Changes
/* Change Log */
The Quick Look tool is designed to allow users to quickly assess the quality of their data. It automatically produces simple 1D extractions of science data with a reasonable guess for the target of interest (selectable as either the highest peak or the most central peak in the spatial direction); attempts a sky subtraction using two sidebands (which will also subtract the bias from the raw frame), and produces a 1D extraction.
For arcs, automatic wavelength calibration is attempted. The accuracy of this is appropriate for the spirit of a quick look tool and is typically ~2A. This allows the observer to check that the wavelength range of interest is being covered and to identify spectral features in science spectra. This is not intended to be a final science-quality level reduction and there are a number of caveats on the extraction and calibration process listed below. However, for some users, this may be entirely sufficient for their science needs. Even if it is not precise enough, it can be used as a starting point for a more careful reduction and notes on this are given belowhere https://topswiki.saao.ac.za/index.php/Using_QL_outputs.
<gallery>FullSci.png|Overview of GUI</gallery>
== Change Log ==
'''* 21 December 2016:''' Creation of this page. Initial notes on using the QL GUI, now that the software is stable. Additional details, including videos showing common tasks will be added in the near future.
== Quick Start ==
e.g. if your data are being saved to '''/home/ccd/data/20161212/''', output files will appear in '''/home/ccd/data/20161212/redux/'''
The default files to produce (if the appropriate check boxes have not been unchecked in the QL GUI) are a '''1D ascii file''' and a '''1D extracted FITS spectrum''', a0161390'''a0161390_1D_1D.txt''' and a0161390'''a0161390.ms.fits''' respectively, for an input image named a0161390.fits. Both of these contain the same data, just in a different format depending on the user's preference. Additionally, a log recording the extraction settings used is stored in a0161390'''a0161390.json'''. This last file is probably not of interest to most users.
=== ascii output ===
The ascii spectrum contains the following columns, as labelled in the header:
'''wavelen objCounts skyAndBiasCounts'''
* If the file has been wavelength calibrated, the first column contains the wavelength in A, one line per pixel number. Otherwise the first column will be pixel number (i.e. just running number from 1 to Npixels).
* The second column is the counts in the extraction aperture after sky subtraction (if selected). Note: this is always '''summed counts within the aperture''', even if another extraction option (such as peak counts) is selected.
* The third column contains the '''counts per pixel''' from the sky aperture(s). If sky subtraction has been unselected, these will be 0.
=== 1D FITS file ===
'''Other notes:''' Again, the extraction is only carried out on the individual image (named in the filename). The data has been flipped in x such that the output, extracted spectra run blue to red in increasing x. If comparing with the raw data, keep this in mind.
For using these as the starting point for your '''science-quality reduction''': https://topswiki.saao.ac.za/index.php/Using_QL_outputs
=== .json file ===
The .json file contains a log of the settings of parameters used in the extraction. It may be of interest to users wishing to write their own code for taking these extractions as a starting point, or to users as a double check of which arc was used to wavelength calibrate their data("currArc").
example contents of .json file:
=== Edges of 2D spectrum ===
'''Please don't modify software without discussing and clearing the modification with the software developers or instrument PI.''' To edit the '''bounds of the 2D spectrum''' (cyan lines in 2D plot window) edit as root the following file:
'''/usr/local/etc/qlgui/pars.json'''
The upper and lower bounds of the slit (which can be read off the 2D plot window using the cursor) are given by '''sl0''' and '''sl1''' respectively for the given grating name. e.g. for grating 5, the upper and lower bands are gr5_sl1 and gr5_sl0. Edit the numbers appropriately and resave the file. The changes should take effect the next time a spectrum is loaded.
=== WLC advanced tab ===
In rare cases, the automatic wavelength calibration may fail. The "WLC advanced" tab provides settings to tweak the method used in the fitting. The 2x2 grid of plots on the left show some useful diagnostics of the fitting.
Suggestions for parameter adjustments are given next to the various options on the lower right of the screen. After adjusting any of these, please make sure to reload the current frame on the main tab (not the WLC advanced tab) for the changes to take effect. Note: if the GUI is restarted, these settings will revert to their default values. If you find a set of values which work better than the defaults for an unusual arc/grating angle (or need help adjusting settings), please email "carel AT @saao dot ac dot za" for these to be incorporated into the QL software. The default values should be robust for the most commonly used setups.
