MAPS-NGP Catalog of Galaxies              (Cabanela, 1999)
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Galaxy Properties from a Diameter-Limited  Catalog
       Cabanela J.E. 1999 Ph.D. Thesis
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Abstract (of PhD Thesis)
I am using the Minnesota Automated Plate Scanner (APS) to construct two galaxy
catalogs.  The Minnesota Automated Plate Scanner Pisces-Perseus Survey (MAPS-PP)
is used to search for modern-day remnant signatures of large-scale structure
formation processes, specifically, galaxy alignments relative to surrounding
large-scale structure.  Weak evidence for such alignments is found, although the
type of alignments seen don1t strongly support any one large-scale structure
formation model.

Comparison of the MAPS-PP to pre-existing galaxy catalogs has led to the
discovery that the Uppsala General Catalog and Third Reference Catalog of
Galaxies exhibit a very strong measurement bias: their diameters are measured to
different isophotes at different galaxy inclinations.  Therefore previous
determinations of the diameter function and the internal extinction properties
of other galaxies (most of which have relied on one of these two galaxy
catalogs) have suffered from a biased diameter measurement.

I avoid this bias by using the APS data (which is obtained using automated
computer-based criteria for measuring the structural properties of images
digitized from photographic plates) to construct a catalog of over 200,000
galaxies within 30 degrees of the North Galactic Pole (the MAPS-NGP). The
MAPS-NGP is the deepest galaxy catalog constructed over such a large area of the
sky and used to re-evaluate previous investigations of the internal extinction
in galaxies.

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Data File Summary:
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This catalog contains information for 217768 unique objects (all plate overlap
duplicates have been eliminated) with major-axis diameters greater than 10
arcseconds in O (blue) and identified as "non-stellar" by the APS.  Care
has been taken to remove known sources of non-extragalactic contamination
including SAO star halos, POSS I ghost images of bright stars, low surface
brightness material around bright galaxies, and Galactic globular clusters.

The datafile (MAPSNGP.final.txt.gz) for the MAPS-NGP was translated from its
original binary encoded format to a TAB-delimited ASCII format and then GZIP
compressed to allow easy transportability between systems, regardless of
byte-order issues.

This version of the MAPS-NGP galaxy catalog preserves the full resolution of
data as stored in the Revised Minnesota Automated Plate Scanner Catalog of the
POSS I (a.k.a. StarBase2).  For more through documentation of how these image
parameters are obtained, you may visit the APS WWW site <http://aps.umn.edu/> or
look at some of the references listed at the end of this README file.

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Data File Format Summary:
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NOTE: These are not fixed-width columns, these are TAB delimited.  There is one 
  header line containing the VARIABLE_NAME of the data in each column.

A unique name for each object can be constructed using the MLN number and 
O image raster number and the convention for object references at the APS is
P[MLN]_[starnumO]. (e.g. The object with O image raster number 34523 on the POSS
I field with modified Luyten number 323 is refered to as P323_34523).

