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pexamine noao.digiphot.apphot


NAME · USAGE · PARAMETERS · PLOTTING_PARAMETERS · DESCRIPTION
CURSOR_COMMANDS · EXAMPLES · TIME_REQUIREMENTS · BUGS · SEE_ALSO

NAME

pexamine -- interactively examine or edit a photometry catalog

USAGE

pexamine input output image

PARAMETERS

input
The name of the input photometry catalog. Input may be either an APPHOT/DAOPHOT text database file or an STSDAS binary table database.
output
The name of the edited output catalog. Output is either an APPHOT/DAOPHOT text database or an STSDAS binary table database depending on the file type of input . If output = "" no output catalog is written.
image
The name of the input image corresponding to the input photometry catalog. If image is "" no image will be attached to PEXAMINE and some interactive catalog examining commands will not be available. All the catalog editing commands however are still available.
deletions = ""
The name of an optional output deletions photometry catalog. Deletions is either an APPHOT/DAOPHOT text database or an STSDAS binary table database depending on the file type of input . If deletions is "" no deletions file is written.
photcolumns = "apphot"
The list of standard photometry columns that are loaded when pexamine is run. The options are listed below.
"apphot"
The standard columns for the APPHOT package. The current list is ID, XCENTER, YCENTER, MSKY, MAG, and MERR. If any of these columns are multi-valued, (as in the case of magnitudes measured through more than one aperture), the first value is selected. The standard list may easily be extended at user request.
"daophot"
The standard columns for the DAOPHOT package. The current list is GROUP, ID, XCENTER, YCENTER, MSKY, MAG, MERR, CHI, SHARP and NITER. If any of these columns are multi-valued, (as in the case of magnitudes measured through more than one aperture), the first value is selected. The standard list may easily be extended at user request.
user list
A user supplied list of standard columns. Column names are listed in full in either upper or lower case letters, separated by commas. If more than one value of a multi-valued column is requested the individual values must be listed separately as in the following example ID, XCENTER, YCENTER, MAG[1], MERR[1], MAG[2], MERR[2].

Photcolumns can be changed interactively from within PEXAMINE at the cost of rereading the database.

xcolumn = "mag" (magnitude), ycolumn = "merr" (magnitude error)
The names of the two columns which define the default X-Y plot. Xcolumn and ycolumn must be listed in photcolumns or usercolumns but may be changed interactively by the user. If either xcolumn or ycolumn is a multi-valued quantity and more than one value is listed in photcolumns or usercolumns then the desired value number must be specified explicitly in, e.g. MAG[2] or MERR[2].
hcolumn = "mag" (magnitude)
The name of the column which defines the default histogram plot. Hcolumn must be listed in photcolumns or usercolumns but may be changed interactively by the user. If hcolumn is a multi-valued quantity and more than one value is listed in photcolumns or usercolumns then the desired value must be specified explicitly in hcolumn , e.g. MAG[2].
xposcolumn = "xcenter", yposcolumn = "ycenter"
The names of the two columns which define the X and Y coordinates in image of the objects in the catalog. This information is required if the image display and image cursor are to be used to visually identify objects in the image with objects in the catalog or if plots of image data are requested. Xposcolumn and yposcolumn must be listed in photcolumns or usercolumns but may be changed interactively by the user.
usercolumns = ""
The list of columns loaded into memory in addition to the standard photometry columns photcolumns . The column names are listed in full in upper or lower case letters and separated by commas. Usercolumns can be changed interactively from within PEXAMINE at the cost of rereading the database.
first_star = 1
The index of the first object to be read out of the catalog.
max_nstars = 5000
The maximum number of objects that are loaded into memory at task startup time, beginning at object first_star . If there are more than max_nstars in the catalog only the first max_nstars objects are read in.
match_radius = 2.0
The tolerance in pixels to be used for matching objects in the catalog with objects marked on the display with the image cursor.
graphics = "stdgraph"
The default graphics device.
use_display = yes
Use the image display? Users without access to an image display should set use_display to "no".
icommands = ""
The image display cursor. If null the standard image cursor is used whenever image cursor input is requested. A cursor file in the appropriate format may be substituted by specifying the name of the file. Also the image cursor may be changed to query the graphics device or the terminal by setting the environment variable "stdimcur" to "stdgraph" or "text" respectively.
gcommands = ""
The graphics cursor. If null the standard graphics cursor is used whenever graphics cursor input is requested. A cursor file in the appropriate format may be substituted by specifying the name of the file.

