OGIP Memo OGIP/93-013

Standard Strings for Mission, Instrument, Filter, Detector & Grating Names for OGIP FITS files
Ian M George
Lorella Angelini
& Michael F. Corcoran
Code 662,
MD 20771

Version: 2012 Oct 10


We give a list of standard character strings used within the OGIP for the specification of the Mission, Instrument, Filter, Detector & Grating in use.


Release Sections Changed Brief Notes
1993 Jan 13 First (internal) Draft
1994 Oct 14 All Major revision to all strings
1994 Nov 19 All Made compatible with LaTeX2HTML software
1995 Jan 17 HEAO-1/A-4 Added instrument sub-strings for HEAO-1/A-4
1995 Jan 26 OSO-8 Added instrument sub-strings for OSO-8/GCXSE
1995 Feb 17 SAC-B Added mission/instrument names
1995 Feb 27 Ariel-V Added acronyms for Expts A & F
1995 Mar 03 1.5, Einstein & EXOSAT Added Grating Definitions
1995 Mar 06 SAS-2 Revised instrument names
2006 Feb 17 (MFC) Added Chandra, XMM-Newton, Swift, Suzaku, GLAST, HETE-2; merged Table 1 (instrument name) & Table 2 (detector name); removed SAC-B; added html links to mission web pages; convert tables to longtables
2011 Mar 30 (MFC) Table 2 include Fermi as an alias for GLAST
2012 Oct 10 (MFC) Table 2 include NuSTAR


    1.1  FITS Keywords
    1.2  Design Criteria
    1.3  Case-Sensitivity
    1.4  Specification of multiple instruments & detectors
    1.5  Filters/Gratings in the Optical Path
    1.6  Contacts
    2.1  Standard Values for Satellite Missions & Instruments
    2.2  Standard Values for Instrument Filters
    2.3  Standard Values for Gratings

List of Tables

    1  FITS Identification Keywords
    2  Standard Strings for TELESCOP, INSTRUME & DETNAM
    3  OGIP Standard Strings for Filters
    4  Summary of Standard Strings for Gratings used within the OGIP


In order to facilitate interpretation of archived FITS datasets by software and users, the Office of Guest Investigator Programs (OGIP) at NASA/GSFC and the High Energy Astrophysics Science Archive Research Center (HEASARC) FITS Working Group (OFWG) have adopted a standard set of FITS header keywords and keyword values to be used to uniquely specify the Mission, Instrument and Detector to which the dataset refers, and to specify any Filter and/or Grating in use. This memo lists those currently in use.

1.1  FITS Keywords

The following FITS keywords are used to provide information regarding the provenance of the dataset:
Table 1: FITS Identification Keywords
FITS Keyword Meaning Reference
TELESCOP observatory or mission; for space science, usually refers to the spacecraft on which various instruments are mounted NOST Standard
INSTRUME refers to a particular instrument system contained on TELESCOP NOST Standard
DETNAM identifies the detector subsystem (for example, the CCD chip in an array) this document
FILTER identifies the filter in front of the particular instrument or detector this document
GRATING identifies the particular grating which may be interposed in the optical path this document
In the table above, the NASA Office of Science and Technology (NOST) Standard is the "Definition of the Flexible Image Transport System (FITS)", March 29, 1999 (NOST 100-2.0).

1.2  Design Criteria

During the development of these standard strings we decided against deriving a standard-recipe (set of rules) for specifying all the necessary information for all missions, instruments etc. This decision was primarily based on the great variety of instrumentation handled by the OGIP. Instead we considered it preferable to define the minimum number of unique strings which served the purpose of identificaton, and wherever possible adopting the strings in common use by instrument teams & scientists.
Values already in widespread use for the mandatory FITS keywords TELESCOP and INSTRUME also influenced our decision in some cases.
In almost all cases, the Mission and Filter strings are fairly obvious (& uncontroversial), thus are straightforward to define. It is likely that these strings will most often be used as the values of the TELESCOP & FILTER keywords in FITS files.
The character strings adopted for the specification of the instrument/detector/grating (and, where necessary, sub-detector) are naturally highly instrument-specific. These strings will most often be used as the values of the INSTRUME & DETNAM or INSTRUME & GRATING keywords in FITS files.
It should be noted that many of the strings specified in the following sections are provided solely to enable calibration datasets to be fully specified.

1.3  Case-Sensitivity

All the strings listed in the following sections should be considered case-sensitive. However, reliance on case to distinguish different values of TELESCOP, INSTRUME, DETNAM, FILTER or GRATING is deprecated.

