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mkobsfile noao.digiphot.photcal


NAME · USAGE · PARAMETERS · DESCRIPTION · OUTPUT · EXAMPLES
TIME_REQUIREMENTS · BUGS · SEE_ALSO

NAME

mkobsfile -- prepare a single observations file from a list of APPHOT/DAOPHOT files containing observations of objects in a single field

USAGE

mkobsfile photfiles idfilters observations

PARAMETERS

photfiles
The APPHOT or DAOPHOT output database(s) containing the object magnitudes. In the case of MKOBSFILE these databases are normally created by the DAOPHOT PEAK, NSTAR or ALLSTAR tasks, but may also have been written by the APPHOT QPHOT and PHOT tasks or the DAOPHOT PHOT task.
idfilters
The list of filters separated by whitespace or commas which define a complete observation.
observations
The output observations file suitable for input to FITPARAMS or EVALFIT/INVERTFIT.
wrap = yes
Format the output observations file for easy reading ? If wrap = yes then the observations for each filter are written on a separate line and the * character in column 1 is interpreted as a continutation character. Otherwise all the data for each object is written to a single line where the maximum size of a line is the current value of SZ_LINE.
imsets = "STDIN"
The input/output image set file which lists the observations of each field, assigns a name to each field, and tells MKOBSFILE which images belong to the same observation of that field. Only observations corresponding to the images listed in imsets will be extracted from photfiles . If imsets is the standard input "STDIN", MKOBSFILE prompts the user for the field name and the associated list of images. Otherwise the observations are assumed to be listed in imsets , 1 observation per line with the field name in column 1, a colon in column 2, followed by, the names of the images of that field belonging to that observation. The format of imsets is described in detail below.
obsparams = ""
The name of an optional text file containing the filter ids, exposure times, airmasses, and times of observation for each image whose values are either not stored or incorrectly stored in photfiles . If obsparams is the standard input "STDIN", MKOBSFILE prompts the user for the correct filter id, exposure time, airmass, and time of observation for each image in each image set. Otherwise the observing parameters for each image are assumed to be listed in obsparams , 1 image per line, with the image name in column 1 and the filter ids, exposure times, airmasses, and times of observation in the columns defined by obscolumns . The image names must match those in imsets . Images which have no entries in obsparams are assigned the values stored in photfiles .
obscolumns = "3 4 5"
The list of numbers separated by commas or whitespace specifying which columns in obsparams contain the correct filter ids, expsoure times, airmasses, and times ob observation respectively. The number 0 may be used as a place holder in the obscolumns string. For example, to correct only the photfiles airmass values, obscolumns should be set to "0 0 column 0", where column is the airmass column number. The default value of obscolumns corresponds to the format of the default obsparams file produced by MKIMSETS.
minmagerr = 0.001
The error that will be assigned to a non-INDEF valued magnitude measurement if the recorded error is less than minmagerr .
shifts = "STDIN"
The name of the text file specifying the x-y shifts to be added to the x-y positions of all objects in an image before position matching (the original x's and y's are retained in the output). If shifts is the standard input "STDIN", MKOBSFILE prompts the user for the correct x and y shift for each image in each image set. Otherwise the shifts are assumed to be listed in shifts , 1 image per line, with the name of the image in column 1, followed by the the x and y shifts in columns 2 and 3 respectively. Image names must match those in imsets . Images for which no shift is supplied are assigned x and y shifts of zero.
apercors = "STDIN"
The name of the text file specifying the aperture corrections to be added to the extracted magnitudes for each image before writing the magnitudes to observations . If apercors is the standard input "STDIN", MKOBSFILE prompts the user for the correct aperture correction for each image in each image set. Otherwise the aperture corrections are assumed to be listed in apercors , 1 image per line with the name of the image in column 1, followed by the aperture correction in magnitudes in column 2. The image names must match those in the imsets . Images for which no aperture correction is supplied are assigned a default value of 0.0.
aperture = 1
The aperture number in photfiles for which the magnitude is extracted, if the magnitudes were measured through more than one aperture. By default the magnitude through the first aperture is extracted.
tolerance = 5.0
The tolerance in pixels for matching objects in the same observation, but different images. MKOBSFILE extracts the x and y coordinates of each object in each image of a given observation from photfiles , adds the shift for that image in shifts to the extracted x-y coordinates, and matches the objects to within tolerance pixels. Missing objects are assigned INDEF entries in observations . If tolerance is less than or equal to 0 no coordinate matching is done, and objects are matched in order of occurrence with missing objects being assigned INDEF values.
allfilters = no
Output only objects which are sucessfully matched in all the filters specified by idfilters ?
verify = no
Verify any data entered interactively by the user ?
verbose = yes
Print status, warning, and error messages ?