PLOTTING PARAMETERS

PEXAMINE supports five types of plots 1) an X-Y column plot 2) a histogram column plot 3) a radial profile plot 4) a surface plot and 5) a contour plot. Each supported plot type has its own parameter set which controls the appearance of the plot. The names of the five parameter sets are listed below.

    cntrplot	Parameters for the contour plot
    histplot	Parameters for the column histogram plot
    radplot	Parameters for radial profile plot
    surfplot	Parameters for surface plot
    xyplot	Parameters for the X-Y column plot	

The same parameters dealing with graph formats occur in many of the parameter sets while some are specific only to one parameter set. In the summary below those common to more than one parameter set are shown only once. The characters in parenthesis are the graph key prefixes for the parameter sets in which the parameter occurs.

angh = -33., angv = 25. (s)
Horizontal and vertical viewing angles in degrees for surface plots.
axes = yes (s)
Draw axes along the edge of surface plots?
banner = yes (chrsx)
Add a standard banner to a graph? The standard banner includes the IRAF user and host identification and the date and time.
box = yes (chrx)
Draw graph box and axes?
ceiling = INDEF (cs)
Ceiling data value for contour and surface plots. A value of INDEF does not apply a ceiling. In contour plots a value of 0. also does not apply a ceiling.
dashpat = (c)
Dash pattern for negative contours.
fill = no (yes) (c) (hrx)
Fill the output viewport regardless of the device aspect ratio?
floor = INDEF (cs)
Floor data value for contour and surface plots. A value of INDEF does not apply a floor. In contour plots a value of 0. also does not apply a floor.
grid = no (rx)
Draw grid lines at major tick marks?
interval = 0.(c)
Contour interval. If 0.0, a contour interval is chosen which places 20 to 30 contours spanning the intensity range of the image.
label= no (c)
Label the major contours in the contour plot?
logx = no, logy = no (rx) (hrx)
Plot the x or y axis logarithmically? The default for histogram plots is to plot the y axis logarithmically.
majrx=5, minrx=5, majry=5, minry=(chrx)
Maximum number of major tick marks on each axis and number of minor tick marks between major tick marks.
marker = "box" (rx)
Marker to be drawn. Markers are "point", "box", "cross", "plus", "circle", "hline", "vline" or "diamond".
nbins = (h)
The number of bins in, or resolution of, histogram plots.
ncolumns = 21, nlines = (cs)
Number of columns and lines used in contour and surface plots.
ncontours = (c)
Number of contours to be drawn. If 0, the contour interval may be specified, otherwise 20 to 30 nicely spaced contours are drawn. A maximum of 40 contours can be drawn.
nhi = -(c)
If -1, highs and lows are not marked. If 0, highs and lows are marked on the plot. If 1, the intensity of each pixel is marked on the plot.
rinner = 0, router = 8
The inner and outer radius of the region whose radial profile is to be plotted.
round = no (chrx)
Extend the axes up to "nice" values?
szmarker = (rx)
Size of mark except for points. A positive size less than 1 specifies a fraction of the device size. Values of 1, 2, 3, and 4 signify default sizes of increasing size.
ticklabels = yes (chrx)
Label the tick marks?
top_closed = no (h)
Include z2 in the top histogram bin? Each bin of the histogram is a subinterval that is half open at the top. Top_closed decides whether those pixels with values equal to z2 are to be counted in the histogram. If top_closed is yes, the top bin will be larger than the other bins.
x= INDEF, x2 = INDEF, y1 = INDEF, y2 = INDEF (hrx)
Range of graph along each axis. If INDEF the range is determined from the data range. The default y1 for histogram plots is 0.
zero = 0. (c)
Greyscale value of the zero contour, i.e., the value of a zero point shift to be applied to the image data before plotting. Does not affect the values of the floor and ceiling parameters.
z= INDEF, z2 = INDEF (h)
Range of pixel values to be used in histogram. INDEF values default to the range in the region being histogramed.

