Time Dependent Calibration Files

Before proceeding with making or re-naming any time dependent calibration files first (re-)familiarize yourself with Calibration File Naming.

SSC Conventions - Time Dependent File Names

Some SSC files are time dependent.
They are only valid for calibrating files from observations taken at specific times.
Usually a time dependent file is valid for one or more entire observing campaigns.
Time dependent files have names of the form :

module_name_starttime_finishtime.type

The start and finish times are in "system clock" times.
For each indivdual observation BCD file its observation time is denoted by the "SCLK_OBS" FITS keyword in the file header.

File name example : b3_r240_dark_850003427_851556224.fits

IRS Module Bias Changes

To improve overall performance (at the expense of some sensitivity) bias voltages of some of the IRS modules have been changed at various times during the SIRTF/Spitzer mission.
The upshot of this is that different calibration files then have to be used to process data depending on the bias voltage in use at the time any gven observation was made.
The Calibration Files to be used are designated by the value of the "CAL_SET" FITS header keyword in the relevant BCD file(s).
(The "CAL_SET" keyword is added to each relevant FITS file header by the SSC pipeline when preparing "bcd" files for release.)
Currently the relevant bias changes are :

"CAMPAIGN" FITS keyword value(s)
(SSC Format)
Campaigns
(IRS Team Format)
"CAL_SET" FITS keyword value(s)
| | | |'IRSX002500' - 'IRSX005500'

'IRSX005700' - 'IRSX009800'

'IRSX009900' onwards. |1 - 24

25 - 44

45 onwards. |'CXX.0PRE25.A' - where "XX" designates the pipeline version used.

'CXX.0.A' - where "XX" designates the pipeline version used.

CXX.0POST44.A where "XX" designates the pipeline version used. |

NOTE :The 'CAMPAIGN' FITS header keyword lists the campaign number in SSC format.
To translate to IRS Team campaign numbers see : Campaign Numbers.

Long High (LH) data from campaign 25 onwards must be processed in SMART with a different set of Calibration files from those used for campaigns 1 - 24.
Long Low (LL) data from campaign 55 onwards must be processed in SMART with a different set of Calibration files from those used for campaigns 1 - 44.

Although the "CAL_SET" FITS header keyword changes for all data from all modules at both campaigns 25 and 45 only LH and LL modules are effected by the changes.

There was no change to LH at campaign 45, only LL was changed then.

SSC Conventions - LH Bias Change Time Dependent File Names

During the Spitzer (SIRTF) mission the bias voltage for the long high (LH = b3) detector was changed.
This change took place between observing campaigns 24 and 25.
For all sets of Calibration files distributed by SSC after the bias voltage change certain of the long high module files come in a matched pair,
one for observations taken before the bias voltage change and one for after.

File pair name example :

b3_flatfield_cmask_111111111_811265333.fits

b3_flatfield_cmask_813250569_1129732381.fits

Meaning of system clock time values :

|*System Clock Time*

Function
   
|111111111 |Chosen by SSC to be the lowest possible time that can be processed by their pipeline system.
It designates a time well before the start of the Spitzer (SIRTF) mission. | |811265333 |End of observing campaign 24.
Last campaign before long high bias voltage change. | |813250569 |Beginning of observing campaign 25.
First campaign after long high bias voltage change. | |1129732381 |Chosen by SSC to be the highest possible time that can be processed by their pipeline system.
It designates a time well after the end of the Spitzer (SIRTF) mission. |

Recent SSC releases have included certain files in sets of three. For example :

  1. b3_flatfield.fits
  2. b3_flatfield_111111111_811265333.fits
  3. b3_flatfield_813250569_1129732381.fits

  1. b3_flatfield_cmask.fits
  2. b3_flatfield_111111111_811265333_cmask.fits
  3. b3_flatfield_813250569_1129732381_cmask.fits

  1. b3_fluxcon.tbl
  2. b3_fluxcon_111111111_811265333.tbl
  3. b3_fluxcon_813250569_1129732381.tbl

In these cases the files are to be treated thus :

|*Time Range Designator*

Meaning
   
|111111111_811265333 |Used for processing all long high data up to and including Observing Campaign 24.
IE. All pre-LH bias voltage change observations. | |813250569_1129732381 |Used for processing all long high data from Observing Campaign 25 and later.
IE. All post-LH bias voltage change observations. | |No time range |When a file has no SCLK time range in its title AND it is accompanied by two other files
of the same name and type which do have SCLK time ranges in their titles
this file is a generic file ONLY to be used for calibration in those circumstances
where one of the other two (with SCLK time ranges) cannot be used.
IE. This file is unlikely to ever be used.
Its main function is in the SSC Pipeline only. |