DESCRIPTION

MKOBSFILE takes a list of APPHOT or DAOPHOT database files photfiles , each containing observations of one or more objects in one or more fields and prepares an observation file observations . By default MKOBSFILE prompts the user for the 1) name of each observation of each star field (imsets ), 2) the names of the images belonging to each observation of each starfield (imsets ) , 3) shifts for each image in each observation (shifts ), and 4) aperture corrections for each image in each observation (apercors ). MKOBSFILE is optimized for creating a single observations file containing observations of many stars in a single star field. MKOBSFILE IS THE PREPROCESSOR OF CHOICE FOR PREPARING MULTI-OBJECT SINGLE FIELD OBSERVATIONS OF A CROWDED STAR FIELD.

MKOBSFILE performs the following functions: 1) extracts the quantities image name, x and y position, exposure time, filter id, airmass, time of observation, magnitude and magnitude error from photfiles , 2) corrects erroneous or missing values of the filter id, exposure time, airmass, and time of observation in photfiles , 3) associates each field with one or more sets of images of that field taken through different filters, 4) matches individual objects within a given image set by order of occurrence or x-y position and, 5) assigns a unique name to each object in each field.

The image set file imsets assigns a name to each field. For fields containing only a single standard star this name should match the name of the standard star in the standard star catalog. For fields containing more than one star, MKOBSFILE constructs a unique name for each object in the field by adding a sequence number to the field name in imsets , which if the star is a standard star the user must later edit. For example the fourth star in the field "M92" will be assigned the name "M92-4" in observations . If this star is a standard star and its true name is "IX-10" in the standard star catalog, then the user must change "M92-4" to "IX-10" in observations . Imsets also tells MKOBSFILE which images in photfiles are images of the same region of the sky belonging to the same observation. By default MKOBSFILE defines the image set file interactively by prompting the user for input. If the number of observations is small the user should leave imsets set to "STDIN" and enter the image sets as prompted. If the number of observations is large the user should consider using MKIMSETS and MKNOBSFILE to create their observations file. The format of imsets is described in detail below.

Values of the filter ids , exposure times, airmasses, and times of observation which are missing or incorrect in photfiles , can be corrected by reading the correct values from the columns obscolumns in the file obsparams . The format of obsparams is described in detail below. If obsparams is the standard input "STDIN" then MKOBSFILE will prompt the user for the filter ids, exposure times, airmasses, and times of observation for each image in each image set.

MKOBSFILE matchs the objects in different images within the same observation either by order of occurrence if tolerance is less than or equal to 0.0, or by x-y position. Matching by position is done by identifying which objects in each of the images of a given field and observation set are within tolerance pixels of each other. The user may supply an optional file of x and y shifts shifts to be added to the object positions prior to matching. The format of shifts is described in detail below. If the parameter allfilters is "yes", only objects which are matched in all the filters idfilters are output. If shifts is the standard input "STDIN" then MKOBSFILE will prompt the user for the x and y shifts for each image in each image set.

MKOBSFILE permits the user to supply an optional file of aperture corrections apercors containing the magnitude corrections to be added to the instrumental magnitudes in photfiles . The format of apercors is described in detail below. If apercors is the standard input "STDIN", then MKOBSFILE will prompt the user for the aperture correction for each image in each image set.

Each new observations file created by MKNOBSFILE has an associated format description file listing the column names and numbers in observations , of the fields extracted from photfiles . This file, referenced by its parent observations file name, can be used as input to the MKCONFIG task. The actual name of the format description file on disk is constructed by prepending the observations file name observations with the string "f" and appending the string ".dat". For example if a new observations file called "m92long" is created by MKOBSFILE, a format description file called "fm92long.dat" will also be created. Any pre-existing format description file of that name, which does not have an associated observations file, will be deleted.

THE IMSETS FILE

The imsets file lists the observations of each field which are to be extracted from photfiles , assigns a name to each field, and informs MKOBSFILE which images belong to the same observation of that field. Observations are listed in imsets , 1 observation per line with the field name in column 1, a colon in column 2, followed by the names of the images of that field for that observation separated by whitespace.

