Print, ypos ypos at given wavelength and fiber 1313įirst read in the 'FLUX' and 'WAVE' (wavelength) extensions with MRDFITS. Print, xpos xpos at given wavelength and fiber 1313 Print, wave wavelength chosen for position of fiber Ypos = MRDFITS(file,"ypos") reading in the ypos Xpos = MRDFITS(file,"xpos") reading in the xpos Let's read in xpos and ypos and find out the location of fiber 1313. Usually you can take the position at a single wavelength, say at Hα (6560 Angstrom) or 5000 Angstrom, depending on what wavelength range is interesting for your science. The positions can change slightly as a function of wavelength cause of the different dispersions. These positions are also in a 2D array of wavelength and fiber.
![idl size idl size](https://www.l3harrisgeospatial.com/Portals/0/blogs/imageryspeaks/JoePeters/_1_Code.png)
These give the position in arcsecs along the x and y axis, with the center at the orgin (0,0). To find the location or position of the fiber in the IFU, we use the xpos and ypos extensions. Find the location of an individual fiber in RSS The Hα emission line is the strong line towards the center and emission lines are on either side. We can now replot the flux in this wavelength range. Hα emission is at 6560 Angstroms in the rest frame. Restwave = wave/(1.+0.04) rest frame wavelength First, we should correct for the redshift. Now let's zoom in to look at the Hα emission. The error should be very small and close to zero, with some spikes around the emission lines. We can also use ivar to overplot the one sigma error for this fiber spectrum. The overplotted green spectrum should be almost identical to the original spectrum. Ok = WHERE(mask(*,1313) eq 0 and ivar(*,1313) gt 0) finding good pixels Besides the mask, whenever ivar is 0, this also indicates a bad pixel. Now we can overplot the flux of fiber 1313, masking out any bad pixels. When mask does not equal 0, this indicates a bad pixel. Both are the same size and format as the flux extension. The mask and ivar extension are also useful.
![idl size idl size](https://m.media-amazon.com/images/I/71fWRnuztxL._SL1500_.jpg)
You should see a nice emission line spectrum, with the strongest line being Hα around 6850 Angstroms (note it is not at 6563 Ang due to the redshift of the galaxy). Plot, wave, flux(*,1313), /xs, xtitle='wavelength(Ang)', ytitle='Flux' We will choose fiber 1313 because it is located near the center (finding fiber positions will be discussed later). Now, let's plot a spectrum for a single fiber. Plot a spectrum from a single fiber in RSS Print, size_rss(1) number of wavelength pixels The flux has dimensions of wavelength vs number of fibers, where the number of fibers is the IFU size times the number of exposures (127x15=1905). Wave = MRDFITS(file, "wave", hdr4) wavelength in AngstromĪs the flux and wavelength was read in, IDL should have printed the size "MRDFITS: Image array (4563,1905) Type=Real*4" for flux and "MAURITIUS: Image array (4563) Type=Real*8". Note that the extensions for the MaNGA RSS files are listed in its datamodel.įlux = MRDFITS(file, "flux", hdr1) flux in 10^17 erg/s/cm^2/Ang/fiber In your IDL terminal, read in the flux and wavelength extensions. The differences between the RSS and datacube files are here. Examples of plotting and exploring spectra are included.
Idl size how to#
This tutorial will first describe how to access RSS files with IDL, and then continue with a description on how to access datacubes.
Idl size download#
You can download the RSS file and datacube for this galaxy yourself with the following rsync commands in your terminal (replace LOCAL_PATH): RSS