Last Updated Jan 2001

Copyright © 2001 The Association of Universities for Research in Astronomy, Inc. All Rights Reserved.

Purpose :

Procedure :

Position of the maximum out of x_boxsize or y_boxsize defined from cim image. (This happen if the cutout was runned in a big object and the cutout take only a part of it)

Classification code defferent from that specified with the option /CLASS_TYPE=a.

Dimension of the cutout bigger than max_size, where max_size is 512x512 matrix.

centroider_params(1)=(image_max-bzero)/bscale !amplitude of gaussian

centroider_params(2)=oop.x_position-cih.lx+1.5 !x position on the cutout

centroider_params(3)=oop.y_position-cih.ly+1.5 !y position on the cutout

Circular Gaussian

number_parameters=7

centroider_params(4)=sqrt((oop.uf_xx+oop.uf_yy)/2.0) !sigma of circular gaussian

Elliptical Gaussian

number_parameters=9

centroider_params(4)=sqrt(oop.uf_xx) !sigma_x of ellipltical gaussian

centroider_params(5)=sqrt(oop.uf_yy) !sigma_y of ellipltical gaussian

centroider_params(6)=oop.uf_xy /(sqrt(oop.uf_xx)*sqrt(oop.uf_yy)) !Correlation coefficent

ENDIF

centroider_params(number_parameters-2)=0.001 !background plane x coefficient

centroider_params(number_parameters-1)=0.001 !background plane y coefficient

centroider_params(number_parameters-0)=(skyc-bzero)/bscale !background plane constant

Number of iterations > centroider_option(1) (=NUM_IT_MAX)

[In this case centroider_error=-1]

Difference on the parameters (step i+1 - step i)

[In this case centroider_error=see Output Effects]

Output Effects :

Calling Sequence :

CENTROIDER_SINGLE imagefile

[/XRANGE=(lx,ux)]

{default entire plate}

[/YRANGE=(lx,ux)]

{default entire plate}

[/CLASS_TYPE=n] Type of object where run the Centroider {def=1}

{def = 0 --> Stars}

{ 1 --> Galaxies}

[/ALL_CLASS] Run the centroider on all objects, don't take in account the qualifier /CLASS_TYPE=n

{def = False}

[/CENT_TYPE=a] Type of centroider

{def=CIRCULAR}

CIRCULAR ----> Circular Gaussian + slanting plane as local background

ELLIPTICAL --> Elliptical Gaussian + slating plane as local background

[/NUM_IT_MAX=n] Max. number of iterations

{default = 30}

[/ERR_TOLL=t.] Max. differences on the parameters computed at (step i+1 - step i) multiplied for 1000

{default 0.001}

[/CEN] Write output to cen file (same structure as the oop file)

{defaults doesn't write on cen, upgrade the oop}

[/NO_ERR_FILE] Don't write the oop.object_number, oop.cih_id and flag centroider for the object where the centroider fails.

{default write on the file ****.centr_error with this format='(2x,i8,2x,i8,2x,i2)' oop.object_number,oop.cih_id,centroider_flag}

[/VERBOSE]

[/DEBUG] Debug mode

Availability :

• GSSS AXP - yes
• GSSS VAX - yes
• PIXELS - no

History/Author :