The field name is used to generate the object names in observations . If there is only a single measured object in a field, then the name of that object in observations will be the name of the field. If the single object is a standard star, the user should edit imsets so that the field name is the same as the name of the standard star in the standard star catalog. If a stellar field contains more than one measured object, MKOBSFILE generates names of the form "field-#" where "field" is the field name and "#" is a sequence number. For example the fourth star in the field "M92" is assigned the name "M92-4" in observations . If the star is a standard star, the user must edit the object names in observations to match those in the standard star catalog.

Any number of observations may have the same field name. This normally occurs, for example, when multiple observations of s single standard star or standard star field are made at several airmasses.

If there are no filter ids in photfiles or obsparams then the images in each image set are assigned the filter ids in idfilters in order of occurrence, or user input if imsets is "STDIN".

The imsets file for a set of 9 UBV frames of the globular cluster M92 is listed below. The U, B and V images for a set of long, medium and short exposure image sets of M92 are listed in columns 2, 3 and 4 respectively.

	M92L :  m92ul	  m92bl	   m92vl
	M92M :  m92um	  m92bm	   m92vm
	M92S :  m92us	  m92bs	   m92vs

THE OBSPARAMS FILE

The file obsparams lists the correct filter ids, exposure times, airmasses, and times of observation for each image, 1 image per line, with the image name in column 1, and the remaining quantities in the columns specified by obscolumns . The images names must correspond to those in imsets .

A sample corrections file obsparams for the previous set of UBV M92 observations is shown below. The filter ids, exposure times, airmasses, and times of observation for all the images were correctly read into photfiles from the image headers with the exception of the filter id, exposure time, airmass, and time of observation for the V frame of "M92M". The correct filter id, exposure time, airmass, and time of observation is supplied in obsparams with obscolumns set to "2 3 4 5" as follows.

	m92vm    3 300 1.256 03:14:20.4

Zero can be used as a place holder in obscolumns as in the following example where the user wants to correct only the exposure time and the airmass but leave the filter id and time of observation alone. In this case obscolumns is set to "0 2 3 0" and obsparams looks as follows.

	m92vm    300 1.256

THE SHIFTS FILE

The file shifts lists the shifts for each image, 1 shift per line, with the image name in column 1 and the x and y shifts in columns 2 and 3 respectively. The image names in shifts must match those in imsets .

A sample shifts file for the previous set of UBV M92 observations is listed below. The U observations are used as the position reference and so are assigned x-y shifts of 0. The long and middle exposure B and V frames have small but significant shifts with respect to the U frames and so are included in the shifts file. The short exposure images are not significantly shifted with respect to one another and so are not included in the shifts file.

	m92ul	  0.0	 0.0
	m92bl	 -5.2	-2.9
	m92vl	-10.0	-5.6
	m92um	  0.0	 0.0
	m92bm	  4.0	-1.1
	m92vm	  6.3	-2.7

THE APERCORS FILE

The file apercors lists the aperture corrections for each image, 1 aperture correction per line, with the image name in column 1 and the aperture correction in magnitudes in column 2 respectively. The image names in apercors must match those in imsets .

A sample apercors file for the previous set of UBV observations is shown below.

	m92ul	  -0.15
	m92bl	  -0.09
	m92vl	  -0.05
	m92um	  -0.14
	m92bm	  -0.10
	m92vm	  -0.06
	m92us	  -0.16
	m92bs	  -0.10
	m92vs	  -0.04

OUTPUT

The output observations file has the following format. Note that the exposure times are assumed to have been normalized either prior to executing MKOBSFILE or by using the contents of the obsparams file, and so are not included in observations .