1.4  Specification of multiple instruments & detectors

Under certain circumstances it may be desirable to combine data from different instruments and/or different parts (sub-detectors) of a given instrument together in a single FITS dataset (eg. combining ASCA GIS2 and GIS3 datasets, combining the Argon layers of detector modules DET-A and DET-B for the EXOSAT ME). It is crucial that the INSTRUME and/or DETNAM keywords reflect such combinations, to inform the user and reduction or analysis software.
There are two ways in which such combinations are specified via the INSTRUME and/orDETNAM keywords:
  1. Certain common combinations are given their own unique values
    For example:
    • For the EXOSAT ME
      INSTRUME= 'ME       '
      DETNAM  = 'QUADj XX'
      is used to denote that quadrant j of the 8 ME modules have been combined (with j=1 representing DET-A + DET-B, j=2 representing DET-C + DET-D etc).
  2. The INSTRUME and/or DETNAM keyword strings for less common combinations are constructed using the standard strings listed in this document separated by a comma (,).
    For example:
    • For a combination of the two ASCA GIS experiments

1.5  Filters/Gratings in the Optical Path

Some instrument/detector combinations can operate in conjunction with a filter or grating inserted into the optical path. Often the usage of such a grating is optional, and observations can also be carried out using the detector without the grating in place. In the past, the instrument/grating combination has often been referred to as a 'separate' instrument. For example, data taken when the moveable transmission grating was in the optical path of one of the two low energy telescopes on EXOSAT was commonly referred to as being obtained from the 'EXOSAT TGS1' or 'EXOSAT TGS2' instrument. However, this procedure is strongly discouraged since if different gratings could be associated with the same or different focal plane instruments, different acronyms would need to be defined for each instrument/grating combination.
Instead, the OGIP recommends that the focal plane instrument be specified by the INSTRUME keyword, and that the filter or grating be specified by the the FILTER or GRATING keywords, respectively.
For example:
INSTRUME= 'CMA1       '
GRATING = 'TGS1       '

TELESCOP= 'CHANDRA '           / Telescope
INSTRUME= 'ACIS    '           / Instrument
GRATING = 'HETG    '           / Grating

1.6  Contacts

Please send any comments or suggestions to the General HEASARC Feedback mailing list from the HEASARC Feedback page, http://heasarc.gsfc.nasa.gov/cgi-bin/Feedback