DESCRIPTION

PEXAMINE is a general purpose tool for interactively examining and editing photometry catalogs produced by the APPHOT or DAOPHOT packages. It is intended to aid the user in assessing the accuracy of the photometry, in diagnosing problems with particular catalog objects, in searching the photometry data for relationships between the computed quantities, and in editing the catalog based on those observed relationships. PEXAMINE is intended to complement the more batch oriented editing facilities of the SELECT task.

PEXAMINE takes the input catalog input and the corresponding image image (if defined) and produces an output catalog of selected objects output (if defined) and an output catalog of deleted objects deletions (if defined). The input catalog may be either an APPHOT/DAOPHOT text database or an ST binary table database. The file type of the output catalogs output and deletions is the same as that of input .

READING IN THE DATA

PEXAMINE reads the column data specified by photcolumns and usercolumns for up to max_nstars beginning at star first_star into memory. The photcolumns parameter defines the list of standard photometry columns to be loaded. If "daophot" or "apphot" is selected then the standard columns are GROUP, ID, XCENTER, YCENTER, MSKY, MAG, MERR, CHI, SHARP and NITER and ID, XCENTER, YCENTER, MSKY, MAG and MERR respectively. Otherwise the user must set photcolumns to his or her own preferred list of standard photometry columns. Non-standard columns may also be specified using the parameter usercolumns . Valid column lists contain the full names of the specified columns in upper or lower case letters, separated by commas. Either photcolumns or usercolumns may be redefined interactively by the user after the task has started up, but only at the expense of rereading the data from input .

PEXAMINE will fail to load a specified column if that column is not in the photometry database, is of a datatype other than integer or real, or adding that column would exceed the maximum number of columns limit currently set at twenty. The user can interactively examine the list of requested and loaded standard photometry columns, as well as list all the columns in the input after the task has started up.

GRAPHICS AND IMAGE COMMAND MODE

PEXAMINE accepts commands either from the graphics cursor gcommands (graphics command mode) or the image display cursor icommands if available (image command mode). PEXAMINE starts up in graphics command mode, but all the interactive commands are accessible from both modes and the user can switch modes at any time assuming that the use_display parameter is set to "yes".

PEXAMINE interprets the cursor position in graphics command mode differently from how it interprets it in image command mode. In graphics command mode the cursor coordinates are the position of the cursor in the current plot, whereas in image command mode they are the x and y coordinates of the cursor in the displayed image. For example, if the user issues a command to PEXAMINE to locate the object in the catalog nearest the point in the current X-Y plot marked by the graphics cursor, PEXAMINE does so by searching the data for the object whose values of xcolumn and ycolumn most closely match those of the current cursor position. If the user issues a command to PEXAMINE to locate the object in the catalog corresponding to the object marked on the image display with the image cursor, PEXAMINE does so by searching the data for the object whose values of xposcolumn and yposcoumn most closely match and fall within match_radius of the current cursor position.

Input to PEXAMINE is through single keystroke commands or colon commands. Keystroke commands are simple commands that may optionally use the cursor position but otherwise require no arguments. The PEXAMINE keystroke commands fall into three categories, basic commands, data examining commands and data editing commands, all described in detail in the following sections. Colon commands take an optional argument and function differently depending on the presence or absence of that argument. When the argument is absent colon commands are used to display the current value of a parameter or list of parameters. When the argument is present they change their current value to that argument. The basic colon commands are described in detail below.

BASIC KEYSTROKE COMMANDS

These keystroke commands are used to display the help page, switch from graphics to image command mode and quit the task.

?
Page through the help for the PEXAMINE task
:
Execute a PEXAMINE colon command.
g
Change to graphics command mode. Throughout PEXAMINE graphics command mode is the default. All PEXAMINE commands are available in graphics command mode.
i
Change to image command mode. All the PEXAMINE commands are available in image command mode. However if use_display is no and the image cursor has not been aliased to the standard input or a text file image command mode is disabled.
q
Quit PEXAMINE without writing an output catalog. PEXAMINE queries the user for confirmation of this option.
e
Quit PEXAMINE and write the output catalog.

