NAME

parthitf -- Remove particle events from FGS photomultiplier counts.

USAGE

parthitf infile inmask outtable sigma0 sigma threshold hitval inttime

DESCRIPTION

Data in groups PMTXA, PMTXB, PMTYA, and PMTYB are photomultiplier (PMT) counts from the Fine Guidance Sensor (FGS). Parthitf will remove particle events, that is, pixels of high counts, from PMT groups.

Mean and standard deviations are calculated for all points in a group having values higher than that of threshold. If a pixel value is higher than the mean by sigma0 times the standard deviation, it is considered to be a particle event, and will be assigned the value of hitval. After the first round of removals, mean and standard deviations are recalculated using the remaining points--particle events are again located using these new values. This process continues until no more points are removed. Statistics about particle events are calculated and put in the output table.

The program produces an output table with the following columns:

COLUMN NAME			CONTENTS
-----------			--------
OBSID				Observation ID

ASTMODE				FGS observation mode

FGSID				FGS ID number

PMTXA_NOHIT, PMTXB_NOHIT,	Number of particle events in each PMT
PMTYA_NOHIT, PMTYB_NOHIT

PMTXA, PMTXB, PMTYA, PMTYB	Mean counts in each PMT after particle
				count removal

PMTXA_STD, PMTXB_STD,		Standard deviations of each PMT after 
PMTYA_STD, PMTYB_STD		particle count removal

PMTXA_HIT, PMTXB_HIT,		Mean counts of particle counts in each PMT
PMTYA_HIT, PMTYB_HIT

PMTXA_HITF, PMTXB_HITF,		Particle event frequencies in each PMT 
PMTYA_HITF, PMTYB_HITF		(per second)

ANGLE_A, ANGLE_B		Mean values of theta A and B angles, i.e., 
				average of 'SSENCA' and 'SSENCB'

STD_A, STD_B			Standard deviation of theta A and B angles

SIGMA0				Statistical criterion of particle event
				removal in first iteration

SIGMA				Statistical criterion of particle event
				removal in subsequent iterations

PARAMETERS

infile [file name template]

Name of the FGS data file from which particle events are to be removed.

inmask [file name template]

Name of file containing the data quality mask to be used. (Masks are generated by the dqmgen task).

outtable [file name]

The output table produced by parthitf.

sigma= 3.0 [real, min = 0]

Statistical criterion for removing a particle event in the task's first iteration.

sigma = 3.[real, min = 0]

Statistical criterion for removing particle events during subsequent iterations.

threshold = 0.[real]

Lowest possible value of good points. Points whose mask values are below this level will be neglected in the calculation.

hitval = 0.[real]

Mask value to be assigned to the particle event pixels.

(inttime = 0.025) [real, min = 0]

Integration time of each pixel, in seconds.

EXAMPLES

1. Remove particle events for input files yparthitf$infile.d1h and yparthitf$infile.d2h with corresponding mask files yparthitf$inmask.m1h and yparthitf$inmask.m2h. Write results to the table xparthitf$output.tab. Points that are 2.5 standard deviations above average will be regarded as particle events during the first iteration (3 standard deviations above average in subsequent iterations). Neglect points with mask value below 0.5. Integration time is 25 milliseconds (the default value) in each pixel, and the mask value 0 will be assigned to the particle event pixels:

fg> parthitf (infile = "yparthitf$infile.d![1-2]h", \
>>> inmask = "yparthitf$inmask.m![1-2]h", \
>>> outtable = "xparthitf$output", sigma0 = 2.5, sigma = 3, \
>>  threshold = 0.5, hitval = 0, inttime = 0.025)

BUGS

SEE ALSO