GEMS Datalist Column Headings and Notes

GEMS Tile Number

GEMS tile number (see chart). Underneath the tile number in the v band is a link to a finder chart from the DSS. Underneath the tile number in the z band is a link to a preview image.

Filter

Data taken in two filters (V=F606W and z=F850LP).

Dataset

Original HST Dataset Name. The dataset name is a link is to a information or preview page for that observation.

Coordinates

Right Ascension and Declination

Roll Angle

Roll angle of the original observation.

Dither Step) Raw Image

Calibrated Files used as input to the GEMS team processing pipeline.

sec

Exposure times of the input frames [sec].

HLSP File Names

Filenames of the final High-Level Science Products (HLSP). The filename is a link to download the data. To retrieve the entire set of HLSP,

ftp archive.stsci.edu
logon as anonymous
cd /pub/hlsp/gems

You will see two directories: v_mk1 which contains the science and weight files for the mark1 v filter data and z_mk1 which contains the science and weight files for the mark1 z filter data.
Remember to set to binary.

Filename Nomenclature:
h_gems_v01_mk1.fits mark1 (version 1) reduction of the V image of tile 01
h_gems_s01_mk1.fits microregistered ("shifted") version of preceding
h_gems_z01_mk1.fits mark1 reduction of the z image of tile 01
 
h_gems_v01_mk1_wt.fits weight image of preceding
h_gems_z01_mk1_wt.fits ditto
Note: the shifted mk1 weight images and the shifted mk2 science and weight images can be produced from the corresponding V images using the following measured shifts; the images have not been produced for this archive
 
h_gems_v01_ep1.fits GOODS epoch 1 data reduced in mark1
h_gems_z01_ep1.fits ditto
h_gems_v01_ep1_wt.fits weight image of preceding
h_gems_z01_ep1_wt.fits ditto

V2 rms V3

The rms scatter (mas) in the V2 and V3 coordinate axes during the observations, a measure of the quality of the guiding versus perturbing effects such as micro-impacts.

expo

Sum of the exposure times of the input frames [sec].

sky

Sum of the average sky levels of the input frames [ct].

sig/pxl

sqrt( sky + 25 x nexpo ) [ct]

the basic photometric sigma per pixel in ct, including sky and readnoise but excluding the inverse flatfield; nexpo is the number of input frames

Cutouts of Notable Objects

Cutouts of objects of interest within the tile. These are a personal selection made and provided by GEMS team member, John Caldwell. The names of the cutouts are based on the xy location in the mk1 image.