VizieR catalog V/164 derived products

Products and img examples

• HEALPix Multi Order Coverage (MOC): moc.fits
• HEALPix Multi Order Coverage (MOC) at order 8: moc.o8.fits
• HEALPix Multi Order Coverage (MOC) from chi2-MOM: densmom.moc.fits
• HEALPix count Sky Map: countmap.fits
• HEALPix count Sky Map at order 8: countmap.o8.fits
• HEALPix chi-square density Multi Order Map (MOM): densmom.fits
• Small (88x44 pixels):
  • moc (order 2)
  • moc (order 4)
  • moc (from chi2-MOM)
  • count map (order 2; linear)
  • count map (order 2; linear log)
  • count map (order 4; linear)
  • count map (order 4; linear log)
  • chi-square density MOM (linear)
  • chi-square density MOM (linear log)
• Medium (600x300 pixels):
  • moc (order 7)
  • moc (from chi2-MOM)
  • count map (order 7; linear)
  • count map (order 7; linear log)
  • chi-square density MOM (linear)
  • chi-square density MOM (linear log)
• Large (1200x600 pixels):
  • moc (order 8)
  • moc (from chi2-MOM)
  • count map (order 8; linear)
  • count map (order 8; linear log)
  • chi-square density MOM (linear)
  • chi-square density MOM (linear log)

Info

All products are so far based on the VizieR computed _RAJ200/_DEJ2000 columns.

The chi2-MOM is particularly suited for catalogs with a large number of sources.
It is then more compact than the count map at order 11 and removes the white noise, thus providing a smoother map.
See e.g. the vsx (50 MB vs 1.1 MB).

Libraries used on server side

• cds-healpix-rust
• cds-moc-rust
• cds-fitstable-rust
• cds-mapproj-rust

Reproduce (in equatorial) from tools using the same core libraries

Command line tools (CLI)

See:

• moc-cli to manipulate MOCs, e.g.:

# Download a MOC
> wget -0 moc.fits 'http://vizcat.cds.unistra.fr/catalog/V/164/moc'
# Degrade it at order 7
> moc op degrade 7 moc.fits fits moc.o7.fits
# Create the degraded resolution quick view at resolution 600x300 (WARNING: in Equatorial, not in Galactic
> moc view moc.o7.fits moc.o7.png allsky 300
# Create the full resolution quick view at resolution 1600x800 (WARNING: in Equatorial, not in Galactic
> moc view moc.fits moc.png allsky 800
        

• hpx-cli to manipulate Skymaps and MOMs, e.g.:

# Download a count map
> wget -O countmap.fits 'http://vizcat.cds.unistra.fr/catalog/V/164/countmap'
# Create the quick view at resolution 1600x800 (WARNING: in Equatorial, not in Galactic
> hpx map view countmap.fits countmap.png allsky 800
# Download a density MOM
> wget -O densmom.fits 'http://vizcat.cds.unistra.fr/catalog/V/164/densmom'
# Create the quick view at resolution 1600x800 (WARNING: in Equatorial, not in Galactic
> hpx mom view densmom.fits densmom.png allsky 800
# Create a FITS BINTABLE version of the MOM
> hpx mom convert densmom.fits densmom.bintable.fits bintable
        

Python

See:

• MOCPy to manipulate MOCs;

from mocpy import MOC
# Download a MOC
moc = MOC.from_vizier_table("V/164") TODO: CHECK EXISTS??!!
# Degrade it at order 7
degraded_moc = moc.degrade_to_order(7)
# Create the degraded resolution quick view at resolution 600x300
degraded_moc.display_preview(y_size=300)
        

• CDS HEALPix Python to manipulate Skymaps (MOMs not supported yet)

from urllib.request import urlretrieve
from cdshealpix.skymap import Skymap
# Download a count map
urlretrieve(
    url="http://vizcat.cds.unistra.fr/catalog/V/164/countmap",
    filename="countmap.fits"
)
countmap = Skymap.from_fits("countmap.fits")
countmap.quick_plot(size=300)
        

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