GPI, Exercise #1. Part 1

Transcription

1 GPI, Exercise #1 In this exercise you will gain some experience with GPI data and the basic reduction steps. Start by reading the three papers related to GPI s commissioning, first- light and observations of Beta Pictoris b. Part 1 In the first part of this exercise, you will install the GPI pipeline and GPI GUI software and work your way through the basic tutorial outlined here: Installing the software consists of unpacking a zip file and setting up a few paths. See Appendix A for the basic steps to hopefully avoid trouble. The tutorial linked above has you work through the very basic steps of reducing data from GPI s commissioning run. The observations are of HD 8049 and its white dwarf companion. White Dwarfs are great commissioning targets because they have smoothly varying, blackbody- like spectra across most of the infrared. Follow and read the tutorial carefully. It is best to read through it first, completely, before doing anything. IMPORTANT: you must change the parameters of the Combine 2D dark images to Method = MEDIAN, by 1. clicking on Combine 2D dark images, under Primitive Name 2. highlight SIGMACLIP, under value, and replace it with MEDIAN (hit enter to save change). sigmaclip tries to run in parallel and, on some machines, it doesn t work. Alternatively (and probably better) is to turn of the parallelization. Edit the file pipeline/config/gpi_pipeline_primitives.xml Search for skip_parallelization and change the default to 1 Or, to turn this off for one reduction at a time, change the parameter value for skip_parallelization from 0 to 1 In the Filter datacube spatially primitive. Also, do not forget to copy the calibration files from the GPI_spectral_tutorial directory that need to go into your calibration directory (this is explained in one of the tutorial steps at the link above).

2 You also need to do the following: cp ~/idl_lib/gpi_pipeline_1.4.0_r4405_source/pipeline/config/pipeline_settings.txt ~/.gpi_pipeline_settings then add the following line (with a tab between at_gemini and 0) to the end of this setting file. at_gemini 0 For part 1, your goal is to extract a spectrum of the WD and compare it to what is shown in Figure. 7 of Macintosh et al (The Gemini Planet Imager: First Light and Commissioning). Plot your results and comment on the differences and their potential causes. Compare your spectrum to those of background and speckles. Experiment with the various options and buttons in the GPITV tool. Part 2 Download H- band data of Beta Pic b from the class webpage and unpack the tar file (tar xvf betapicb.tar) in side of some directory. Start with just a single exposure and make a basic cube as you did for the WD data. Try to locate the planet (don t cheat and look at images on Google). Note: just as in the WD data tutorial above, you will need to make a small manual spot shift for the flexure correction. The shift is very similar, but you might fine tune it a bit. Next try using an ADI / SDI extraction. A good strategy in this case is to use the Data Parser. It will read the data file headers and figure out for you the basic recipes needed for these data. Simply highlight a subset of the files and add them to the data parser. Then you can queue one or more of the recipes it generated. Don t forget to edit the recipe and make the manual spot shift. But, feel free to try it without the shift to see the difference this makes for the planet. Try the ADI with various amounts of data to see how the spectrum and signal- to- noise changes as you add more frames to the sequence. FYI, the ADI processing could take awhile to run for the full set of files. Plot a simple H- band spectrum of Beta Pic b and compare to Chilcote et al Figure 2. Now, comment on potential sources of differences that you see. Feel free to play around with the other options in the pipe to achieve a better reduction! Enjoy J

3 Appendix A Installation notes: You will need access to a machine that has a working IDL version. If you do not have this, come see me. For the discussion below, I will assume you are using a unix- like environment running the bourne- again shell (aka bash). The discussion is similar for other shells (e.g. tcsh, csh, ksh), come see me if you need help translating the steps from bash to your $SHELL Installation instructions for the GPI pipeline and GUIs are located here: However the following should get you through the thick of it. NOTE: If you are already using IDL, I strongly recommend that you create a new directory for installing the pipeline, create a new idl_startup file, etc. this will avoid conflicts so basically pretend you have never used IDL before and have no preexisting startup scripts or libraries. Your UNIX shell needs to know where IDL is located and what to do every time IDL starts up. Add the following lines to the end of your.bash_profile, substituting your name and the correct path to IDL (type which idl to figure this out, or look in /usr/local/bin/ if you are not on a Mac). A1: Edit.bash_profile to include: # # IDL stuff # IDL_DIR=/Applications/exelis/idl export IDL_DIR export IDL_STARTUP=/Users/travis/idl_lib/idl_startup In order for IDL to function in a useful way, it needs to know the location of various routines. This is set by specifying a series of paths to where the routines live on your computer. Now, create a file named idl_startup inside your idl_lib directory, with the following lines (again substituting the correct name and actual path for your system). A2: Create directory ~/idl_lib and make a file called idl_startup inside that contains: device,true_color=24,retain=2,decomposed=0!path='/applications/exelis/idl84/lib:'+!path!path='/applications/exelis/idl84/lib/obsolete:'+!path

4 !PATH='/Users/travis/idl_lib/gpi_pipeline_1.4.0_r4405_source/pipeline/scripts:'+!path A3: Download the latest zip file from here: g- from- zips unpack the contents into your idl_lib folder. You should now have a folder: /Users/travis/idl_lib/gpi_pipeline_1.4.0_r4405_source Now: cd /Users/travis/idl_lib/gpi_pipeline_1.4.0_r4405_source/pipeline/scripts Execute the following script:./gpi- setup- nix Answer yes to the questions. A4: You should now be able to start the pipeline and guis. Open a new window (xterm, terminal, whatever) a new window is important. Type: gpi- pipeline If the all went as planned (and I didn t forget to mention a crucial step), this should launch several windows (with two separate IDL sessions running). At this point you can start the tutorial. Appendix B: Possible issues and possible solutions: Color problems:

5 sudo cp /Applications/exelis/idl84/resource/colors/colors1.tbl /Applications/exelis/idl/ Widget issues see this link: with- xquartz on- macos.html sudo mv /opt/x11/lib/libxt.6.dylib{,.bak} sudo cp /opt/x11/lib{/flat_namespace,}/libxt.6.dylib Make sure source $HOME/.gpienv is in your.bashrc Always launch using shell script gpi- pipeline (this is better).