Creating zoomed figures using APLpy

Hi everybody!

I started to work with APLpy lately to slice my data cubes into 2D plots. So nice and wonderful! But - like always - I stumbled upon an issue... The argument slices the Z dimension of the cube. I also want to control where my axes X and Y begin and finish.

In the example below, I'll show how I solved this problem:

import matplotlib
matplotlib.use('Agg')
import aplpy

# to slice the data cube at Z = 47:
img = aplpy.FITSFigure('figure.fits', dimensions=[0, 1], slices=[47])

# show the image in the canvas:
img.show_grayscale()

# to get the limits of X and Y coordinates:
img._ax1.get_xlim()
# (0,100) --> APLpy will return this limits, here in pixels for instance 
img._ax1.get_ylim()
# (0, 200) 

# now, to set the limits of X and Y:
img._ax1.set_xlim(25, 75) # like a zoom in your plot
img.show_grayscale() # don't forget to refreshyour plot!
img._ax1.set_ylim(50, 150) # 100 to the left, 100 to the right, in pixel
img.show_grayscale()

I found that's simply like to create a subplot. That's worked for me! :)

HDMGETR: No value found

Edit file:

$ sudo vim /iraf/iraf/noao/imred/ccdred/ccddb/kpno/camera.dat

-1		exptime otime
	+1	exptime exptime

A maldita libstdc++5

Depois de tanto procurar toda vez que precisava instalar essa maldita biblioteca, eu finalmente encontrei o site oficial e resolvi postar. Tá aqui!

http://packages.debian.org/stable/base/libstdc++5

Issues installing Pyraf

Let's make this very short. Before you try install PyRAF on your Linux machine, be sure that you have installed:

• IRAF
• Python
• Scipy
• Numpy
• Matplotlib
• PyFits
• python-pydev
• xorg-dev

This should do and you shall have any problems with it. 

"Improved 3D Fabry-Perot Data Reduction Techniques" Solved

In this post, we followed the steps described in this site to install a package that reduce 3D data obtained with Fabry-Pérot. We ended with an error regarding to the step number 7, where the 'build_baryc' procedure failed to run.

The solution to this problem envolves basically two steps. The first one, no matter where you start your IDL, it will look for the 'baryc.c' file at your home directory. At least, that happened to me. So, to be sure where you are, once you start IDL, type '$pwd' to know the directory that you are or '$ls baryc.c' to be sure that you have this file in the current folder. If you realize that you are in the wrong place, just type 'cd, "/my/path/to/the/FPreduc"' and, then, try to run 'build_baryc' again.

The second problem that may raise is related to the compiler gcc in Ubuntu. It is a particular problem that seems to happen only in this plattaform (we don't know about the other Unix distributions). According to the author, the error is raised by a stack smash protection that could be enabled by default on Ubuntu. This can be solved by modifying the 'build_baryc.pro' by adding the following line:

cflags='-fno-stack-protector -fno-stack-protector-all'

just before the 'MAKE_DLL' procedure is called. In my case, gcc did not recognized the second flag, so I kept only the first one.

After all of this, just follow the rest of the guideline in the instalation procedures and it will run perfectly.

"Improved 3D Fabry-Perot Data Reduction Techniques" Instalation problems

Ok. From a long time I have been trying to install this package used to do data reduction in astronomical cubes of data. Today, I will follow every step with a lot of attention so I can be sure that I am not doing anything wrong.

------------------------------------------------------------------
1. Install the IDL astrolib library

From the other times that I tried to install FPDRT on my machine, I got a folder from a friend which has the astrolib. This time, I downloaded it from the website. Since my machine is a Ubuntu 10.04 (Unix System), I downloaded the astron.dir.tar.gz. This file seems to be more organized that the other one available for Unix, that's why I choosed it.

Since I have a lot of trash in my lib folder already from other attemps, I created a astrolib folder in my idl folder and unzipped the astro file inside it. After that I added this folder to my IDL PATH variable at the idl_startup.pro. Then, I runned IDL and typed AIRTOVAC to check.

------------------------------------------------------------------
2. Make sure the IDL astrolib library is into your IDL path.

Well... it is. I did this already in the last step.

------------------------------------------------------------------
3. Download the package 3d data reduction package (latest version: 5.03).

Nothing special here.

-----------------------------------------------------------------
4. Uncompress the 3d reduction package into your favorite directory.

Here, I did it into the idl folder. I created a FPreduc directory inside it and uncompressed the files inside it. Only to prevent any error, I gave all premissions to this folder and to the astrolib folder.

------------------------------------------------------------------
5. Add this directory to your !path variable (can be done through the IDL_STARTUP script)

Ok.

------------------------------------------------------------------
6. Go into this directory and start idl.

Ok. Only to be sure...

% pwd
> /home/myhome/.idl/idl/fpreduc
% ls
> FPreduc

------------------------------------------------------------------
7. At the idl prompt, type « build_baryc ». This will compile and install the baryc C submodule.

Then... the error:

IDL> build_baryc
% Compiled module: BUILD_BARYC.
% MAKE_DLL: Writing build script: /home/bquint/.idl/itt/compile_dir-118-

-linux-x86-m32-f64/baryc_10121_salamander.sh
% MAKE_DLL: Writing linker export file: /home/bquint/.idl/itt/compile_dir-118-idl_7_0-linux-x86-m32-f64/baryc_10121_salamander.export
% MAKE_DLL: Running build script: /home/bquint/.idl/itt/compile_dir-118-idl_7_0-linux-x86-m32-f64/baryc_10121_salamander.sh
% gcc -fPIC -I"/home/bquint/.idl/idl70/external/include" -c -m32 -D_REENTRANT "/home/bquint/.idl/idl70/fpreduc/baryc.c" -o "baryc_10121_salamander.o"
gcc: /home/bquint/.idl/idl70/fpreduc/baryc.c: Arquivo ou diretório não encontrado
gcc: no input files
% FILE_COPY: Unable to obtain file status. File: baryc.dlm.orig
No such file or directory
% Execution halted at: BUILD_BARYC 17
/home/bquint/.idl/idl70/fpreduc/FPreduc/build_baryc.pro

% $MAIN$

Trying again inside FPreduc folder... 

~/.idl/idl/fpreduc/FPreduc$ idl
Version 7.0 (linux x86 m32). (c) 2007, ITT Visual Information Solutions
loadable module definition file lacks a MODULE directive:
/bquint/.idl/idl70/fpreduc/FPreduc/._baryc.dlm.

... in the end. #fail

IDL Startup Pro

I want to run a .pro file when opening my IDL. To do that, first I have to create a file name idl_startup.pro. I can write any IDL script thing there. Like:

print, "Hello!"

Then, one has to append the folowing lines in .bashrc.

IDL_STARTUP="/my/path/to/idlstartup.pro"

export IDL_STARTUP

After that, simply run IDL.