Magellan/IMACS Spectroscopy of the UDS and COSMOS Fields

 

For both the UDS and COSMOS observations, the IMACS data were reduced using the COSMOS data reduction package, developed at OCIW. COSMOS produces a co-added, sky-subtracted 2-d spectrum for each slitlet. Separate reduction routines, developed as part of the DEEP2 Galaxy Redshift Survey for processing Keck/DEIMOS data, were adapted for IMACS by Renbin Yan and Michael Cooper. These routines extract 1-d spectra, measure redshifts via cross-correlation, and enable user identification of the correct redshift value for each target.

2-d Spectra



The 2-d spectra are contained in FITS files according to the naming convention "slit.mmm.sss.fits.gz" where mmm gives the mask name (e.g., UDS1) and sss gives the slit number on that mask. The data are stored in the FITS file as a binary table with the

following fields:

For each slitmask, the 2-d spectral files are packed into tarballs available for download here. Unpacking the tarballs (e.g., tar xvf sp2d.UDS1.tar) will create a subdirectory following the name of the slitmask and the 2-d spectra will be placed inside (e.g., a UDS1_sp2d subdir will be created within the current working directory with the FITS files then inside that directory).

Data Field

MASK

SLIT

NROWS

NCOLS

LAMBDA

FLUX

IVAR

Data Type

STRING

LONG

LONG

LONG

FLOAT

FLOAT

FLOAT

Brief Description

IMACS slitmask name

number of slitlet on mask

number of pixels in the spatial direction

number of pixels in the dispersion direction

a 2-d array (NCOLS x NROWS) giving wavelength as a function of pixel position

the corresponding 2-d flux array

the 2-d iverse variance array

UDS1 2-d spectra: sp2d.UDS1.tar

UDS2 2-d spectra: sp2d.UDS2.tar

UDS3 2-d spectra: sp2d.UDS3.tar

UDS4 2-d spectra: sp2d.UDS4.tar

COSMOS 2-d spectra: Coming soon

1-d Spectra



The 1-d spectra are contained in FITS files according to the naming convention "sp1d.mmm.sss.id.fits.gz" where mmm gives the mask name (e.g., UDS1), sss gives the slit number on that mask, and id gives the IMACS object id number. The data are stored in the FITS file as a binary table with the following fields:

Data Field

MASK

SLIT

ID

NCOLS

R1

R2

LAMBDA

FLUX

IVAR

Data Type

STRING

LONG

LONG

LONG

INT

INT

FLOAT

FLOAT

FLOAT

Brief Description

IMACS slitmask name

number of slitlet on mask

object id within the Magellan/IMACS sample

number of pixels in the dispersion direction

the lower limit on the range of pixel rows (R1 < pix < R2) over which the 1-d spectrum was eactracted

the corresponding upper limit on the range of pixel rows

a 1-d array (NCOLS) giving wavelength as a function of pixel position

the corresponding 1-d flux array

the 1-d iverse variance array

For each slitmask, the 1-d spectral files are packed into tarballs available for download here. Unpacking the tarballs (e.g., tar xvf sp1d.UDS1.tar) will create a subdirectory following the name of the slitmask and the 2-d spectra will be placed inside (e.g., a UDS1_sp1d subdir will be created within the current working directory with the FITS files then inside that directory).

UDS1 1-d spectra: sp1d.UDS1.tar

UDS2 1-d spectra: sp1d.UDS2.tar

UDS3 1-d spectra: sp1d.UDS3.tar

UDS4 1-d spectra: sp1d.UDS4.tar

COSMOS 1-d spectra: Coming soon