MOPEX Online Manual

APEX User List

APEX User List Multiframe (apex_user_list.pl)

APEX allows the user to input positions of objects instead of using the current Detect module. However the code is still experimental. With some limitations discussed below, APEX will do PRF fitting and aperture photometry on the input list. With the normal "apex_user_list" namelists, the positions of objects will be allowed to move within a small radius as part of the fitting. PRF-fitted and aperture fluxes will be for that (possibly shifted) position. Note also that APEX will not search for additional objects, so if any are missing then proper deblending cannot be done.

In User List mode, the user's input table becomes the detection list. This is set by the keyword "INPUT_USER_LIST = user.tbl" in the namelist, or the command-line option "-u" followed by the table in a command-line call to the Perl script. A command-line entry takes precedence.

Other changes include a variable called "use_input_list_type". This indicates the coordinates of the input list. There are also new optional parameters in the sourcestimate block: ANGULAR_DIST, and MAX_SHIFT_X, MAX_SHIFT_Y.

Nearby sources for each input source are determined and fitted together in the sourcestimate module using the given ANGULAR_DIST (arcsec). Positions will move to "best-fit" values. Sources which are successfully fit but drift outside MAX_SHIFT_X, MAX_SHIFT_Y data pixels from the input position are flagged in the output table. The format of the output extract table is otherwise the same as before.

In User List mode, the parameters Fitting_Area_X and Fitting_Area_Y (data pixels) which let the user define the fitting region are *required*.

There are two more parameters MAX_SHIFT_X and MAX_SHIFT_Y (data pixels). If the fitted source position is greater than Max Shift away from the user-supplied position, the source is given a letter "O" in the deblend column (for "Outside"), along with any other letter flags. By default, these parameters are set equal to the fitting area dimensions. Typically, namelists will have a "select" condition that drops a source with an "O" in the deblend column.

For multi-frame Apex in User List mode, creation of a detection map is required: run_detectionmap = 1. This creates "detectionmap.tbl" in the output directory. Once it is created, this can be turned off for subsequent runs. Also note that in this case the "InputType" parameter in the sourcestimate block should be set to "detection_map". These steps are needed to track the input source positions through the image stack.

In the Apex namelists, both detect_medfilter and gaussnoise should be turned on to provide the ability to use background RMS for the point-source SNR.

The input source positions are sorted first in Dec in ascending order. Bins are created in this sorted list using bin size = 2 * ANGULAR_DIST. The sources are again sorted in RA within each bin. Each input source position is then searched to find its distance from the other sources in the current bin and 2 adjacent bins on both sides. If this distance < ANGULAR_DIST, then the source is flagged as a nearby source and included in the fitting.

APEX User List Single Frame (apex_user_list_1frame.pl)

For single frame mode, the point source extraction is carried out as above, only this time it is carried out on the mosaic rather than the stack of BCDs.

APERTURE PHOTOMETRY ON FIXED POSITIONS: This can be done in Single Frame mode on mosaics by using the namelists provided in the cdf directory with the "aponly_fixed" in them.

Running APEX User List

APEX User List Multiframe

APEX User List Multiframe is run on the command line using the perl wrapper script apex_user_list.pl. The syntax is as follows:

prompt> apex_user_list.pl <option flag> <specification>

where <option flag> can be any of the flags for APEX Multiframe, plus the following extra input:

Input_User_List
Called from the command line with the option -u. The input table of source positions has to be in IPAC table format. A minimum of two data columns are required. Positions may be entered in sky coordinates, which are labeled with column names ("RA", "Dec"). These should have type "double" (d). This is the simplest way. Positions can be in pixel coordinates which are labeled with column names ("X","Y"), or by ("Global_X", "Global_Y"). In multi-frame mode, this is pixel position on the mosaic. These should have type "real" (r). The table may contain both sets of coordinates and other data columns.

Example Input User List:

|RA        |Dec        |
|d         |d          |
 41.53471   -30.38459
 41.54912   -30.34542  



Users must also set the following switch in their namelist:

use_input_list_type
Namelist parameter switch telling MOPEX whether the User Input List coordinates are in RA and Dec or pixel coordinates. Possible values = 0, 1. A value of 1 indicates that the Input User List gives the source positions in RA, Dec with column names ("RA", "Dec"). The conversion program "s2c_trans" is used to convert the sky coordinates into pixel positions. A value of 0 (the default) indicates pixel positions. In multi-frame mode, this is the pixel position on the mosaic. The column names in the input file are ("X","Y"). The conversion program "c2s_trans" is used to convert the pixel positions into sky coordinates. A value > 1 indicates that both types exist in the input table. Column names can be either ([X, Y], [RA, Dec]) or ([Global_X, Global_Y], [RA, Dec]).

APEX User List Single Frame

APEX User List Single Frame is run on the command line using the perl wrapper script apex_user_list_1frame.pl. The syntax is as follows:

prompt> apex_user_list_1frame.pl <option flag> <specification>

where <option flag> can be any of the flags for APEX Single Frame, plus the extra input listed above in the APEX User List Multiframe section.





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