For the LH module there are four pairs of files in the SMART sm_cal_sys_XX_X.idl Calibration Defaults file that are time dependent.
Their system variable names contain the string "bvc" for "bias voltage change".
"!sXX-X" denotes the SSC release version number. (EG. s15-3, etc.)
The defining IDL code is :

defsysv,'!sm_lh_bpm_f',!sm_cal_data +'mask/'+'irs_lh_bpm_!sXX-X.fits'
defsysv,'!sm_lh_bpm_bvc_post25_f',!sm_cal_data +'mask/'+'irs_lh_bpm-bvc-post25_!sXX-X.fits'

defsysv,'!sm_lh_flatfield_f',!sm_cal_data +'flat/'+'irs_lh_flatfield_!sXX-X.fits'
defsysv,'!sm_lh_flatfield_bvc_post25_f',!sm_cal_data +'flat/'+'irs_lh_flatfield-bvc-post25_!sXX-X.fits'

defsysv,'!sm_lh_fluxcon_f',!sm_cal_data +'flux/'+'irs_lh_fluxcon_!sXX-X.tbl'
defsysv,'!sm_lh_fluxcon_bvc_post25_f',!sm_cal_data +'flux/'+'irs_lh_fluxcon-bvc-post25_!sXX-X.tbl'

defsysv,'!sm_lh_pmask_f',!sm_cal_data +'mask/'+'irs_lh_pmask_!sXX-X.fits'
defsysv,'!sm_lh_pmask_bvc_post25_f',!sm_cal_data +'mask/'+'irs_lh_pmask-bvc-post25_!sXX-X.fits'

SSC Conventions - LL Bias Change Time Dependent File Names

During the Spitzer (SIRTF) mission the bias voltage for the long low (LL = b2) detector was changed.
This change took place between observing campaigns 44 and 45.
For all sets of Calibration files distributed by SSC after the bias voltage change certain of the long low module files come in a matched pair,
one for observations taken before the bias voltage change and one for after.

File pair name example :

b2_lincal.fits

b2_lincal_878083329_1129732381.fits

Meaning of system clock time values :

|*System Clock Time*

Function
   
|878083329 |Beginning of observing campaign 45.
First campaign after long low bias voltage change. | |1129732381 |Chosen by SSC to be the highest possible time that can be processed by their pipeline system.
It designates a time well after the end of the Spitzer (SIRTF) mission. |

Recent SSC releases have included certain files in sets of two. For example :

  1. b2_lincal.fits
  2. b2_lincal_878083329_1129732381.fits

In these cases the files are to be treated thus :

|*Time Range Designator*

Meaning
   
|878083329_1129732381 |Used for processing all long low data from Observing Campaign 45 and later.
IE. All post-LL bias voltage change observations. | |No time range |Used for processing all long low data up to and including Observing Campaign 44.
IE. All pre-LL bias voltage change observations. |

For the LL module there are four pairs of files in the SMART sm_cal_sys_XX_X.idl Calibration Defaults file that are time dependent.
Their system variable names contain the string "bvc" for "bias voltage change".
"!sXX-X" denotes the SSC release version number. (EG. s15-3, etc.)
The defining IDL code is :

defsysv,'!sm_ll_bpm_f',!sm_cal_data +'mask/'+'irs_ll_bpm_!sXX-X.fits'
defsysv,'!sm_ll_bpm_bvc_post45_f',!sm_cal_data +'mask/'+'irs_ll_bpm-bvc-post45_!sXX-X.fits'

defsysv,'!sm_ll_flatfield_f',!sm_cal_data +'flat/'+'irs_ll_flatfield_!sXX-X.fits'
defsysv,'!sm_ll_flatfield_bvc_post45_f',!sm_cal_data +'flat/'+'irs_ll_flatfield-bvc-post45_!sXX-X.fits'

defsysv,'!sm_ll_fluxcon_f',!sm_cal_data +'flux/'+'irs_ll_fluxcon_!sXX-X.tbl'
defsysv,'!sm_ll_fluxcon_bvc_post45_f',!sm_cal_data +'flux/'+'irs_ll_fluxcon-bvc-post45_!sXX-X.tbl'

defsysv,'!sm_ll_pmask_f',!sm_cal_data +'mask/'+'irs_ll_pmask_!sXX-X.fits'
defsysv,'!sm_ll_pmask_bvc_post45_f',!sm_cal_data +'mask/'+'irs_ll_pmask-bvc-post45_!sXX-X.fits'

Bias Change Files for IRS Disks Team / Rochester Group

For special processing purposes for the IRS Disks Team certain extra files are added to the SMART Calibration directories on the Cornell cluster.
When a bias voltage change is made these files must be duplicated with a "bvc-post" type name.
This is to assist setting relevant Calibration files.

The actual contents of the "bvc-post" files and their corresponding predecessor files is identical.
To make "bvc-post" files simply copy and re-name pre-existing ones.

Files to make for every bias voltage change :

  1. Under "mask/", the "irs_mm_bpm-bvc-postcc_e3.fits" files,
    where "mm" is the module having its bias changed and "cc" is the campaign in which it changes.

    For example :

    1. irs_ll_bpm-bvc-post45_e3.fits (can be copied from irs_ll_bpm_e3.fits)
    2. irs_lh_bpm-bvc-post25_e3.fits (can be copied from irs_lh_bpm_e3.fits)
  2. Under "flux/", the "irs_mm_fluxcon-bvc-postcc_s1.tbl" files,
    where "mm" is the module having its bias changed and "cc" is the campaign in which it changes.

    For example :

    1. irs_ll_fluxcon-bvc-post45_s1.tbl (can be copied from irs_ll_fluxcon_s1.tbl)
    2. irs_lh_fluxcon-bvc-post25_s1.tbl (can be copied from irs_lh_fluxcon_s1.tbl)

 
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