2.1  Standard Values for Satellite Missions & Instruments

Table 2: Standard Strings for TELESCOP, INSTRUME & DETNAM
Observatory Name TELESCOP INSTRUME DETNAM Comments
Table 3: (continued)
Observatory Name TELESCOP INSTRUME DETNAM Comments
aFocal plane Instrument
bOptical path might include a grating; see Table 2.3
cOptical path might include a filter; see Table 3
Ariel-V ARIEL-V SSI DETiXX SSI= Sky Survey Instrument; i=number of detector module; XX either AA or XE for Argon or Xenon layer respectively; if XX not given then both layers
ASM ASM = All Sky Monitor (Expt G)
RMC Rotation Modulation Collimator (Expt A)
ST Scintillation Telescope (Expt F)
Advanced Satellite for Cosmology and Astrophysics (Formerly ASTRO-D) ASCA XRT-i Qj X-ray Telescope module (i=1,2,3,4); Qj refers to the jth quadrant (j=0,1,2,3) of XRT-i
GISi Gas Imaging Spectrometer (i=2,3)
SISi CCDj Solid State Imaging Spectrometer (i=0,1); CCDj refers to the CCD chip number (j=0,1,2,3)
Broad-Band X-ray Telescope BBXRT XRT-a X-ray Telescope module (a=A,B)
Aia Detector-A pixel (i=0,1,..5)
Bia Detector-B pixel (i=0,1,..5)
Chandra X-ray Observatory CHANDRA, AXAF ACISa ACIS-a Advanced CCD Imaging Spectrometer; a is a string giving the array of CCD chips that are turned on (for example; ACIS-1; ACIS -01236; etc.; or a=I or S for the imaging or spectroscopic array
HRCa HRC-b High Resolution Camera; b is either "I" (for the imaging array), "S", for the spectroscopic array, or "S-i" (where i is either 1,2,3)
EPHIN NONE Electron Proton Helium Instrument
PCAD ACA-P Pointing Control and Aspect Determination System; Aspect Camera Assembly
RWA Reaction Wheel Assembly (?)
IRU Inertial Reference Unit
TEL HRMA Telescope; High Resolution Mirror Assembly
See the ASC FITS File Designer's Guide by MacDowell & Rots for additional information
Compton Gamma-Ray Observatory CGRO, GRO, COMPTON BATSE LAD-i Burst and Transient Source Experiment; Large Area Detector; i=0,1,2,7
LADB Burst-selected LAD detectors
SD-i Spectroscopy Detector; i=0,1,2,7
SDB Burst-selected SDs
COMPTEL D1 -i Imaging Compton Telescope; Liquid scintillator Detector; i=1,2,7
D2 -j Imaging Compton Telescope; NaI Detector; j=1,2,14
EGRET Energetic Gamma-ray Experiment Telescope
OSSE OSSE-i Oriented Scintillation Spectrometer Experiment; independently-pointable scintillator i, i=1,2,3,4
COS-B COS-B COS-B COS-B COS-B spark chamber
Extreme Ultraviolet Explorer EUVE DSSc Deep Survey/Spectrometer
European X-ray Observatory Satellite EXOSAT LEIT-ib Low-Energy Imaging Telescope (i=1,2)
CMA-ia Channel Multiplier Array (i=1,2)
PSD-ia Position Sensitive Detector (i=1,2)
GSPC Gas-Scintillation Proportional Counter
ME DET-x XX Medium Energy Proportional Counter array; x=A,B,C,....H; XX = AR or XE for Argon or Xenon layer respectively; XX not present: both layers)
QUADi XX ME quadrant; i=1, DET-A + DET-B etc; rules for XX as above)
HALFi XX ME half; i=1, QUAD1 + QUAD2 etc; rules for XX as above
CORN XX ME corner detectors ie DET-A, DET-D, DET-E & DET-G); (rules for XX as above)
ALL XX All eight ME detectors (DET-A + DET-B ... DET-G);
(rules for XX as above)
Fermi Gamma-Ray Space Telescope GLAST, FERMI GBM NAI_YY Gamma-Ray Burst Monitor; NAI= sodium iodide detector; YY=00 to 11
BGO_ZZ BGO= Bismuth Germanate; ZZ=00 to 01
LAT Large Area Telescope
ACD Anti-coincidence detector
GINGA (Japanese for "Galaxy"; formerly ASTRO-C) GINGA LAC XX Large Area proportional counter; XX = TOP or MID for Argon or Xenon layer respectively; XX not present: both layers
ASM All-Sky Monitor
GBD Gamma-ray Burst Detector
High Energy Astrophysical Observatory #1 HEAO-1 HEAO-A A-1 Large Area Sky Survey Expt
A-2 LED-i x Cosmic X-ray Expt; Low Energy Detector; i=1,2 x=s,l
MED x Medium Energy Detector; x=s,l
HED-i x High Energy Detector; i=1,2,3 x=s,l
A-3 Scanning Modulation Collimator
A-4 LED-i The A-4 High Energy Experiment; Low Energy Detector;i=3,6
MED-i Medium Energy Detector; i=1,2,4,5
HED-7 High Energy Detector
High Energy Astrophysical Observatory-2 EINSTEIN, HEAO-2, HEAO-B HRMAb High Resolution Mirror Assembly
FPCSa PET Focal Plane Crystal Spectrometer; PET for pentaerythritol diffractor
ADP ammonium dihydrogen phosphate diffractor
TAP thalium acid phthalate diffractor
RAP rubidium acid phthalate diffractor
PbL lead laurate diffractor
PbSt for lead sterate diffractor
HRI-ia High Resolution Imager (i=1,2,3)
IPC-ia Imaging Proportional Counter (i=1,2)
SSS-ia Solid-State Spectrometer (i=1,2)
MPC Monitor Proportional Counter
High Energy Transient Experiment #2 HETE-2, HETE SXC Soft X-ray Camera
WXM Wide-Field X-ray Monitor
FREGATE French Gamma Telescope
International Gamma-Ray Astrophysics Laboratory INTEGRAL SPI Spectrometer on INTEGRAL
IBIS ISGRI Imager on Board the Integral Satellite; ISGRI is a CdTe array
PICSIT PICSIT is a CsI array
JMXN Joint European X-Ray Monitor; N=1,2
OMC Optical Monitoring Camera
International Ultraviolet Explorer IUE FES-ia (Optical) Fine Error Sensor (i=1,2)
LWPa Long Wavelength Prime Camera
LWRa Long Wavelength Redundant Camera
SWPa Short Wavelength Prime Camera
SWRa Short Wavelength Redundant Camera
Nuclear Spectroscopic Telescope Array   NUSTAR FPM Focal Plane Monitor
Orbiting Solar Observatory #8 OSO-8, OSO-I UVS High-resolution UV spectromter
MUVS Multichannel UV & visible spectrometer
CGCS Columbia Grating Crystal spectrometer
CXP-i Columbia X-ray Polarimeter (i=1,2)
XHE X-ray Heliometer
WSXE Wisconsin Soft X-ray Experiment
GCXSE DET-X Goddard Cosmic X-ray Spectrometer Experiment; Detector module (X=A, B or C)
HECXE High-energy celestial X-ray Experiment
EUV Extreme UV experiment
Röntgen Satellite ROSAT XRT X-ray Telescope
HRIa High Resolution Imager
PSPCxa Position Sensitive Proportional Counter (x=B,C flown)
WFCc Wide Field Camera
Rossi X-ray Timing Explorer XTE, RXTE ASM All-sky monitor
HEXTE PWai The High Energy X-ray Timing Experiment; Phoswich Detector Identifier (a=A,B; i=0,1,2,3)
PCA PCUi Proportional Counter Array; Proportional Counter Unit (i=0,1,2,3,4)
Small Astronomy Satellite #2 SAS-2, SAS-B SC Spark Chamber
PC Proportional Counter
Small Astronomy Satellite #3 SAS-3, SAS-C XRT-i X-ray Telescope i of LED experiment (i=1,2)
LED-ia Low Energy Detector i (i=1,2)
RMC Rotating Modulation Collimator experiment
SCD-i XX Slat Collimator Detector i, layer XX,(i=1,2, XX=AR,XE)
Suzaku SUZAKU, Astro-E2 HXD WELL-GSO Hard X-ray Detector
XISN X-ray Imaging Spectrometer; N=0,1,2, or 3
XRSc PIXNN X-ray Spectrometer; NN=00,01,02,... 31
XRT, XRT-a X-ray Telescope; a is either "I" or "S" for imaging or spectroscopy detectors, respectively.
Swift SWIFT BAT Burst Alert Telescope
UVOTAb,c Ultraviolet & Optical Telescope
SC General Spacecraft information
XRT X-ray Telescope
Vela 5B VELA 5B XC Vela=watchman in Spanish; All-sky monitor
XMM-Newton XMM EMOSna,b,cEuropean Photon Imaging Camera (EPIC): Metal-Oxide-Silicon CCD; n=1,2
OMa,b,c Optical Monitor
RGSc RGA Reflection Grating Spectrometer; Reflection Grating Assembly
RFCb RGS Focal Camera

