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PhoSim Instance Catalog Definition

This is the main input file to PhoSim. There are two parts to the instance catalog: the observation parameters and the astrophysical inputs. Neither has any required inputs! PhoSim is fully capable of choosing realistic and self-consistent values, so only use the commands below to specify what is important to your particular simulation.

Observation Parameters

The observation parameters have no required inputs. The values will either be calculated self-consistently from other parameters or chosen from a distribution.

Standard inputs

The standard inputs are listed below which specify pointing, observation time, camera rotation, filter configuration, and exposure information. A common method is to choose to either specify ra/dec or alt/az, but not both. However you can choose both as well for certain applications and PhoSim will still function with inconsistent parameters with the MJD/latitude/longitude. Unspecified parameters that cannot be calculated self-consistently are chosen from a distribution.

rightascension X X = Unrefracted Right Ascension in decimal degrees

declination X X = Unrefracted Declination in decimal degrees

azimuth X X = Unrefracted Azimuth in decimal degrees

altitude X X = Unrefracted Altitude in decimal degrees

mjd X X = Modified Julian date (MJD) of observation (e.g. 51544.5)

camtelangle X X = Angle of telescope relative to camera in decimal degrees (also rottelpos)

filter X X = Filter number (starting at 0)

obstime X X = Total observation time in seconds of the sequence*

numexp X X = Number of exposures in the sequence

*Note for CCDs the obstime includes the read times (r) between the exposures (e), but not the last read: X = N e + (N-1) r. For CMOS devices, the number of reads is simply X divided by the frame rate for that specific device.

Advanced inputs to override self-consistent calculations and distributions

The following sun/moon parameters or environmental parameters listed below would most likely not be used because they can be self-consistently calculated by PhoSim. However, they can be specified and do not have to be consistent for certain studies. For example, you could move the Moon below the horizon even if its not there for a given date/time. Or you could pretend you are an observer waiting for a particular good seeing value or cloud cover by specifying the seeing or cloud cover.

date X X = Date of observation in format: 2000/1/1/0.5

camskyangle X X = Angle of sky relative to camera coordinates (from North over East) in decimal degrees (also rotskypos)

moondec X X = Declination of Moon in decimal degrees

moonra X X = Right Ascension of Moon in decimal degrees

moonalt X X = Altitude of Moon in decimal degrees

moonaz X X = Azimuth of Moon in decimal degrees

moonphase X X = Phase of Moon from 0 to 100

sunalt X X = Altitude of Sun in decimal degrees

sunaz X X = Azimuth of Sun in decimal degrees

seeing X X = Seeing at zenith at 500 nm (-1 for random)

temperature X X = Temperature in Celsius

pressure X X = Pressure in mmHg

Advanced inputs for detailed instrument configuration

The following bookkeeping and configuration parameters listed below are also optional, but useful for simulation of calibration data (see the walkthrough), naming files, or setting the random number seed.

obsid X X = observation identifier (names files)

seed X X = random number seed

minsource X X = minimum number of source on chip to bother to simulate it (default X=1)

telconfig X X = telescope config (0=dome open/dome light off ; 1=dome closed/dome light off; 2=dome closed/dome light on)

control X X = 0/1 for whether the control system is on (default X=1)

rotationtracking X X = 0/1 for whether there is rotation tracking during the exposure (default X=1)

move X Y X = degree of freedom (instrument-specific)

Y = amount of motion (usually mm or degrees)

isdithered X X = 0/1 (not used in phosim, except in header)

ditherra X X = distance (degrees) (not used in phosim, except in header)

ditherdec X X = distance (degrees) (not used in phosim, except in header)

camconfig X X = camera config (bitmask where first bit is science sensors on; second is wavefront sensors on; third is guiders on)

overdepbias X X = operating voltage of CCD

ccdtemp X X = CCD temperature relative to nominal (K)

focus X Y Z X = number of focus steps, Y = focus step size in microns, Z = separation in arc seconds of lateral shifts

nframes X X = number of recorded frames for CMOS-type sensors in each group of reads (default X=1)

nskip X X = number of frames skipped between reads for CMOS-type sensors in each group of reads (default X=0)

driftx X X = drift scan rate of the detector in the x-direction (pixels/second)

drifty X X = drift scan rate of the detector in the y-direction (pixels/second)

domeint X X = dome light intensity (mag per sq. arcseconds), if on

domewav X X = wavelength of dome light (nm), 0 to use flat SED

Astrophysical inputs

The astrophysical inputs have no required inputs, but you will have to do at least one object or catalog command to produce any photons.

Automatic Catalog Generation

There are a series of catalog generating commands that will automatically make a set of stars and galaxies.

stars X Y Z X=lower magnitude limit, Y=upper magnitude limit, Z=diameter of catalog in degrees

galaxies X Y Z X=lower magnitude limit, Y=upper magnitude limit, Z=diameter of catalog in degrees

stargrid X Y Z X=spacing of sources in degrees, Y=size of catalog in degrees, Z= magnitude of sources

includeobj X X=external file that has a list of objects. This is used only for massive catalogs.

