From mhanner@velo.astro.umass.edu  Thu Nov 30 15:15:18 2006
X-Original-To: raugh@icarus.astro.umd.edu
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Delivered-To: raugh@astro.umd.edu
Date: Thu, 30 Nov 2006 15:25:50 -0500
From: mhanner@velo.astro.umass.edu
To: ludmilla@astro.umd.edu, raugh@astro.umd.edu
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Corrections to the Description of the "addenda" files in the IR Photometry
  database:

     In the 3 label files, addenda1.lbl, addenda2.lbl, addenda3.lbl
     replace the paragraph under DESCRIPTION with the following:

     DESCRIPTION
       This data set compiles the infrared photometry from the Univ.
       Minnesota Halley monitoring campaign.  These data were submitted to
       the IHW IRSN after the original cutoff date for archiving.  The 
       full data record for each of the 47 observations is split across
       three tables, corresponding to Tables I,II,III in Gehrz and Ney
       (1992).  Records are in the same chronological order in all three
       tables.
          Table I (addenda1.tab) gives the observational parameters for each
	       date
	  Table II (addenda2.tab) presents the infrared magnitudes
	  Table III (addenda3.tab) summarizes the infrared properties
	      derived from the observations.  See Gehrz and Ney (1992) 
	      for the definitions of the tabulated quantities.

       The photometric system and calibration are discussed in Gehrz & Ney
       (1992) and Gehrz et al. (2005)

     REFERENCES
       Gehrz, R.D. and Ney, E.P, 1992, Icarus 100, 162-186
       Gehrz, R.D., Hanner, M.S., Homich, A.A., and Tokunaga, A.T. 
         2005, Astronomical Journal, 130, 2383-2391


I suggest repeating the same DESCRIPTION in all 3 of these files

Comments for the specific column headings of the 3 addenda.lbl files follow:

I have checked the description of the column headers against Gehrz & Ney 1992

 addenda1.lbl
    Col 10 and 11: problem with the definition of scattering angle
      The sun-comet-Earth angle is usually defined as the phase angle, not
      the scattering angle  (i.e., phase angle at opposition is 0 deg)
   **Please discuss this point with Ludmilla and decide how best to describe
   scattering angle.  Col 10 really is the scattering angle, and Gehrz
   consistently uses scattering angle, not phase angle, in his discussions.

   Col. 12 BEAM_DIAMETER
       I recommend inserting the actual size of the rectangular beams for
       each instrument here, as you have them in Table 2 (addenda2.lbl
    ==>> But note that " means arcsec not inches !!

  Col. 14
     change the DESCRIPTION to read:
   the multiplying factor required to correct for coma emission in the
   reference beam:  4*..etc

 Col 15
    change DESCRIPTION to read
  Multiplying factor to normalize measured coma emission to circular
  diaphragm of 20-arcsec diameter: 20/BEAM DIAMETER

addenda2.lbl
  
  Column 6
     The beam sizes of the instruments are in arcsec, not inches  !!

  Column 8 thru 30
     I question the use of the term "raw" magnitudes.  To me, a "raw"
     magnitude is an instrumental magnitude, not corrected for anything.
     These are calibrated magnitudes, corrected for airmass and reduced
     to a standard photometric system. 

     So, I recommend removing the word "raw" from each of these columns,
     and just stating "photometric magnitude...corrected only for atmospheric
     extinction." 

addenda3.lbl

   Column 8:
     DESCRIPTION   Equilibrium blackbody temperature for comet's heliocentric 
     distance

  Columnm 10
    DESCRIPTION  "Superheat", the excess color temperature above the blackbody
    temperature:  T_c/T_BB 
    
  Column 11
    DESCRIPTION  Observed apparent maximum emission from the infrared continuum
    in Watt per cm^2  (Maximum of the [flux * wavelength] curve)

 Column 12
    DESCRIPTION  Observed apparent maximum emission from the scattered
    solar component in Watt per cm^2  (Maximum of the [flux * wavelength] 
    curve)

 Column 13
   DESCRIPTION Albedo of the coma at the scattering angle of observation

   {spelling of albedo; clarification that this is not the ususal
   definition of albedo, but is referenced to the anglle of observation}

 Column 17  coma, not comma

 Column 18

   The term "total infrared emission" is confusing.  It really is the
   quantity  (Flux * Wavelength)  at the wavelength where this quantity
   has its maximum - which is not the same as the maximum of the flux alone.
   It is the same quantity as in column 11, with all the corrections applied.
   and it really is the maximum IR energy, in W/cm^2

   So, I suggest saying
   DESCRIPTION Maximum emission (Flux * wavelength) from Column 11, corrected
   to unit geocentric and heliocentric distance and 20 arcsec beam diameter.
   in Watt per cm^2

   => I suggest you discuss this label with Ludmilla