Updated url to relevant astropy data file

Author: eblur

tutorials/notebooks/synthetic-images/synthetic-images.ipynb

@@ -79,12 +79,12 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
-    "file_i = download_file('http://www.astro.wisc.edu/~ychen/MHD_Jet/fits_dtau_005c/synchrotron_i_lobe_0700_150MHz.fits', )\n",
+    "file_i = download_file(\n",
+    "    'https://astropy.stsci.edu/data/tutorials/synthetic-images/synchrotron_i_lobe_0700_150MHz.fits', \n",
+    "    cache=True)\n",
     "hdulist = fits.open(file_i)\n",
     "hdulist.info()\n",
     "\n",
@@ -102,9 +102,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "print(hdu.data.max())\n",
@@ -122,9 +120,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "fig = plt.figure(figsize=(6,12))\n",
@@ -170,9 +166,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "cdelt1 = ((hdu.header['CDELT1']*u.cm/dist_obj.to('cm'))*u.rad).to('deg')\n",
@@ -241,7 +235,6 @@
    "cell_type": "code",
    "execution_count": null,
    "metadata": {
-    "collapsed": true,
     "scrolled": true
    },
    "outputs": [],
@@ -252,9 +245,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "wcs = WCS(hdu.header)\n",
@@ -307,9 +298,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "# By default, the Gaussian kernel will go to 4 sigma\n",
@@ -337,9 +326,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "# set FWHM and psf grid\n",
@@ -411,9 +398,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "wcs = WCS(hdu.header)\n",
@@ -435,9 +420,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "file_q = download_file('http://www.astro.wisc.edu/~ychen/MHD_Jet/fits_dtau_005c/synchrotron_q_lobe_0700_150MHz.fits', )\n",