The data are organized into sets of images by passband (NICMOS F110W & F160W) and by the tiled GOODS “sections”. Each GOODS NICMOS section is 2,730 x 2,730 pixels in size and a scale of 0.09 arcsec/pixel. There are 17 sections in the GOODS NICMOS North field and 18 sections the GOODS NICMOS South field. For each section we provide the drizzled science image, a weight image and a DS9 region file. The label for each sections is identical to the GOODS Version 2.0 data release.
The files name contains information relative to the sections in the GOODS fields (north or south), the passband (F110W or F160W), the data release version (v1.0 in this case), the section, and the image type (science image or a weight map). For example, the FITS file containing the F160W science data for section 11 in the GOODS South field is called
hlsp_goodsnic_hst_nicmos_south-sect11_F160W_v1_drz_sci.fits
The pixel values of the science images report the flux count rate calibrated in electron/second. The zero points to convert the count rate into an AB magnitude for the two GOODS NICMOS passbands are the following:
| Filter | Zeropoint |
|---|---|
| F110W | 25.27 |
| F160W | 25.17 |
The final mosaic science images where generated by the NICMOS data reduction pipeline NICRED which uses the MultiDrizzle package. For a detailed discussion of the drizzling process see the MultiDrizzle Handbook.
The weight map image is generated by MultiDrizzle and is equal to the inverse variance (i.e., 1/rms^2) per pixel. A detailed discussion of weight map conventions and noise correlation in drizzling, can be found in Casertano et al. 2000, AJ, 120, 2747, especially Section 3.5 and Appendix A.
The DS9 region file contains polygons that will display the outline footprint of each region within a section that contain data. The polygon region vertices are listed in sky coordinates, therefore, can be used display the section footprint on any image loaded into DS9 with a valid WCS.