1.3-m SMARTS Photometric Calibrations in JHK
Beginning in August 2008, calculation of the photometric zeropoint has been done each photometric night for two IR standards stars, one red and one blue, using the task PHOT in the IRAF package DIGIPHOT/APPHOT. The settings for the program tasks centerpars, datapars, findpars, fitskypars and photpars are given at the bottom of this page.
1. The value of theZeropoint Correction, Z, as given by the equation
Z = Instrumental Mag - Literature Mag - (Extinction Coeff)*(Airmass)
where Instrumental Mag is the PHOT result obtained with an aperture radius of 25 pixels and Literature Mag is the magnitude reported by suitable sources.
2. Other Photometric Values
To date, it has not been possible to calculate values for Color Term Coefficients or Color-Term Corrected Zeropoint Corrections or Extinction Coefficients. For use in the above equation for calculating the zeropoint, Extinction Coefficient values are the literature values reported by Frogel (http://adsabs.harvard.edu/abs/1998PASP..110..200F), namely 0.100, 0.055 and 0.085, in J, H, and K, respectively.
SETTINGS FOR THE PHOT PROGRAMS TASKS============================
| PACKAGE = apphot | |||
| TASK = centerpars | |||
| (calgori= | centroid) | Centering algorithm | |
| (cbox = | 10.) | Centering box width in scale units | |
| (cthresh= | 0.) | Centering threshold in sigma above background | |
| (minsnra= | 1.) | Minimum signal-to-noise ratio for centering algo | |
| (cmaxite= | 10) | Maximum number of iterations for centering algor | |
| (maxshif= | 5.) | Maximum center shift in scale units | |
| (clean = | no) | Symmetry clean before centering ? | |
| (rclean = | 1.) | Cleaning radius in scale units | |
| (rclip = | 2.) | Clipping radius in scale units | |
| (kclean = | 3.) | Rejection limit in sigma | |
| (mkcente= | yes) | Mark the computed center on display ? | |
| (mode = | ql) | ||
|
PACKAGE = apphot TASK = datapars |
|||
| (scale = | 1.) | Image scale in units per pixel | |
| (fwhmpsf = | 8.) | FWHM of the PSF in scale units | |
| (emission = | yes) | Features are positive ? | |
| (sigma = | INDEF) | Standard deviation of background in counts | |
| (datamin = | -500.) | Minimum good data value | |
| (datamax = | 15000.) | Maximum good data value | |
| (noise = | "poisson") | Noise model | |
| (ccdread = | "") | CCD readout noise image header keyword | |
| (gain = | "") | CCD gain image header keyword | |
| (readnoise = | 20.) | CCD readout noise in electrons | |
| (epadu = | 7.2 ) | Gain in electrons per count | |
| (exposure = | "EXPTIME") | Exposure time image header keyword | |
| (airmass = | "SECZ") | Airmass image header keyword | |
| (filter = | "IRFLTID") | Filter image header keyword | |
| (obstime = | "JD") | Time of observation image header keyword | |
| (itime = | ) | Exposure time | |
| (xairmas= | ) | Airmass | |
| (ifilter= | J) | Filter | |
| (otime = | JD) | Time of observation | |
| (flpar = | no) | flush pfile on assign? | |
| (mode = | "ql") | ||
|
PACKAGE = apphot TASK = findpars |
|||
| (thresho= | 4.) | Threshold in sigma for feature detection | |
| (nsigma = | 1.5) | Width of convolution kernel in sigma | |
| (ratio = | 1.) | Ratio of minor to major axis of Gaussian kernel | |
| (theta = | 0.) | Position angle of major axis of Gaussian kernel | |
| (sharplo= | 0.2) | Lower bound on sharpness for feature detection | |
| (roundlo= | 1.) | Upper bound on sharpness for feature detection | |
| (roundhi= | -1.) | Lower bound on roundness for feature detection | |
| (mkdetec= | 1.) | Upper bound on roundness for feature detection | |
| (mode= | ql) | Mark detected stars on the display ? | |
|
PACKAGE = apphot TASK = fitskypars |
|||
| (salgori= | mode) | Sky fitting algorithm | |
| (annulus= | 30.) | Inner radius of sky annulus in scale units | |
| (dannulu= | 10.) | Width of sky annulus in scale units | |
| (skyvalu= | 0.) | User sky value | |
| (smaxite= | 10) | Maximum number of sky fitting iterations | |
| (sloclip= | 0.) | Lower clipping factor in percent | |
| (shiclip= | 0.) | Upper clipping factor in percent | |
| (snrejec= | 50) | Maximum number of sky fitting rejection iteratio | |
| (sloreje= | 3.) | Lower K-sigma rejection limit in sky sigma | |
| (shireje= | 3.) | Upper K-sigma rejection limit in sky sigma | |
| (khist = | 3.) | Half width of histogram in sky sigma | |
| (binsize= | 0.1) | Binsize of histogram in sky sigma | |
| (smooth = | no) | Boxcar smooth the histogram | |
| (rgrow = | 0.) | Region growing radius in scale units | |
| (mksky = | no) | Mark sky annuli on the display | |
| (flpar = | no) | flush pfile on assign? | |
| (mode = | ql) | ||
|
PACKAGE = apphot TASK = photpars |
|||
| (weighti= | constant) | Photometric weighting scheme for wphot | |
| (apertur= | 2,5,15,25) | List of aperture radii in scale units | |
| (zmag = | 25.) | Zero point of magnitude scale | |
| (mkapert= | no) | Draw apertures on the display | |
| (flpar = | no) | flush pfile on assign? | |
| (mode = | ql) | ||
Printer-friendly version