Init, Status, Script and Coord Files

1. Init Files

The init files live in directory Hydra/data/inits. There are four of them: astroparams, concentricities, limitparams and systemparams.

1.1 astroparams

This file defines several important constants and values for doing astrometry calculations. The list below shows the names and a a short description for each of the included values.

CTIO_LAT - Obserbatory Latitude : -30.16542

CTIO_ALT - Height of the observatory: 2200 m

CTIO_ATM_PRESS - Typical atmospheric pressure in milibars

LAPSE_RATE - Temperature lapse rate in the troposphere (degK/meter)

POLAR_FLAG - Activate polar misalignment corrections

ME, MA - Polar misalignment correction parameters

REFRACT_PREC - Refraction calculation precission

REFRACT_PTS - Number of refractions points.

TEMP_MONTH - Comma separated list with average nightime temperatures for each moth

FOCALLEN - Focal length in mm

D3 - Parameter d3 of the optic correction model

D5 - Parameter d5 of the optic correction model

CTIO_SCALE - Plate scale in arcsec/mm

CTIO_RADIUS - Radius of curvature (mm) of focal surface located 6 mm above mid-plate radius

CTIO_WARP_DISTANCE - Border to decide waht curve to use when applying warp model (mm)

CTIO_INNERMID_RADIUS - Radius of the mid-plate in mm (measured plate radius plus thickness devided by two) for inner warp model

CTIO_OUTERMID_RADIUS - Radius of the mid-plate in mm for outer warp model

UNWARP_A1 - First coefficient to the model for unwarping the plate

UNWARP_A2 - Second coefficient to the model for unwarping the plate

ENCODER_SCALE - Encoder steps per mm of travel: 1 step/mm

DEFAULT_WAVECAM - Default wave length: 6000 A

ROT_CORRECTION - Rotational mis-alignment correction

 

1.2 concentricities

This file contains the cable and fiber definitions. The format for a cable definition is a line containing 5 fields. The first field is the cable identifier consisting of one upper case character. The second field is the cable label. It is a character, either 'A' or 'N'. It affects references to slit position inquiries. 'A' means that fibers are identified with alpha characters (A-Z, limit of 26 fibers in cable). 'N' means that integers are used to reference them. For alpha references a slit position of 1 maps to 'A', 2 maps to 'B', etc. The third field is a character 'Y' or 'N' saying if this cable can be selected. The fourth field isthe cable name, consisting of a string with no spaces and case insensitive. Finally, the fifth field is a short description of the cable been defined.

NOTE: a cable doesn't exists if it's not listed in this file.

The format for a fiber definition is a line containing six fields. The first field is the fiber number on plate represented by an integer and beginning from zero. The second field is a positive integer representing the slit position for that fiber. The third field is a single character saying to which cable this fiber belongs to. The fourth field is a single character flag stating the status of this fiber: 'A' for active fiber, 'B' for broken fiber, 'L' for locked fiber and 'Z' for noexistant fiber. The fifth field is a floating point number in encoder units representing the concentricity offset of the fiber. The sixth field is a floating point number in radians representing the concentricity angle.

The concentricity offset and angle data can be measured at any time as described in chapter Measuring Concentricities.

The latest concentricities files are available here:

• alternating_concentricities --for use with the Air Schmidt camera.
• concentricities --for use with the 400m Bench Schmidt camera.

 

1.3 limitparams

This file contains the data for the initialization of the data structures that are used in testing for limit conditions.

 

1.4 systemparams

This file include instrument specific parameters like the plate radii, button diameter, tube diameter,etc. It also includes the mechanical correction parameters (coefficients to the mechanical model of the positioner). The list below describes some of the constants declared in this file.

PLATE Plate radius in microns

STOW Radius of the fiducial stow position circle in microns

PARK Radius of the park position circle in microns

PIVOT Radius of the fiber pivot in microns

STOWSLOP Not used

STOWOFFSET Offset added to the stow position angle of a fiber when the x/y stow position is calculated.

MAXANGLE Is the max angle in radians for flexing a fiber without overstressing it.

ANGLE_SOFTNESS Offset in radians added to MAXANGLE before checking for overflexure.

PARKEDATRISK Not used

BUTTONHEIGHT Not used

GRABHEIGHT Not used

BUTTONDIA Diameter of a button in microns

TUBEDIA Diameter of a tube in microns

BUTTON_TUBE_MARGIN Offset for interactions between a tube and a button

BUTTON_BUTTON_MARGIN Offset for interactions between two buttons.

REQPREC Not used

CRITICALANGLE Not used

MAXFORPRECALC Constant used in fiber to button distance calculations.

THERM_COEF Thermal expansion coefficient (K^-1)

TZERO Thermal expansion zero point (Celcius degrees)

XSCALE_ADJUST, YSCALE_ADJUST, DXY_LINEAR, DYX_LINEAR,DXY_QUAD, DYY_QUAD. Stage distorsion correction constants. Units in terms of encoder steps.