	# FIELD   FILTER  OTIME   AIRMASS  X     Y     MAG   MERR

	  M92L-1  1       .       .        .     .     .     .
	  *       2       .       .        .     .     .     .
	  *       3       .       .        .     .     .     .
	  M92L-2  1       .       .        .     .     .     .
	  *       2       .       .        .     .     .     .   
	  *       3       .       .        .     .     .     .
	  .
	  .
	  .
	  M92L-N  1       .       .        .     .     .     .
	  *       2       .       .        .     .     .     .
	  *       3       .       .        .     .     .     .
	  .......................................................
	  M92M-1  1       .       .        .     .     .     .
	  *       2       .       .        .     .     .     .
	  *       3       .       .        .     .     .     .
	  M92M-2  1       .       .        .     .     .     .
	  *       2       .       .        .     .     .     .   
	  *       3       .       .        .     .     .     .
	  .
	  .
	  .
	  M92M-N  1       .        .        .     .     .     .
	  *       2       .        .        .     .     .     .
	  *       3       .        .        .     .     .     .
	  ........................................................
	  M92S-1  1       .        .        .     .     .     .
	  *       2       .        .        .     .     .     .
	  *       3       .        .        .     .     .     .
	  M92S-2  1       .        .        .     .     .     .
	  *       2       .        .        .     .     .     .   
	  *       3       .        .        .     .     .     .
	  .
	  .
	  .
	  M92S-N  1       .        .        .     .     .     .
	  *       2       .        .        .     .     .     .
	  *       3       .        .        .     .     .     .
	  ........................................................

The accompanying format description file has the following format.

# Declare the observations file variables

observations

T1            3              # the time of observation in filter 1
X1            4              # airmass in filter 1
x1            5              # x coordinate in filter 1
y1            6              # y coordinate in filter 1
m1            7              # instrumental magnitude in filter 1
error(m1)     8              # magnitude error in filter 1

T2            10             # the time of observation in filter 2
X2            11             # airmass in filter 2
x2            12             # x coordinate in filter 2
y2            13             # y coordinate in filter 2
m2            14             # instrumental magnitude in filter 2
error(m2)     15             # magnitude error in filter 2

T3            17             # time of observation in filter 3
X3            18             # airmass in filter 3
x3            19             # x coordinate in filter 3
y3            20             # y coordinate in filter 3
m3            21             # instrumental magnitude in filter 3
error(m3)     22             # magnitude error in filter 3

EXAMPLES

1. Prepare an observations file from a set of observations of an open cluster computed by the DAOPHOT ALLSTAR task. There is one ALLSTAR output file per filter, with each file containing observations of several hundred cluster stars. Position matching is required. The magnitudes have already been normalized to unit exposure time by the earlier PHOT step, and the filter ids and airmasses read from the image headers and written to the ALLSTAR files are correct.

	ph> assemble the following information

	    ... the name of the image associated with each allstar file

	    ... the appropriate x-y shifts for each image

	    ... the aperture corrections for each image

	ph> mkobsfile ocl*.als.* "1,2,3" ocl.obs tol=4.0

	    ... for each complete observation mkobsfile prompts for the
	        field name and the associated image names (in this case
		3 since there are 3 filters in idfilters) taken through
		each filter
	    ... the end-of-file character <EOF> typed in response to the
	        query for the next image set name terminates image set
		set entry

	    ... next mkobsfile prompts for an x and y shift for each
		image in each image set
	    ... the end-of-file character <EOF> typed in response to the
	        query for the next image x-y shift terminates image shift
		entry

	    ... next mkobsfile prompts for an aperture correction for each
		image in each image set
	    ... the end-of-file character <EOF> typed in response to the
	        query for the next image aperture correction terminates
		aperture correction entry

2. Prepare an observations file from a set of globular cluster standard star observations computed with the DAOPHOT PHOT task. The three PHOT output files contain UBV measurements for the all the standard stars in the globular cluster field plus a few extraneous objects. Position matching is required, but since the filter to filter shifts are small no x-y offsets are required for position matching. Since these objects are standard stars, aperture corrections are not required. The user forgot to define the filter id, exposure time, airmass, and time of observation image header keyword parameters inside DAOPHOT, so the magnitudes are not normalized for exposure time, and the airmasses, filter ids, and times of observation are incorrect.

	ph> assemble the following information

	    ... the name of the image associated with each phot file

	    ... the filter id, exposure time, and airmass of each image

	ph> mkobsfile gcl*.mag.* "1,2,3" gcl.obs obsparams="STDIN"\
	    obcolumns="2 3 4 5" shifts="" apercors="" tolerance=5.0

	    ... mkobsfile prompts the user for a field name and an image
	        name corresponding to each filter as above
	    ... the end-of-file character <EOF> typed in response to the
	        query for the next image set name terminates image set
		set entry

	    ... mkobsfile prompts the user for the correct filter id,
	        exposure time, airmass, and time of observation for each
		image in each image set
	    ... the end-of-file character <EOF> typed in response to the
	        query for the next set of corrections terminates image
		corrections entry

TIME REQUIREMENTS

BUGS

SEE ALSO

mkimsets,mkphotcors,mknobsfile


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