference source:

Simulated DESI response

A limited number of simulation parameters can be changed from the command line, such as the exposure time, airmass and source magnitude. For more substantial changes to the simulation models, copy and edit an existing configuration file.

QuickFiberLoss

The quickfiberloss command-line program is primarily for performing speed benchmarks of fiber acceptance fraction calculations using GalSim, which are usually the rate-limiting step when these calculations are performed on the fly. To see the available command-line options use:

quickfiberloss --help

The --config option has the same meaning as above, but only the instrument section of the configuration data will be used. Normal usage is, for example:

quickfiberloss -n 100 --disk-fraction 0.5 --bulge-fraction 0.5
Elapsed for 100 targets = 58.286 s, Rate = 582.861 ms/target

To measure the speed up for disk-only galaxies, try:

quickfiberloss -n 100 --disk-fraction 1.0 --bulge-fraction 0.0
Elapsed for 100 targets = 1.708 s, Rate = 17.084 ms/target