2.2  Standard Values for Instrument Filters

Table 4: OGIP Standard Strings for Instrument Filters
Table 5: (continued)
Any Any Any (blank) No filter in use; similar if FILTER keyword missing from file
Any Any NONE, OPEN Filter in open position
Chandra ACIS ACIS-n UVIS_ACISI n=0,1,2... 9
EINSTEIN(f.plane inst) AL (BBFS) Aluminium
BE (BBFS) Beryllium
EXOSAT LEIT CLOSED Totally opaque filter (FW Pos 1)
PPL Polypropylene (FW Pos 2)
4Lx Thick (400 nm) Lexan (FW Pos 3)
Fe Cal Fe55 source (FW Pos 5)
Al/P Aluminium-parylene (FW Pos 6)
3Lx Thin (300 nm) Lexan (FW Pos 7)
Bor Boron (FW Pos 8)
UV Magnesium Fluoride (FW Pos 9)
WFC S1x C/Lexan/Bor Survey filter (x=a,b)
S2x Be/Lexan Survey filter (x=a,b)
P1 Al/Lexan Pointed phase filter
P2 Sn/Al Pointed phase filter
GOLD Gold (Foils)
RED_AP Reduced Aperture filter wheel position
XMM EMOSnThin n=1,2
EPN Thin
RGS Thin

2.3  Standard Values for Gratings

Table 6: Summary of Standard Strings for Gratings used within the OGIP

ANY ANY NONE No grating used
Chandra Any focal plane instrument HETG High Energy Transmission Grating
LETG Low Energy Transmission Grating
EINSTEIN Any focal plane instrument OGS/Gj Objective Grating Spectrometer (j=5,10) (used with HRI-i in the focal plane)
EXOSAT LEIT TGSi Transmission Grating Spectrometer (i=1,2) (used with CMAi in f.plane)


We thank the numerous people both inside and outside the OGIP who have contributed suggestions & comments to this document. In particular we thank Jonathan McDowell (CfA) for sharing his great knowledge of previous missions. Jonathan's Space Report is an excellent resource on past and current space missions.


File translated from TEX by TTH, version 3.85.
On 10 Oct 2012, 16:57.