Calibration Reference Data System
COS Reference Files

Reference files used by the COS calibration pipeline (CALCOS)) are updated on a regular basis. Current reference files files can be retrieved from the HST archive, or downloaded directly from the lref directory. Note that FTP access is browser dependent: Safari does not work; Firefox or Chrome may or may not work depending on the Operating System. If you cannot download the files via Firefox or Chrome, you can try using a standalone FTP tool or accessing the ftp site directly (ftp ftp.stsci.edu) with 'anonymous' (without quotes) as your username and your email address as your password.

If you would like to receive an e-mail every time a new COS reference file is delivered and the database is updated, you can subscribe to the cos_reffiles_upd mailing list. To subscribe to this list, send an e-mail to MajorDomo @ stsci.edu with the following in the body of the message:
subscribe cos_reffiles_upd your_address .

New tools for exploring COS Reference Files are now available at https:/hst-crds.stsci.edu. To get a listing of the reference files you're interested in, click on 'cos' then select the filetype. Use the names below in the Header Keyword column as a guide.

Reference File Type	Extension	Header Keyword	Detector
Flat Field Files Accounts for pixel-to-pixel variations. More...	flat	FLATFILE	Both
Geometric Distortion Correction Images Corrects for the intrinsic nonlinearity (INL) of the FUV detector. More...	geo	GEOFILE	FUV
Bad Time Interval Table Lists the start and end times of known bad time intervals. More...	badt	BADTTAB	FUV
Baseline Reference Frame Table Used when applying the thermal distortion correction. More...	brf	BRFTAB	FUV
Burst Parameters Table Provides the parameters needed for deciding when the count rate in some time interval in FUV time-tag data is too high to be regarded as normal. More...	burst	BRSTTAB	FUV
1-D Extraction Parameters Table Gives the location of the spectrum to be extracted from a 2-D image. More...	1dx	XTRACTAB	Both
Bad Pixel Table Gives the locations of rectangular regions that cover portions of the detector that are known to be less than optimal. More...	bpix	BPIXTAB	Both
Deadtime Reference Table Used to obtain the true number of events received compared to the number of events counted by the detector electronics. More...	dead	DEADTAB	Both
Dispersion Coefficients Table Gives a set of polynomial coefficients for computing wavelength from pixel number. More...	disp	DISPTAB	Both
Calibration Lamp Spectra Table Used to determine the pixel offset of the observed data. More...	lamp	LAMPTAB	Both
Pulse Height Parameters Table Lists the lower and upper thresholds for valid individual pulse heights in TIME-TAG mode as well as the minimum and maximum values for the location of the mean value of the pulse height distribution used in ACCUM mode. More...	pha	PHATAB	FUV
Photometric Sensitivity Reference Table Provides the information needed to convert from corrected detector counts to flux units. More...	phot	FLUXTAB	Both
Spectroscopic WCS Parameters Table The spectroscopic WCS parameters table gives values to be used for populating the world coordinate keywords. More...	SPWCS	SPWCSTAB	Both
Time Dependent Sensitivity Table Gives information about the relative sensitivity as a function of time and wavelength. More...	tds	TDSTAB	Both
Wavecal Parameters Table Gives information about the relative sensitivity as a function of time and wavelength. More...	wcp	WCPTAB	Both
High Voltage Reference Table The high voltage reference table gives the times when the FUV high voltage was changed More...	hv	HVTAB	FUV
Walk Correction Reference Table The walk corection reference table gives parameters for correcting the pixel coordinates XCORR and YCORR of FUV TIME-TAG data More...	walk	WALKTAB	FUV
Gain Sag Reference Table The gain sag reference table gives the locations of rectangular regions for portions of the FUV detector that have very low pulse height amplitude (PHA). More...	gsag	GSAGTAB	FUV