DATA EXAMINING COMMANDS

The data examining commands fall into two categories, those that examine the catalog data including l (catalog listing), o (object listing), x (Y column versus X column plot) and h (histogram column plot) commands, and those which examine the image data around specific catalog objects including r (radial profile plotting), s (surface plotting), c (contour plotting) and m (pixel dumping). The latter group require that image be defined. A brief summary of each data examining command is given below.

l
Print out the name, datatype, and units for all the columns in the input catalog. The list command can be used to check the contents of the input catalog and/or determine why a particualar column was not loaded.
o
Print out the names and values of the stored columns of the object nearest the cursor. In graphics mode the current plot type must be X-Y. In image command mode the object nearest the cursor must also be no more than match-radius pixels away from the image cursor to be found. If an object is found and the current plot type is X-Y the graphics cursor is moved to the position of the selected object in the X-Y plot.
x
Plot the data in ycolumn versus the data in xcolumn excluding any already deleted points and identifying objects marked for deletion with a cross. X-Y plotting is undefined if xcolumn or ycolumn is undefined.
h
Plot the histogram of the data in hcolumn excluding any already deleted points and those marked for deletion. Histogram plotting is disabled if hcolumn is undefined.
r
Plot the radial profile of the object nearest the cursor including only pixels within a distance of rinner and router\R of the object center. Radial profile plotting is disabled if image or xposcolumn or yposcolumn is undefined.
s
Plot the surface plot of the object nearest the cursor including only pixels within an image section ncols by nlines around the object center. Surface plotting is disabled if image or xposcolumn or yposcolumn is undefined.
c
Plot the contour plot of the object nearest the cursor including only pixels within an image section ncols by nlines around the object center. Contour plotting is disabled if image or xposcolumn or yposcolumn is undefined.
m
Dump the pixel values of a grid of 10 by 10 pixels around the object nearest the cursor. Pixel value dumping is disabled if image or xposcolumn or yposcolumn is undefined.
p
Replot the current graph.

DATA EDITING COMMANDS

Data points can be deleted from the catalog in either graphics command mode or image command mode. In graphics command mode the graphics cursor and either the X-Y or histogram plot is used to delete points. In image command mode the image cursor and the displayed image are used to delete points. A data point has three possible states good, marked for deletion and deleted. Any one of the keystroke commands d (delete point), ( (delete points with x less than x cursor), ) (delete points with x greater than x cursor, ^ (delete points with y > y cursor), v (delete points with y < y cursor) or b (delete points in a box) can be used to mark points for deletion. The f key is used to actually delete the points and replot the data. In between marking the points for deletion and actually deleting the marked points the t (toggle) key can be used to undelete the last set marked. The full list of the data editing keystroke commands is given below.

z
Undelete not just unmark all the data points replot.
f
Delete points marked for deletion and replot. Points marked for deletion but not actually deleted will be written to the output catalog and not written to the deletions catalog.
d
Mark the point nearest the cursor for deletion.
u
Undelete the marked point nearest the cursor.
(
Mark all points with x values less than the x value of the cursor for deletion. In graphics command mode points can only be marked for deletion if the current plot type is "xyplot" or "histplot". In image command mode xposcolumn and yposcolumn must be defined before points can be marked for deletion.
)
Mark all points with x values greater than the x value of the cursor for deletion. In graphics command mode points can only be marked for deletion if the current plot type is "xyplot" or "histplot". In image command mode xposcolumn and yposcolumn must be defined before points can be marked for deletion.
v
Mark all points with y values less than the y value of the cursor for deletion. In graphics command mode points can only be marked for deletion if the current plot type is "xyplot". In image command mode xposcolumn and yposcolumn must be defined before points can be marked for deletion.
^
Mark all points with y values greater than the y value of the cursor for deletion. In graphics command mode points can only be marked for deletion if the current plot type is "xyplot". In image command mode xposcolumn and yposcolumn must be defined before points can be marked for deletion.
b
Mark all points within a box whose lower left and upper right hand corners are marked by the cursor for deletion. In graphics mode points can only be marked for deletion if the current plot type is "xyplot". In image command mode xposcolumn and yposcolumn must be defined before points can be marked for deletion.
t
Toggle between marking points for deletion or undeletion. The default is to mark points for deletion.