 #  VARIABLE_NAME    DESCRIPTION
 1            MLN    Modified Luyten number for field
 2           POSS    Original POSS field number
 3       starnumO    O image raster number (this is a unique number for each 
                      object on a given plate)
 4          XsctO    X position of image centroid from plate corner (in encoder
                      resolution elements [ERE])
 5          YsctO    Y position of image centroid from plate corner (in EREs)
 6            raO    Right Ascension (1950) determined from O plate image 
                      centroid
 7           decO    Declination (1950) determined from O plate image centroid
 8           diaO    Major-axis diameter (in arcseconds) from O plate image
 9          magiO    Integrated magnitude from O plate image
10          magdO    magnitude from O plate image using D-M relation for stars
11         thetaO    Major-axis position angle (N to E) from O plate image
12           ellO    Ellipticity from O plate image
13        galnodO    galnode value representing the certainty with which the
                     artificial neural network classifier has classed this 
                     object as "non-stellar" based on O plate image 
14         rmom2O    Second Moment of O plate image
15    saturationO    Percent saturation of O plate image
16        avg_inO    Average transmittance of O plate image
17       mean_sbO    Mean surface brightness (in mag/asec^2) of O plate image
18          ReffO    Effective (half-light) radius from O
19           C31O    C31 concentration index from O plate.  The ratio of the 
                       100% light radius to 50% light radius 
20           C32O    C32 concentration index from O plate.  The ratio of the 
                       100% light radius to 75% light radius 
21           C21O    C21 concentration index from O plate.  The ratio of the 
                       75% light radius to 50% light radius 
22       starnumE    E image raster number
23          XsctE    X position of image centroid from plate corner (in encoder
                      resolution elements [ERE])
24          YsctE    Y position of image centroid from plate corner (in EREs)
25            raE    Right Ascension (1950) determined from E plate image 
                      centroid
26           decE    Declination (1950) determined from E plate image centroid
27           diaE    Major-axis diameter (in arcseconds) from E plate image
28          magiE    Integrated magnitude from E plate image
29          magdE    magnitude from E plate image using D-M relation for stars
30         thetaE    Major-axis position angle (N to E) from E plate image
31           ellE    Ellipticity from E plate image
32        galnodE    galnode value representing the certainty with which the
                     artificial neural network classifier has classed this 
                     object as "non-stellar" based on E plate image 
33         rmom2E    Second Moment of E plate image
34    saturationE    Percent saturation of E plate image
35        avg_inE    Average transmittance of E plate image
36       mean_sbE    Mean surface brightness (in mag/asec^2) of E plate image
37          ReffE    Effective (half-light) radius from E
38           C31E    C31 concentration index from E plate.  The ratio of the 
                       100% light radius to 50% light radius 
39           C32E    C32 concentration index from E plate.  The ratio of the 
                       100% light radius to 75% light radius 
40           C21E    C21 concentration index from E plate.  The ratio of the 
                       75% light radius to 50% light radius 
41          Ebv_B    E(B-V) determined by bilinear interpolation of Burstein 
                       & Heiles [1982] extinction estimates.
42          Ebv_S    E(B-V) determined from Schlegel, etal [1998] extinction 
                       estimates.
43           flag    O and E imgpars flags (10*Oflag + Eflag).  Use of any 
                       image with a non-zero flag may be suspect in certain 
                       situations.
                          flag value    Cause
                                   1    bad fuz value
                                   2    bad jitter value
                                   3    bad SASORT ellipticity 
                                        (note: ellipticities are recomputed
                                         during data reduction, so this flag
                                         is somewhat unimportant)
                                   4    image crosses stripe boundary, likely 
                                        to be clipped (inaccurate image
                                        parameters likely)
                                   6    computed sky density is negative  
44          color    O-E color of the object computed using intergrated
                       magnitudes. 
45         colord    O-E color of the object computed using D-M relation
                       magnitudes. 
46           dens    Estimated local surface density of MAPS-NGP galaxies
                       (in galaxies/degree^2)

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References:
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Burstein, D. and Heiles, C. 1982, AJ, 87, 1165.
Cabanela, J. E. 1999, Ph.D. Thesis, University of Minnesota.
Cabanela, J. E. and Aldering, G. L. 1998, AJ, 106, 1094. 
Cabanela, J. E. and Dickey, J. M. 1999, AJ, 118, 46. 
Pennington, R. L., Humphreys, R. M., Odewahn, S. C., Zumach, W., Thurmes, P. M. 
    1993, PASP, 105, 521.
Odewahn, S. C., Humphreys, R. M., Aldering, G., and Thurmes, P. 1993, PASP, 
    105, 1354.
Odewahn, S. C., Stockwell, E. B., Pennington, R. L., Humphreys, R. M., and 
    Zumach, W. A.  1992, AJ, 103, 318.
Odewahn, S. C.  and Aldering, G. L. 1995, AJ, 110, 2009. 
   [NOTE: Odewahn & Aldering 1995 provide an incorrect definition for APS
          concentration indicies, the correct defintions are those provided 
          in this README document.] 
Schlegel, D., Finkbeiner, D.P., and Davis, M. 1998, AJ, 500, 525. 

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Current (09/2001) Author Contact Information
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Dr. Juan Cabanela                Email: See web page below
Haverford College                 Work: (610) 896-1321
370 Lancaster Avenue               Fax: (610) 896-4904
Haverford, PA 19041                WWW: http://www.haverford.edu/physics-astro/Cabanela/