diff --git a/python_tools/misc_util/figureOutMask.py b/python_tools/misc_util/figureOutMask.py
new file mode 100755
index 0000000..2bbbbd6
--- /dev/null
+++ b/python_tools/misc_util/figureOutMask.py
@@ -0,0 +1,54 @@
+#!/usr/bin/env python
+#+
+#   VIDE -- Void IDentification and Examination -- ./python_tools/setup.py
+#   Copyright (C) 2010-2014 Guilhem Lavaux
+#   Copyright (C) 2011-2014 P. M. Sutter
+#
+#   This program is free software; you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation; version 2 of the License.
+# 
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program; if not, write to the Free Software Foundation, Inc.,
+#   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#+
+
+# build a low-resolution mask given the actual galaxy positions
+
+import numpy as np
+import healpy as hp
+import os
+import shutil
+import glob
+import sys
+
+galFile = "path/to/galaxy/file"
+outMaskFile = "path/to/output/mask"
+
+nside = 128
+npix = hp.nside2npix(nside)
+mask = np.zeros((npix))
+
+for line in open(galFile):
+  line = line.split()
+  RA  = np.float(line[3])
+  Dec = np.float(line[4])
+  z   = np.float(line[5])
+
+  phi   = np.pi/180.*RA
+  theta = Dec*np.pi/180.
+  theta = np.pi/2. - Dec*np.pi/180.
+  pos = np.zeros((3))
+
+  pix = hp.ang2pix(nside, theta, phi)
+  mask[pix] = 1.
+
+print "Sky Fraction:", 1.0*len(mask[mask>0])/len(mask)
+
+hp.write_map(outMaskFile, mask)