or aperture corrections files for a given image set file.
mkphotcors imsets idfilters obsparams shifts apercors
imsets
The name of the input/output text file of observations, where a complete
observation consists of an observation name usually the name of
the observed star field,
followed by a list of images of that star field taken through the filters
idfilters.
If imsets does not exist, MKPHOTCORS prompts the user for
input and writes the results to a new image set file imsets.
If imsets does exist, MKPHOTCORS reads the file and prints messages
about any errors or inconsistencies it finds in it. If imsets is "",
MKPHOTCORS prompts the user for input, but does not create a new imsets
file.
idfilters
The list of filters separated by whitespace or commas which define a complete
observation. If imsets is entered interactively by the user,
idfilters defines the number of images in an
observation. If imsets is an existing file, MKPHOTCORS uses
the number of filters specified by idfilters to
check that there are the correct number of images in each observation.
obsparams
The name of the input/output text file containing the quantities filter id,
exposure time, airmass, and time of observation, for each image in imsets.
If obsparams does not exist, MKPHOTCORS prompts the user for input
and writes the results to the new observing parameters file obsparams.
If obsparams already exists, MKPHOTCORS reads the file using the format
specified by obscolumns, and prints out messages about any
errors and inconsistencies it finds.
If obsparams
is "", the user is not prompted for input and no output file is created.
shifts
The name of the input/output text file containing the x-y shifts to be applied
to the measured x-y coordinates of each object in each image in imsets.
If shifts does not exist, MKPHOTCORS prompts the user for input
and writes the results to the new shifts file shifts.
If shifts already exists, MKPHOTCORS reads the file and prints out
messages about any errors and inconsistencies it finds.
If shifts is "", the user is not prompted for input and no output
file is created.
apercors
The name of the input/output text file containing the aperture corrections
to be applied
to the measured magnitudes of each object in each image in imsets.
If apercors does not exist, MKPHOTCORS prompts the user for input
and writes the results to the new aperture corrections file apercors.
If apercors already exists, MKPHOTCORS reads the file and prints out
messages about any errors and inconsistencies it finds.
If apercors is "", the user is not prompted for input and no output
file is created.
obscolumns = 2 3 4 5
The list of numbers separated by commas or whitespace specifying which
columns in obsparams contain the filter ids, exposure times,
airmasses, and times of observation, respectively of the images listed in column 1.
Obscolumns is only used if obsparams already exists on disk.
The number 0 may be used as a place holder in the obscolumns string.
For example to read in only the airmass values, obscolumns should be
set to "0 0 column" if the airmass values are in column.
verify = no
Verify all data entered interactively ?
verbose = yes
Print messages about actions taken by MKPHOTCORS, and any warning or error
messages generated.
MKPHOTCORS takes an image set file imsets and a list of filter ids idfilters and writes one or more of the photometric corrections files obsparams, shifts and apercors required by the preprocessor tasks MKNOBSFILE and MKOBSFILE. MKPHOTCORS is intended as a simple tool to assist the user in creating and/or checking the input required by the MKNOBSFILE and MKOBSFILE tasks.
Imsets is the name of the input/output text file which tells MKNOBSFILE or MKOBSFILE which observations are to be extracted from the photometry files. A complete observation consists of the observation name, for example "M92", followed by a list of images taken through the filters idfilters, for example "m92u m92b m92v". Observations are listed in imsets, 1 observation per line, with the observation name in column 1, a colon in column 2, followed by, in filter order and separated by whitespace, the names of the images belonging to that observation. A sample image set file is shown in the next section.
Imsets may be an existing file created with the MKIMSETS task, a file typed in by hand by the user, or a new file to be created by MKPHOTCORS. If imsets already exists, MKPHOTCORS reads the file and prints warning messages if it cannot decode the observations specification, or if the number of images in the observation does not match the number specified by idfilters. If imsets does not exist, MKPHOTCORS prompts the user for input using idfilters to determine the number of images there should be in each observation, and writes the results to the new image set file imsets. If imsets is "", MKPHOTCORS prompts the user for input but does not save the results.
Obsparams is the name of the input/output text file listing the observng parameters filter id, exposure time, airmass, and time of observation, for the images in imsets. Obsparams is used to correct missing or incorrect filter ids, exposure times, airmasses, and times of observation in the photometry files, and is not required if all these values are correctly recorded in the photometry files. The observing parameters for each image are listed in obsparams, 1 image per line, with the image name in column 1, and the filter id, exposure time, airmass, and time of observation in the columns obscolumns. A sample observing parameters file is shown in the next section.