FDXX_LINEAR, FDYY_LINEAR, FDXX_QUAD, FDYY_QUAD Constants used to do final tweaking of positional error; units interms of encoder steps.

XH_LINEAR, XH_QUAD, XD_LINEAR, XD_QUAD, YH_LINEAR, YH_QUAD, YD_LINEAR, YD_QUAD. Constants used in flexure calculations. X-Y Gravitational terms

COMPLAMP_TIMEOUT Timeout when waiting for comparison lamps to complete motion.

 

2. Status Files

 

3. Script Files

A set of scripts are available for doing repetitive job automatically. Things like parking all the fibers of one type or configuring the fibers in a circle type pattern are easily made by executing script files. The script files are kept at "ctioa6:/home/hercules/Hydra/data/scripts". You can either use the execfile cli command or use the "File/Run Script..." menu option to source a script file.

viewlarge, viewsmall, viewfops - Use these scripts to take a look at the fibers by type. Hydra CTIO has three type of fibers installed: LARGE, SMALL and FOPS. The gripper will go fiber after fiber waiting exactly one second before moving to the next one. For example to view the FOPS fibers type at the CLI/Script Tool command line:

Fiborg3.2.0> execfile viewfops

parklarge, parksmall, parkfops - Use these scripts to park the fibers by type. For example to park the large fibers type at the CLI/Script Tool command line:

Fiborg3.2.0> execfile parklarge

configparklarge, configparksmall, configparkfops - Use these scripts to park the fibers by type. This scripts use the configure -c commad to execute "parklarge", "parksmall" and "parkfops" saving time by doing an "intelligent" transition from the current configuration to park position.

largecircle, smallcircle, fopscircle - These scripts put the fiber in a circle.

configlargecircle, configsmallcircle, configfopscircle - These scripts put the fiber in a circle. This scripts use the configure -c commad to execute "largecircle", "smallcircle" and "fopscircle" saving time by doing an "intelligent" transition from the current configuration to circle type pattern. Otherwise you would have to park all the fiber and then run the circle script. For example to configure a circle using the small fibers type at the CLI/Script Tool command line:

Fiborg3.2.0> execfile configsmallcircle

measlarge, meassmall, measfops - This scripts drive the user through the process of measuring the concentricities. The script will go fiber after fiber allowing the user to correct for fiber position and grab the button and fiber coordinates. For examples to measure the concentricities for the small fiber type:

Fiborg3.2.0> execfile meassmall

 

4. Coords Files

The coord files are the ouput files after doing the astrometry calculations for configuring a star field. The format is no different to the one of the input files to the hydraassign program but it adds an extra field for specifying the x-y plate coordinates:

FIELD NAME - <= 64 character ID.

INPUT EPOCH - Equinox of the input coordinates; must be 1855-2010.

CURRENT EPOCH - Epoch of the proposed observations, e.g., 1992.251, must be 1991-2010

SIDEREAL TIME - LST at mid-exposure, must be 0.00-23.999.

EXPOSURE LENGTH - Seconds expected for exposure, 0.0-10.0.

WAVELENGTH - Wavelength of spectrograph in A.

CABLE - Either SMALL or LARGE.

WEIGHTING - Possible answers are STRONG (default), WEAK, or NONE.

GUIDEWAVE - wavelength of TV camera, defaults to 6000 A.

After the keywords is the list of coordinates. Each coordinate entry consists of a single line, and includes the following. The format is fixed.

Integer ID (4 digits or less). This should be a unique number that allows you to tell the fiber positioner what star you are talking about if you wish to drive the gripper over that locale. It will also be kept as a secondary identifier when you reduce the data with IRAF. COLS1-4

Name (20 characters or less). This name is the principle object identifier; it will be kept with the individual spectrum when you reduce the data with IRAF. COLS 6-25

RA. This should be specified the usual way, e.g., "02 12 14.123". The leading zeros are not required. Since we are reading this numbers in a fixed format, you may include colons (or anything else) where the spaces go. COLS 27-38

DEC. This should be specified the usual way, e.g., "-01 12 13.21". For positive declinations the plus sign is optimal. The value of the degrees must be between -89 and 89, and the values of the minutes and seconds < 60. The SIGN goes into COL 40; the rest go in COLS 41-51.

CLASS. This is a one letter code that specifies what type of object this is. COL 53. Possible answers are:

C Center. There must be exactly one of these in the file; it is the coordinates of the plate center.

O Object. This is the default if the item is unspecified, and is a normal program object. Currently the maximum number of objects is 2000.

S Sky. Currently the maximum number of sky positions is 2000.

F Field orientation probe star (FOPS). Currently the maximum number of FOPS is 2000.

STATUS. This is empty, OK or a number (0-287). Empty means that the object is outside the plate bounderies. OK means that the object is inside the plate bounderies but was not assigned to a fiber. A number means that a fiber was assigned to that object.

PLATE. This are the plate coordinates of the object after astrometry corrections.

CAMERA. This are the plate coordinates seen by the camera.

 

Last Modified: April 16, 2004