SEE_ALSO

## NAME

smaperloc -- Small aperture location calibration, phase III.

## USAGE

`smaperloc intable outtable contourkeep contourtable edge_level`

## DESCRIPTION

This task will use the data in a grid of different pointings to
determine the edge contour
of the circular aperture, and will then use these contour edge data to fit a
circle---locating the center coordinates in the V2,V3 coordinate system.
The highest 10% of all data points are used to determine the average maximum
count. The edge count level is then determined from this average count
multiplied by a fraction that the user specifies with the `edge_level`
parameter. The coordinates of the
edge points can be written to a table. A least squares method is then used to
calculate the circle center and the radius of the aperture.

The input table can not have more than 2,500 points.

## PARAMETERS

- intable [file name]
- Name of the input table; this table has the following columns:
'DOBJ' Digital count rate (real). 'DOBJ_ERR' Standard deviation of 'DOBJ' (real). 'V2' V2 coordinate of the pointing (real). 'V3' V3 coordinate of the pointing (real). 'EPOCH' Epoch of the observation (double).

- outtable [file name]
- File name for the output table created by
`smaperloc`; this table will have the following columns:'V2' V2 coordinate of the aperture center (real). 'V3' V3 coordinate of the aperture center (real). 'RADIUS' Radius of the circle (real). 'SIGMA_V2' Standard error of 'V2' (real). 'SIGMA_V3' Standard error of 'V3' (real). 'SIGMA_RADIUS' Standard error of 'RADIUS' (real). 'CORR_V2_V3' Correlation between 'V2' and 'V3' (real). 'CORR_V2_R' Correlation between 'V2' and 'RADIUS' (real). 'CORR_V3_R' Correlation between 'V3' and 'RADIUS' (real). 'V2_WEIGHT' Weight scheme of 'V2' (real). 'V3_WEIGHT' Weight scheme of 'V3' (real). 'CHISQ' Chi-squared (real). 'TOLERANCE' Convergence of sigma squared (real). 'FRACTION' Specified fraction applied to the coefficient modification during the least squares fitting (real). 'NPOINTS' Number of input data points (int). 'ITERMAX' Number of iterations used in the least squares fitting (int).

- contourkeep = no [boolean]
- Keep the table containing edge coordinates?
If

`countourkeep`is set to "yes", a file name must be specified in the`contourtable`parameter.

- contourtable [file name]
- if
`countourkeep = yes`, then this parameter contains the file name of the table where the edge contour points' coordinates are stored. The contour table has the following columns:(v2name) 'V2' coordinate (real). (v3name) 'V3' coordinate (real). (dv2name) Standard error of V2 (real). (dv3name) Standard error of V3 (real).

- edge_level = 0.[real, min = 0., 1.]
- Fraction of the average maximum count to be used to specify the edge count level.

- (v2_key = "V2") [string]
- Column name of the V2 coordinate in the input table.

- (v3_key = "V3") [string]
- Column name of the V3 coordinate in the input table.

- (count_key = "DOBJ") [string]
- Column name of the count rate in the input table.

- (counterr_key = "DOBJ_ERR") [string]
- Column name of the count rate's standard deviation in the input table.

- (v2weight = -2.) [real]
- Weighting flag of the V2 coordinate. The weight of each data point is
proportional to the standard deviation with this flag as its exponent.
For example, if
`v2weight = 0`, equal weights is applied and if 'v2weight = -1000' or less, V2 coordinates are assumed to be exactly precise.

- (v3weight = -2.) [real]
- Weighting flag of the V3 coordinate. The weight of each data point is
proportional to the standard deviation with this flag as its exponent.
For example, if
`v3weight = 0`, equal weights is applied. We can not set BOTH`v2weight`and`v3weight`to -1000 or less.

- (itermax = 100) [integer, min = 1]
- Maximum number of iterations to be used in the non-linear least squares fitting.

- (tolern = 1.E-12) [real, min = 0., max = 1.]
- Tolerance in determining the "goodness" of the least squares fit. If the
FRACTIONAL improvement of the sigma-squared is smaller than
`tolern`, the fit is deemed satisfactory and the least squares iteration will terminate.

- (frac = 0.5) [real, min = 0., 1.]
- Specified fraction applied to the coefficients modification during the non-linear least squares fitting.

- (v2name = "V2") [string]
- Column name of the V2 coordinate in the contour table.

- (v3name = "V3") [string]
- Column name of the V3 coordinate in the contour table.

- (dv2name = "DV2") [string]
- Column name of V2 coordinate's error in the contour table.

- (dv3name = "DV3") [string]
- Column name of V3 coordinate's error in the contour table.

## EXAMPLES

1. Calculate the aperture center from the input data table `xsmaperloc$input`,
putting results in the output table `ysmaperloc$output` and saving the contour
coordinates in another table called `ysmaperloc$contour`. The edge count
rate is
half of the average of the top 10% points. Both axes are equally weighted.
Digital data is used.

hs> smaperloc "xsmaperloc$input" "ysmaperloc$output" yes "ysmaperloc$contour" 0.5 count_key="DOBJ" counterr_key="DOBJ_ERR" v2weight=-2 v3weight=-2

## BUGS

## REFERENCES

## SEE ALSO