BASIC COLON COMMANDS

All the PEXAMINE parameters can be changed interactively with colon commands, including those which determine which data is read in, which data is plotted and the parameters of each plot. A brief description of the basic commands is given here. The full list is given in the following section.

:photcolumns [col1,col2,...]
Show or set the list of requested standard photometry columns and the list of loaded photometry columns. If the user supplies a new list of columns the data will be reread from disk.
:usercolumns [col1,col2,...]
Show or set the list of requested user columns and the list of loaded user columns. If the user supplies a new list of columns the data will be reread from disk.
:xcolumn [colname]
Show or set the name of the column to be plotted along the x axis of the X-Y plot.
:ycolumn [colname]
Show or set the name of the column to be plotted along the y axis of the X-Y plot.
:hcolumn [colname]
Show or set the name of the column to be whose histogram is to be plotted.
:eparam [cntrplot/histplot/radplot/surfplot/xyplot]
Review or edit the list of parameters for the various plot types.
:unlearn [cntrplot/histplot/radplot/surfplot/xyplot]
Return the list of parameters for the various plot types to their default values.
:x y key cmd
Execute any defined keystroke "key" supplying the appropriate x and y value in place of the cursor position. In graphics command mode the x and y position are assumed to be the position in the current graph. In image command mode the x and y position are assumed to be the x and y coordinate in the image display.

CURSOR COMMANDS

	PEXAMINE Interactive Cursor Keystroke Commands

                   Basic Commands

?	Print help for the PEXAMINE task
:	PEXAMINE colon commands
g	Activate the graphics cursor
i	Activate the image cursor
e	Exit PEXAMINE and save the edited catalog
q	Quit PEXAMINE and discard the edited catalog

		   Data Examining Commands

l	List the name, datatype and units for all columns in the catalog 	
o	Print out the names and values of the stored columns for the
	    object nearest the cursor
x	Replot the current y column versus the current x column
h	Replot the current histogram
r	Plot the radial profile of the object nearest the cursor
s	Plot the surface of the object nearest the cursor
c	Plot the contour plot of the object nearest the cursor
m	Print the data values of the object nearest the cursor
p	Replot the current graph

                   Data Editing Commands

z	Reinitialize the data by removing all deletions and replot
d	Mark the point nearest the cursor for deletion
u	Undelete the marked point nearest the cursor
t	Toggle between marking points for deletion or undeletion
(	Mark points with X < X (cursor) for deletion or undeletion
)	Mark points with X > X (cursor) for deletion or undeletion
v	Mark points with Y < Y (cursor) for deletion or undeletion
^	Mark points with Y > Y (cursor) for deletion or undeletion
b	Mark points inside a box for deletion or undeletion
f	Actually delete the marked points and replot


	      PEXAMINE Interactive Colon Commands

:xcolumn	  [name]	     Show/set the X-Y plot X axis quantity
:ycolumn	  [name]	     Show/set the X-Y plot Y axis quantity
:hcolumn	  [name]	     Show/set the histogram plot quantity  
:photcolumns	  [col1,col2,...]    Show/set the list of photometry columns
:usercolumns	  [col1,col2,...]    Show/set the list of user columns
:delete		  [yes/no]	     Delete or undelete points
:eparam		  [x/h/r/s/c]	     Edit/unlearn the specified plot pset
    or
:unlearn


