2.2 COS File Names

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The naming convention for COS files is rootname_*.fits, where rootname follows the ipppssoot naming convention (see Chapter 2 of the Introduction to HST Data Handbooks), and * is a three to nine character file suffix. The suffix identifies the type of data within the file. All FUV data files with the exception of the lampflash, x1d, and x1dsum files will have an additional suffix of _a or _b (e.g., rootname_*_[a,b].fits) to denote the detector segment. However, if segment=A is specified in the Phase II proposal there will be no corresponding _b files and vice versa. The FUV lampflash, x1d, and x1dsum files will always be segment combined and therefore will not have the additional suffix.

Table 2.1 lists the file suffixes for the COS data files and indicates which files are produced by the different types of observations. Depending on the type of observation, and the path it has taken through the calibration pipeline (see calibration flow charts; Figure 3.1–Figure 3.6), there will be an appropriate subset of these files in a given dataset. Note, the format of some of the COS files can be different depending on the observing mode; see Section 2.3 for more details.

COS data utilize a modified naming convention from other HST instruments. In, particular COS FUV files can have TWO suffixes. The first suffix identifies the filetype and the second suffix if present identifies the FUV detector segment. For the remainder of this document the use of "suffix" will refer to the first suffix which identifies the filetype and will always include filetypes with the additional FUV segment suffix if they exist.

Table 2.1: Data Types and File Naming Conventions for Different COS Observation Types

Long
Suffix

Data
Format

Spectroscopic

Imaging

Contents

FUV

NUV

NUV

TIME-TAG

ACCUM

TIME-TAG

ACCUM

TIME-TAG

ACCUM


 

Uncalibrated Science Data

rawtag

table


 
 

x


 

x


 

Raw NUV TIME-TAG events list

rawtag_a,
rawtag_b

table

x


 
 
 
 
 

Raw FUV TIME-TAG events list

rawaccum

image


 
 
 

x


 

x

Raw NUV ACCUM image

rawaccum_a,
rawaccum_b

image


 

x


 
 
 
 

Raw FUV ACCUM image

rawacq

table or image


 
 
 
 
 

x

Raw acquisition file

pha_a,
pha_b

image


 

x


 
 
 
 

Pulse height distribution


 

Uncalibrated Support Data

asn

table

x

x

x

x

x

x

Association file

jit

table

x

x

x

x

x

x

Spacecraft pointing data averaged over 3 s intervals

jif

image

x

x

x

x

x

x

2-D histogram of the _jit file

spt

image

x

x

x

x

x

x

Support, planning and telemetry information

trl

table

x

x

x

x

x

x

Trailer file with a historical record of generic conversion processing


 

Intermediate Data Products

trl

table

x

x

x

x

x

x

The raw trailer file is updated with a historical record and errors log of calibration pipeline processing1

tra, logtxtxxxxxxSame as _trl file but in text format

corrtag2

table


 
 

x


 
 
 

NUV TIME-TAG events list with calibrated values

corrtag_a,2
corrtag_b2

table

x


 
 
 
 
 

FUV TIME-TAG events list with calibrated values

flt

image


 
 

x

x

x

x

NUV flat-fielded science image

flt_a,
flt_b

image

x

x


 
 
 
 

FUV flat-fielded science image

counts

image


 
 

x

x

x

x

NUV not flat-fielded science image

counts_a,
counts_b

image

•

•


 
 
 
 

FUV not flat-fielded science image

lampflash

table

x3


 

x3


 
 
 

1-D extracted TAGFLASH (FLASH=yes) spectra

x1d

table

x

x

x

x


 
 

1-D extracted spectra for a single exposure

x1dsum<n>4

table

x

x

x

x


 
 

Averaged 1-D extracted spectra for multiple exposures with the same grating, central wavelength, aperture and FP-POS=<n>


 

Final Data Products

fltsum

image


 
 
 
 

x

x

Summed flat-fielded image (imaging only). Final calibrated association product for all COS imaging datasets.

x1dsum

table

x

x

x

x


 
 

Final combined 1-D extracted spectra for multiple exposures with the same grating, central wavelength and aperture combining all FP-POS. Final calibrated association product for all COS spectroscopic datasets.

1 Only updated during processing and ingestion by the HDA. When reprocessing data in a user's home environment the trl file will not be updated. Instead reprocessing will generate an ASCII tra file.
2 For ACCUM data the time stamps in the first extension are set to the median value in the corrtag files; each count in the rawaccum file becomes an event. See Section 2.4.2.
3 Only for TIME-TAG with FLASH=yes (TAGFLASH mode).
4 <n> can be 1,2,3,4 and denotes the FP-POS number.

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