Individual Object Specification

For every object you wish to add, put the following line at the end of the instance catalog file. Note: an astrophysical object could be composed of more than one line (e.g. a bulge and disk of a galaxy). This enables complex wavelength-dependent morphologies.

object ID RA DEC MAG_NORM SED_NAME REDSHIFT GAMMA1 GAMMA2 KAPPA DELTA_RA DELTA_DEC SOURCE_TYPE source_pars DUST_REST_NAME dust_pars_1 DUST_LAB_NAME dust_pars_1

ID A floating point number to keep track of the object, which is unused by PhoSim

RA The right ascension of the center of the object or image in decimal degrees

DEC The declination of the center of the object in decimal degrees

MAG_NORM Flux in AB magnitudes at 500 nm in the source's rest frame. (Approximately V or g)

SED_NAME The name of the SED file relative to the SED directory

REDSHIFT The redshift (or blueshift) of the object. The SED does not need to be redshifted if using this.

GAMMA1 Shear parameter gamma1 used in weak lensing.

GAMMA2 Shear parameter gamma2 used in weak lensing.

KAPPA Magnification parameter in weak lensing.

DELTA_RA RA offset in radians for weak lensing or objects that moved from

another exposure without modifying the first two columns.

DELTA_DEC Declination offset in radians for weak lensing or objects that moved from

another exposure without modifying the first two columns.

SOURCE_TYPE The name of the spatial model to be used as defined below.

spatial_pars The associated parameters for each spatial model.There could be none or many.

While the parser is reading the model it looks for more parameters based on the name of the model.

DUST_REST_NAME Dust model name in the object's rest frame. This is either the ccm for the CCM model,

or calzetti for the calzetti model. If no dust model is desired, then put none for this field.

dust_pars_1 The parameters for both the calzetti and CCM are the A_v followed by the R_v value.

If no dust model is used, do not use parameters.

DUST_LAB_NAME Dust model name in the lab frame. This is either the ccm for the CCM model, or calzetti for the calzetti model.

If no dust model is desired, then put none for this field.

dust_pars_2 The parameters for both the calzetti and CCM are the A_v followed by the R_v value.

If no dust model is used, do not use parameters

Spatial Models

point This is a model primarily used for stars, but also unresolved objects.

This has no parameters.

gauss This is a model for a gaussian-shaped object.

1 parameter: sigma in arcseconds

movingpoint This is a point source that will move appreciably during the exposure (e.g. asteroid)

2 parameters: the derivative of the velocity arcseconds per second and the position angle in degrees

sersic2D This is a 2-dimensional (projected on the sky) elliptical Sersic model for a simple galaxy shape.

4 parameters: half-light radius of semi-major axis in arcseconds,

half-light radius of semi-minor axis in arcseconds,

position angle in degrees, and sersic index

sersic This is a 3-d dimensional ellipsoidal Sersic model.

7 parameters: size of axis 1 in arcseconds, size of axis 2 in arcseconds, size of axis 3 in arcseconds,

angle 1 in degrees, angle 2 in degrees, angle 3 in degrees, and sersic index

sersicDisk This is a 2-d Sersic model with an exponential-scale height in the third dimension

6 parameters: half-light radius of semi-major axis in arcseconds, half-light radius of semi-minor axis in

arcseconds, the exponential scale height, polar angle in degrees, position angle in degrees, sersic index

sersicComplex This a full 3-d galaxy model with both irregular knots and spiral structure. By choosing parameters,

you can continuously represent elliptical, spiral, and irregular galaxies.

14 parameters: size of axis 1 in arcseconds, size of axis 2 in arcseconds, size of axis 3 in arcseconds,

angle 1 in degrees, angle 2 in degrees, angle 3 in degrees, sersic index, fraction of light in clumps,

number of clumps, gaussian clump size in arcseconds, fraction of light in spiral, winding angle of spiral in

degrees, spiral bar size in arcseconds, spiral gaussian width in arcseconds, position angle of spiral

sersicDiskComplex This is a full galaxy model disk model with irregular knots and spiral structure,

but with an exponential disk scale height.

14 parameters: size of axis 1 in arcseconds, size of axis 2 in arcseconds,

size of disk scale height in arcseconds, angle 1 in degrees, angle 2 in degrees, angle 3 in degrees,

sersic index, fraction of light in clumps, number of clumps, gaussian clump size in arcseconds,

fraction of light in spiral, winding angle of spiral in degrees, spiral bar size in arcseconds,

spiral gaussian width in arcseconds, position angle of spiral

sphere This is a 3-d sphere.

1 parameter: radius in arcseconds

disk This is a 2-d disk.

1 parameter: radius in arcseconds

reflectedsphere This is a 3-d sphere illuminated by another object (e.g. planet).

3 parameters: radius in arcseconds, angle of illumination in degrees (0=direct, 180=behind),

and rotation angle in degrees of the illuminating source

distortedSphere This is a 3-d sphere distorted by spherical harmonics with an emission profile that follows a power law.

10 parameters: power law index, 9 spherical harmonic coefficients in arcseconds

movingsphere This is a 3-d sphere that is moving.

3 parameters: angular velocity in arcseconds per second, position angle of motion in degrees,

and radius in arcseconds

movingdisk This is a 2-d disk that is moving.

3 parameters: angular velocity in arcseconds per second, position angle of motion in degrees,

and radius in arcseconds

movingreflectedsphere This is a 3-d sphere illuminated by another object (e.g. planet) that is moving.

5 parameters: angular velocity in arcseconds per second, position angle of motion in degrees,

radius in arcseconds, angle of illumination in degrees (0=direct, 180=behind), and

rotation angle in degrees of the illuminating source

FITS files If the SOURCE_TYPE contains the word fits or fit, it will look for that file in the image directory

2 parameters: pixel size (in arcseconds) and rotation angle (in degrees).

RA goes to the left and DEC goes up in physical coordinate

Note that PhoSim will not use the header information, because you may want to use the same image

in multiple field locations.

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