	     PEXAMINE Interactive X-Y Plotting Commands

:x1	    [value]	  Left  world x-coord if not autoscaling
:x2 	    [value]	  Right world x-coord if not autoscaling
:y1         [value]	  Lower world y-coord if not autoscaling
:y2         [value]	  Upper world y-coord if not autoscaling
:szmarker   [value]	  Marker size
:marker [point|box|plus|cross|circle|diamond|hline|vline]    Marker type
:logx       [yes/no]	  Log scale the x axis?
:logy       [yes/no]      Log scale the y axis?
:box        [yes/no]      Draw box around periphery of window?
:ticklabels [yes/no]	  Label tick marks?
:grid       [yes/no]	  Draw grid lines at major tick marks? 
:majrx      [value]	  Number of major divisions along x axis
:minrx      [value]	  Number of minor divisions along x axis
:majry      [value]	  Number of major divisions along y axis
:minry      [value]	  Number of minor divisions along y axis
:round      [yes/no]      Round axes to nice values?
:fill       [yes/no]      Fill viewport vs enforce unity aspect ratio?


	PEXAMINE Interactive Histogram Plotting Commands

:nbins	    [value]	  Number of bins in the histogram
:z1	    [value]	  Minimum histogram intensity
:z2	    [value]	  Maximum histogram intensity
:top_closed [y/n]	  Include z in the top bin?
:x1	    [value]	  Left  world x-coord if not autoscaling
:x2	    [value]	  Right world x-coord if not autoscaling
:y1         [value]	  Lower world y-coord if not autoscaling
:y2         [value]	  Upper world y-coord if not autoscaling
:logy       [yes/no]      Log scale the y axis?
:box        [yes/no]      Draw box around periphery of window?
:ticklabels [yes/no]	  Label tick marks?
:majrx      [value]	  Number of major divisions along x axis
:minrx      [value]	  Number of minor divisions along x axis
:majry      [value]	  Number of major divisions along y axis
:minry      [value]	  Number of minor divisions along y axis
:round      [yes/no]      Round axes to nice values?
:fill       [yes/no]      Fill viewport vs enforce unity aspect ratio?

	PEXAMINE Interactive Radial Profile Plotting Commands

:rinner	    [value]	  Inner radius of the region to be plotted
:router	    [value]	  Outer radius of the region to be plotted
:x1	    [value]	  Left  world x-coord if not autoscaling
:x2 	    [value]	  Right world x-coord if not autoscaling
:y1         [value]	  Lower world y-coord if not autoscaling
:y2         [value]	  Upper world y-coord if not autoscaling
:szmarker   [value]	  Marker size
:marker [point|box|plus|cross|circle|diamond|hline|vline]    Marker type
:logx       [yes/no]	  Log scale the x axis?
:logy       [yes/no]      Log scale the y axis?
:box        [yes/no]      Draw box around periphery of window?
:ticklabels [yes/no]	  Label tick marks?
:grid       [yes/no]	  Draw grid lines at major tick marks? 
:majrx      [value]	  Number of major divisions along x axis
:minrx      [value]	  Number of minor divisions along x axis
:majry      [value]	  Number of major divisions along y axis
:minry      [value]	  Number of minor divisions along y axis
:round      [yes/no]      Round axes to nice values?
:fill       [yes/no]      Fill viewport vs enforce unity aspect ratio?


	PEXAMINE Interactive Surface Plotting Commands

:ncolumns   [value]	  Number of columns to be plotted
:nlines	    [value]	  Number of lines to be plotted
:axes	    [yes/no]	  Draw axes?
:angh	    [value]	  Horizontal viewing angle
:angv	    [value]	  Vertical viewing angle
:floor	    [value]	  Minimum value to be plotted
:ceiling    [value]	  Maximum value to be plotted


	PEXAMINE Interactive Contour Plotting Commands

:ncolumns   [value]	  Number of columns to be plotted
:nlines	    [value]	  Number of lines to be plotted
:floor	    [value]	  Minimum value to be plotted
:ceiling    [value]	  Maximum value to be plotted
:zero	    [value]       Greyscale value of zero contour
:ncontours   [value]	  Number of contours to be drawn
:interval    [value]       Contour interval
:nhi	    [value]       Hi/low marking option
:dashpat     [value]       Bit pattern for generating dashed lines
:label       [yes/no]      Label major contours with their values?
:box        [yes/no]      Draw box around periphery of window?
:ticklabels [yes/no]	  Label tick marks?
:majrx      [value]	  Number of major divisions along x axis
:minrx      [value]	  Number of minor divisions along x axis
:majry      [value]	  Number of major divisions along y axis
:minry      [value]	  Number of minor divisions along y axis
:round      [yes/no]      Round axes to nice values?
:fill       [yes/no]      Fill viewport vs enforce unity aspect ratio?

