2.4 From the Phase II Proposal to Your Data

The connection between the Exposure Logsheet that each observer fills out during the Phase II proposal process and the datasets and associations that the observer receives once the observations are executed can be better understood through some examples.

The first example shows an exposure logsheet entry that will generate only one dataset:

Exposure_Number: 1 Target_Name: HDF Config: NIC2 Opmode: MULTIACCUM Aperture: NIC2 Sp_Element: F160W Optional_Parameters: SAMP-SEQ=STEP256,NSAMP=12 NUMBER_of_Iterations: 1 Time_Per_Exposure: DEF Special_Requirements: POS TARG 0.5, 0.5

The science data file in the dataset will contain 13 imsets (corresponding to the MULTIACCUM NSAMP=12 parameter plus the 0’th read), and some of the header keywords will be filled with the relevant information from the target and exposure logsheets of the Phase II (e.g., the keywords targname, ra_targ, dec_targ,....).

The next example shows an exposure logsheet entry that will generate both multiple datasets and an association:

Exposure_Number: 1 Target_Name: HDF Config: NIC2 Opmode: MULTIACCUM Aperture: NIC2 Sp_Element: F160W Optional_Parameters:PATTERN=SPIRAL-DITH-CHOP,NUM-POS=8, DITH-SIZE=1.5,CHOP-SIZE=25.0,SAMP-SEQ=STEP256,NSAMP=12 Number_of_Iterations: 1 Time_Per_Exposure: DEF Special_Requirements:

In this observation, eight datasets (one for each position of the pattern) and one association will be created. The pipeline products will include the eight reduced datasets, one mosaic of the background-subtracted target, and one mosaic of the background.

An association will be generated also in the case below:

Exposure_Number: 1 Target_Name: HDF Config: NIC2 Opmode: MULTIACCUM Aperture: NIC2 Sp_Element: F160W Optional_Parameters: SAMP-SEQ=STEP256,NSAMP=12 NUMBER_of_Iterations: 3 Time_Per_Exposure: DEF Special_Requirements:

The number of iterations is 3, implying that three datasets will be generated from this exposure logsheet, plus an association table containing the three datasets. The collection of multiple iterations into an association is a new feature introduced by the NICMOS and STIS pipelines. In our specific example, the co-added image from the three iterations will be one of the products of the pipeline.