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Processing File

Description of the FITS structure file used to store of processing of instrumental data ("proc" format). Proc-files are the essential core of data formats in Munipack. Processing actions keeps their results in the extensions of this kind of file. All other actions uses proc-file as input.

Proc-file is not created by only one action, but the extensions are created by various ones. Objects detection and aperture photometry is provided by munipack find, munipack aphot modules. The astrometry calibration is determined by munipack astrometry. The photometry calibration is determined by munipack phcal.

Proc-file specification has been developed for internal use in Munipack and follows rules introduced by original DAOPHOT. Any backward compatibility is not guarantied.

File Structure

The primary data array is followed by FIND, APERPHOT and GROWCURVE extensions. The order of the extensions can vary (use the name rather then index to access required extension).

FITS file structure including photometry
HDUEXTNAMEDescriptionAction
0Primary array (frame)
1FINDTable of detected objectsfind
2APERPHOTAperture Photometry tableaphot
3GROWCURVEGrowth curve tableaphot

Primary Array

Data in primary array is untouched during objects detection (find) and aperture photometry phase. GAIN, READNS and SATURATE keywords may by modified on user request.

Object Detection Table: FIND

The table contains detected objects.

Keywords
KeywordDescriptionUnits
EXTNAMEFIND as the identifier of this table
FWHMtypical full width at half of maximum for a detected objectpixels
THRESHthreshold for detection of peak of stars in sigmas of sky above sky mean level in a region
LOBADLower good datumADU
HIBADHigher good datumADU
RNDLORound low
RNDHIRound high
SHRPLOSharp low
SHRPHISharp high

Header Comments

Header contains additional information in more human-readable format.

Star detection parameters:
 Gain (e-/ADU)=   [..]      (see primary HDU)
 Saturation (ADU)=  [..]      (see primary HDU)
 Read noise (ADU)=   [..]      (see primary HDU)
 Lower threshold (sigma)=   [..]
 Levels range (ADU) =   [..]     ..   [..]
 Round range =  -1.00000000     ..   1.00000000
 Sharp range =  0.200000003     ..   1.00000000
 Approximate sky value =   [sky]     +-   [skysig]
 Pixels used for sky determination =       10000
Object detection table
ColumnDescriptionunit
XHorizontal coordinatepix
YVertical coordinatepix
SHARPsharp parameter
ROUNDround parameter
PEAKRATIORatio of peak to background (sky level)

The table is sorted by PEAKRATIO column in decrease order (with bright stars on top).

Aperture Photometry Table: APERPHOT

This extension contains aperture photometry of all object in a given set of apertures. Also a sky level measured in a ring shaped neighbourhood of every star is estimated.

Header Keywords

Keywords
KeywordUnitsDescription
EXTNAMEAPERPHOT as the identifier of this table
HWHMHWHM estimated by momentum method
NAPERCount of apertures
APERipixRadius of i-th aperture, i = 1..NAPER
ANNULUS1pixinner sky annulus radius in pixels
ANNULUS2pixouter sky annulus radius in pixels

Table

The aperture photometry table.

Object detection table
ColumnDescriptionunit
XHorizontal coordinate[§]pix
YVertical coordinate[§]pix
SKYcountsSky level
SKYERRcountsSky level error
APCOUNTicountsSum of counts in i-th aperture[*]
APCOUNTERRicountsStatistical error of APCOUNTi

[§] This column is a direct copy of one from FIND extension.

[*] Negative values means impossibility to determine the value. Common reasons are: the high sky background level (for faint stars) or a large aperture radius exceeding frame boundary (for stars near an edge) or saturation (for very bright stars).

Growth-Curve Photometry Table: GROWPHOT

This extension contains results of growth-curve photometry for all stars in APERPHOT table.

Header Keywords

pixpix
Keywords
KeywordUnitsDescription
EXTNAMEGROWCURVE as the identifier of this table
HWHMHWHM estimated by growth curve in pixels
RADFLX90Radius containing 90% of energy

Table

GROWPHOT extension
ColumnDescriptionunit
XHorizontal coordinatepix
YVertical coordinatepix
SKYSky level[^]count
SKYERRStatistical error of sky levelcount
GCOUNTGrowth curve estimated total sum of counts for an infinite aperture[*]count
GCOUNTERRStatistical error of APCOUNTcount
GROWFLAGClassification: used (0), not used (1) for construction of growth-curve, non-stellar object (2).

[^] Values of sky will generall differ from those from the aperture photometry table APERPHOT. Growth-curve photometry gives corrections to the sky.

Growth-Curve Table: GROWCURVE

This extension saves growth curve and derived radial profile in selected apertures.

GROWCURVE extension
ColumnDescriptionunit
RRadius of the aperturepix
GROWCURVEgrowth curve value at R
GROWCURVEERRStatistical error of growth curve
RADIALPROFILERadial profile at R

See Also

Detection of Stars, Aperture Photometry, Growth Curve Overview.