EXAMPLES

1. Examine and edit an APPHOT aperture photometry catalog and a DAOPHOT allstar catalog without either attaching the associated image or using the image display.

    pt> pexamine m92.mag.1 m92.mag.ed use_display-

	... a plot of magnitude error versus magnitude appears on
	    the screen and the graphics cursor comes up ready to accept
	    commands

	... the user sees a generally smooth trend of increasing
	    magnitude error with increasing magnitude except for a
	    single deviant point at the bright end of the plot

	... the user decides to remove the deviant point using the
	    'd' keystroke command to mark the point and the 'f'
	    keystroke command to actually delete and replot the graph

	... after examining the plot further the user decides to delete
	    all objects for which the magnitude error is > 0.1 magnitudes
	    using the '^' keystroke command, followed by the 'f'
	    keystroke command to actually replot and delete the data.

	... after deciding that this new plot is satisfactory the user
	    issues the 'e' keystroke command to exit pexamine and save
	    the good data in m92.mag.ed

    pt> pexamine m92.als.1 m92.als.ed use_display-

	... a plot of magnitude error versus magnitude appears on the
	    screean and the graphics cursor comes up ready to accept
	    commands

	... after looking at the plot the user decides that what they
	    really want to see is a plot of the goodness of fit parameter
	    chi versus magnitude

	... the user issues the colon command :ycol chi followed by 'p'
	    keystroke command to replot the data

	... the user sees a generally smooth trend of increasing
	    chi with increasing magnitude 

	... after examining the plot further the user decides to delete
	    all objects for which the chi value  > 2.0  and the
	    magnitude is > 25 using the '^' key and ')' keystroke
	    commands followed by 'f' to save the deletions and replot
	    the data

	... after deciding that this new plot is satisfactory the user
	    issues the 'e' keystroke command to exit pexamine and save
	    the good data in m92.als.ed

2. Examine and edit a DAOPHOT allstar catalog using the subracted image, the original image and the image display.

	pt> display image.sub 1

	    ... display the subtracted image

	pt> pexamine orionk.als.1 orionk.als.ed image xcol=mag ycol=chi

	... a plot of the goodness of fit versus magnitude appears
	    on the terminal and the graphics cursor comes up ready to
	    accept commands

	... the user notices some very anomalous chi values and decides
	    to see if these correspond to objects which have poor
	    subtraction on the displayed image

	... the user switches to image command mode by tapping the 'i'
	    key, moves to the first poorly subtracted object and taps
	    the 'o' key

	... a list of the values of the loaded columns including chi
	    appears in the text window , the program switchs to graphics
	    mode and places the graphics cursor on the corresponding
	    point in the X-Y plot

	... the point in question indeed has a very high chi value
	    and the user decides to try and investigate the reason for the
	    anomalous value

	... the user taps the 'r' key to get a radial profile of the
	    object in the original image

	... after carefully examining the profile it appears that the
	    object's profile is too broad and that it is not a star

	... the user switches back to the X-Y plot with the 'x' key,
	    marks the point with the 'd' key and saves the deletions
	    and replots with the 'f' key.

	... the user goes back to image command mode with the 'i' key
	    and begins investigating the next object

	... finally after examining the image and making all the changes
	    the user decides to quit and save the changes with the 'e' key

TIME REQUIREMENTS

BUGS

If the display device is on a remote resource the first image cursor request will cause PEXAMINE to hang. The remote resource is expecting the appropriate password which the user must type in to cause the the image cursor to appear. The normal password prompt is not being issued or flushed to the terminal. The solution to the problem is to put the password in the .irafhosts file

INDEF valued points cannot be accessed by PEXAMINE. INDEF valued points should be removed from the input catalog with SELECT prior to entering PEXAMINE.

SEE ALSO

ptools.select, ptools.txselect,ptools.tselect


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