WFC3 Dataset Format

1. WFC3 Dataset Format File Formats File Name Conventions File Contents File Sizes

2. File Format Overview • File formats utilize STIS, NICMOS, and ACS heritage • Run-time and archive formats are FITS with image and table extensions • Images represented by several data arrays, collectively known as an IMSET (image set) • 2 UVIS chip images stored as 2 IMSETs in one file • IR MultiAccum readouts stored as multiple IMSETs in one file • Individual exposures – including members of CR-Splits, Repeat-Obs, and Dithers – stored in separate files • CR-Splits, Repeat-Obs, and Dithers are associated • Mosaic members (specified across >1 exposure logsheet line) are not associated WFC3 Data Formats

3. WFC3 File Names WFC3 will retain ACS and some NICMOS name conventions WFC3 Data Formats

4. Science File Contents Primary Header SCI Extension ERR Extension DQ Extension Primary Header SCI Extension ERR Extension DQ Extension x NSAMP IMSETs SAMP Extension TIME Extension • IMSET contents • UVIS (follows STIS and ACS) • Science Image (SCI) • Error Image (ERR) • Data Quality Flags (DQ) • IR (follows NICMOS) • Science Image (SCI) • Error Image (ERR) • Data Quality Flags (DQ) • Number of Samples (SAMP) • Exposure Time (TIME) x 2 IMSETs WFC3 Data Formats

5. Science File Contents (cont.) • RAW • UVIS: 2 raw IMSETs from one exposure (1 IMSET per chip) • IR: NSAMP raw IMSETs from one exposure • IMA • IR only: NSAMP calibrated IMSETs from one exposure • FLT • UVIS only: 2 calibrated IMSETs from one (non-CRSPLIT) exposure • CRJ • UVIS: 2 calibrated and CR-cleaned IMSETs from multiple CR-SPLIT exposures • IR: 1 calibrated and CR-cleaned IMSET from one exposure (CR rejection accomplished via MultiAccum readout combination) WFC3 Data Formats

6. Science File Contents (cont.) • SFL • UVIS: 2 calibrated and summed IMSETs from Repeat-Obs exposures • IR: 1 calibrated and summed IMSET from Repeat-Obs exposures • DTH • UVIS and IR: 1 calibrated and drizzled IMSET from Dithered exposures WFC3 Data Formats

7. Association Tables Follows ACS Conventions *CR-Splits and Repeat-Obs are mutually exclusive within a single association WFC3 Data Formats

8. Sample Association Tables CR-SPLIT=3, No Dither CR-SPLIT=2, 2-position Dither WFC3 Data Formats

9. Sample Association Tables 4-position Dither, CRSPLIT=REPEATOBS=0 WFC3 Data Formats

10. Trailer File • Follows ACS Design • CALWF3 modules write to explicitly-chosen trailer files • Pre-CALWF3 modules (e.g. Generic Conversion, WCS) create and populate individual trailer file for each exposure • CALWF3 modules that process individual exposures append to existing individual trailer files • CALWF3 modules that process multiple exposures append to concatenated product trailer file (contains log for all members and products) WFC3 Data Formats

11. Keywords • UVIS and IR images will use separate sets of keywords • Reuse ACS WFC for WFC3 UVIS and NICMOS for WFC3 IR keywords, as appropriate • Minor differences between ACS WFC and NICMOS keyword conventions (e.g. “dqicorr” vs. “maskcorr”) resolved by adopting ACS WFC conventions for both UVIS and IR images • Keeps WFC3 UVIS consistent with STIS and ACS • Keeps WFC3 UVIS consistent with WFC3 IR • Results in minor differences between NICMOS and WFC3 IR WFC3 Data Formats

12. WFC3 File Sizes UVIS IR 1 2 MB per readout 2 10.5 MB per readout WFC3 Data Formats