Obsparams may be an existing file created with the MKIMSETS task, a file typed in by hand by the user, or a new file to be created by MKPHOTCORS. If obsparams already exists, MKPHOTCORS reads the file and prints warning messages if it cannot decode the observing parameters, or if the there is an entry which does not correspond to one of the images listed in imsets. If obsparams does not exist, MKPHOTCORS prompts the user for input for each image in imsets and writes the results to a new observing parameters file obsparams. If obsparams is "", MKPHOTCORS does not prompt for input and no new file is written.
Shifts is the name of the text file specifying the x-y shifts, as a function of image, to be added to the x-y positions of all objects in the images listed in imsets. These shifts are used to brings frames of the same star field taken through different filters into rough alignment before matching individual objects. Shifts is not required if the frame to frame shifts are small, as is usually the case if the filters are of comparable thickness, and the exposures are short or well-guided. The x-y shifts are listed 1 per line with the name of the image in column 1, and the x and y shifts in columns 2 and 3 respectively. A sample shifts file is shown in the next section.
Shifts may be an existing file created with the IMCENTROID task and edited by the user, a file typed in by hand by the user, or a new file to be created by MKPHOTCORS. If shifts already exists, MKPHOTCORS reads the file and prints warning messages if it cannot decode the shifts, or if the there is an entry which does not correspond to one of the images listed in imsets. If shifts does not exist, MKPHOTCORS prompts the user for input for each of the images in imsets and writes the results to a new shifts file shifts. If shifts is "", MKPHOTCORS does not prompt for input and no new file is written.
Apercors is the name of the text file specifying the aperture corrections, as a function of image, to be added to the magnitudes of all objects in the images listed in imsets. The aperture corrections are most often used to correct the instrumental magnitudes of stars measured through a small aperture to minimize crowding affects, to the instrumental magnitudes of standard stars measured through a larger aperture. These aperture corrections will normally be a function of filter and of seeing and focus which can change throughout the night. Aperture corrections are normally not required for standard star measurements. Aperture corrections are listed 1 per line with the name of the image in column 1, and the aperture correction in column 2. A sample aperture corrections file is shown in the next section.
Apercors may be an existing file typed in by hand by the user, or a new file to be created by MKPHOTCORS. If apercors already exists, MKPHOTCORS reads the file and prints warning messages if it cannot decode the aperture corrections, or if the there is an entry which does not correspond to one of the images listed in imsets. If apercors does not exist, MKPHOTCORS prompts the user for input for each of the images in imsets and writes the results to a aperture corrections file apercors. If apercors is "", MKPHOTCORS does not prompt for input and no new file is written.
A sample image set file for a set of UBV 100 second, 600 seconds, and 1800 second exposure images of the globular cluster m92 is shown below. The labels "M92S", "M92M", and "M92L" stand for the 100, 600, 1800 second exposure observations sets respectively. The names which follow the labels are the names of the actual IRAF images comprising each data set. The image names must match those in the photometry files.
M92S : m92us m92bs m92vs M92M : m92um m92bm m92vm M92L : m92ul m92bl m92vl
A sample observing parameters file is shown for the above data set. In this example the user forgot to tell the photometry code to pick up the filter ids, exposure times, airmasses, and times of observation from the image headers and so is obliged to correct them after the fact via the observing parameters file. The filters U B V are represented by the numbers 1 2 3.
m92us 1 100 1.10 03:10:53 m92bs 2 100 1.09 03:14:06 m92vs 3 100 1.06 03:18:54 m92um 1 600 1.03 04:15:05 m92bm 2 600 1.03 04:29:43 m92vm 3 600 1.03 04:44:56 m92ul 1 1800 1.06 06:10:33 m92bl 2 1800 1.12 06:45:32 m92vl 3 1800 1.18 07:23:02
A sample shifts file for the above data set is shown below. Only the long exposure frames have significant frame to frame shifts so only those images are included in the shifts file. The long u frame is used a position reference so its x-y shift is zero.
m92ul 0.0 0.0 m92bl 5.4 8.4 m92vl 9.6 17.1
A sample aperture corrections file for the above data set is shown below. Note that the aperture correction appears to vary in a systematic way with filter.
m92us -.153 m92bs -.110 m92vs -.083 m92um -.149 m92bm -.108 m92vm -.090 m92ul -.160 m92bl -.123 m92vl -.079
1. Type in the image set file and accompanying shifts and aperture corrections files for a set of UBV observations of a crowded field in NGC4147. The filter ids "1 2 3" stand for "U B V". The photometry programs picked up the correct values of the filter id, exposure time, and airmass from the image headers and wrote them to the photometry files so the observing parameters file is not required.
ph> mkphotcors n4147.imsets "1,2,3" "" n4147.shifts n4147.apcors
2. Type in the shifts and aperture corrections files for the already existing image set file m17.imsets. In this case the filter set is "J H K".
ph> mkphotcors m17.imsets "J,H,K" "" m17.shifts m17.apcors
TIME REQUIREMENTS
mkimsets, mknobsfile, mkobsfile,