CDBS Operations

Calibration Data Base and Operations


CDBS (Calibration Data Base System) is a pathway of software, protocol, and procedures which starts with several groups of Instrument Scientist teams collecting all of the various forms of calibration data, packaging it and delivering to CDBS. The data is put through CDBS Operations with the end result being delivery to HST's ground system reduction pipeline (OPUS), archiving to the Data Archiving and Distribution System (DADS), and population of the CDBS on-line archives.

Follow the links for more information about CDBS Operations, OPUS, DADS, and all calibration data.


For a postscript copy of the delivery procedures (which have been described above), click on

Delivery Procedures for all instrument data.




Appendix information, click on Appendix.


Query the CDBS database....CDBS Query


Note: We no longer keep and WFPC (I),HSP, or STIS data and/or information on-line. Data is available in DADS using StarView.

Note: When accessing files, be aware of the different formats these files and tables are in . If you don't pay attention to these formats, you may end up with

(roadkill, for your trouble)!!!!!!!!


CDBS OPERATIONS




CDBS (Calibration Database System) Operations maintains the HST Calibration Database. We receive and process calibration data delivered
to us from instrument teams. The data will eventually be used in reduction routines both in OPUS and offline programs.

To get an idea of what happens when data comes into CDBS and is processed, we've captured the screen results from a WFPC2 delivery. Four sets of files came in along with an associated load file for each set. The particular reference file type in this example is DRK. Take a look at:
Deliver CDBS.

Many of the tasks, such as certify, expload, loopfits, mkcomptab, mkload, and uniqname, all part of deliver_cdbs, were written by Bernie Simon and has been documented at the following link: CDBS Tools

Rick Whitman, Steve Lubow, and Shaw-Hong Kao are the other authors of these tools. Postscript files are available for each process or for general information about CDBS and/or the Calibration Database:

CDBS Documentation

It is recommended that you use gv instead of ghostview in your netscape browser, but either will work when viewing postscript files.


Data Delivery Procedures


Once OPUS has installed the data, the ground system has the latest reference calibration data to be used for any observations coming through the system. A feedback mechanism brings information back to CDBS from OPUS on the verification of installation and on the exact installation time. Additional steps of operations involves entering paper forms which track the whole process into the CDBS library, and notifying Instrument Scientist of the installation into OPUS.


For a postscript copy of the delivery procedures (which have been described above), click on

Delivery Procedures

for all instrument data.

To get a postscript copy of the delivery form, click on Data Delivery Form.


Reference File and Table Structure


All of the data we have online is a combination of reference files (Geis header and data pairs and FITS files) and STSDAS tables. Except for the header files, all are binary and need special utilities to read them. For more information on this, go to File Structures.

You may want to use our new Query system to directly query the Calibration Data Base [CDBS Query], or if you know what you are looking for (known filenames, for example), this may be an easy route for retrieving data. If you do not know what you are looking for and do not want to use the CDBS Query, it may be better to get the data through StarView, which will retrieve from DADS and not our on-line archives.


Ground System - OPUS


OPUS only keeps current data while CDBS retains all versions, historical data going back, in some cases, to pre-launch laboratory data. In many cases the calibration data used by OPUS at the time of the observation are updated later. Therefore, CDBS may have better data than was used to calibrate the observation. Observers are advised to check for this situation and possibly recalibrate their observations using
STSDAS/IRAF with more up-to-date calibration files. By use of the tool StarView, this information can be determined. It is also wise to check with the individual instrument teams.

OPUS has a web page with much much more information.


Component Throughput Data


HST Throughput Tables are also kept in CDBS. These tables give coefficients of transmission as a function of wavelength and including an associated error value. The individual tables for each instrument are accessed through a system using a master component table and a master graph table. This data is used in conjunction with the STSDAS software package Synphot for off-line calibration as well as being used in Opus for standard pipeline calibrations.

For history tracking reasons, we rename all of the master component and graph tables and keep them in a separate directory called MTAB . The MTAB directory contains HST master component and graph tables which have been delivered to OPUS, renamed using the uniqname schema. The extensions denote the type of file each represents:


Other Types of Data



There are different data types which do not get delivered to OPUS.

These are:

More information about the naming of reference data, extensions, associated file types, and database relation names is in File Structures.


Back to the Calibration Data and Tools page

Maintained by Calvin Tullos
STScI Observatory Science Group
Last modified, Sept 16 1997