MRTCAL tutorial. IRAM Science Software User Meeting Apr , St Martin d Hères

Transcription

1 MRTCAL tutorial Presentation by Sébastien BARDEAU, Jérôme PETY & Albrecht SIEVERS (IRAM) Current MRTCAL developers: Sébastien BARDEAU, Albrecht SIEVERS & Jérôme PETY IRAM Science Software User Meeting Apr , St Martin d Hères

2 Indexing IMB-FITS files: I. From raw data files mrtcal/data> ls -l total 20 drwx bardeau astro 4096 Apr 5 15: drwx bardeau astro 4096 Apr 5 15: drwx bardeau astro 4096 Apr 5 15: drwx bardeau astro 4096 Apr 5 15: drwx bardeau astro 4096 Apr 5 15:55 12t00 mrtcal/data> ls -l */*.fits -rw bardeau astro Nov /iram30m-4mhz s200-imb.fits -rw bardeau astro Dec /iram30m-4mhz s201-imb.fits -rw bardeau astro Dec /iram30m-fts s200-imb.fits -rw bardeau astro Dec /iram30m-fts s201-imb.fits -rw bardeau astro Feb /iram30m-fts s233-imb.fits -rw bardeau astro Nov /iram30m-fts s234-imb.fits -rw bardeau astro Dec /iram30m-wilma s200-imb.fits -rw bardeau astro Dec /iram30m-wilma s201-imb.fits -rw bardeau astro Dec /iram30m-fts s204-imb.fits -rw bardeau astro Dec /iram30m-fts s205-imb.fits -rw bardeau astro Dec /iram30m-fts s100-imb.fits -r bardeau astro Mar /iram30m-fts s101-imb.fits -rw bardeau astro Jun /iram30m-fts s100-imb.fits -rw bardeau astro Jun /iram30m-fts s101-imb.fits -rw bardeau astro Jun /iram30m-fts s102-imb.fits -rw bardeau astro Jun /iram30m-fts s103-imb.fits -rw bardeau astro Jun /iram30m-fts s104-imb.fits -rw bardeau astro Jun /iram30m-fts s105-imb.fits -rw bardeau astro Jun /iram30m-fts s212-imb.fits...

3 Indexing IMB-FITS files: II. To easy-to-use index # N.V ProjId Source Date UT Scn Backe ObsType Swi Calibr CONTROLD 30-SEP :52: MHZ CALIBRATE PSW NONE CONTROLD 30-SEP :52: WILMA CALIBRATE PSW NONE CONTROLD 30-SEP :52: FTS CALIBRATE PSW NONE CONTROLD 30-SEP :53: MHZ TRACKED PSW NONE CONTROLD 30-SEP :53: WILMA TRACKED PSW NONE CONTROLD 30-SEP :53: FTS TRACKED PSW NONE t00-11 W3OH 30-NOV :03: FTS CALIBRATE PSW NONE t00-11 W3OH 30-NOV :04: FTS TRACKED WSW NONE HORSEHEAD 28-JAN :37: FTS CALIBRATE PSW NONE HORSEHEAD 28-JAN :38: FTS TRACKED PSW NONE HORSEHEAD 09-AUG :39: FTS CALIBRATE PSW NONE HORSEHEAD 09-AUG :39: FTS ONTHEFLYMAP PSW NONE CHAIN-1 03-JUN :50: VESPA CALIBRATE PSW NONE CHAIN-1 03-JUN :50: FTS CALIBRATE PSW NONE CHAIN-1 03-JUN :50: VESPA TRACKED FSW NONE CHAIN-1 03-JUN :50: FTS TRACKED FSW NONE CHAIN-1 03-JUN :52: VESPA TRACKED FSW NONE CHAIN-1 03-JUN :52: FTS TRACKED FSW NONE CHAIN-1 03-JUN :53: VESPA TRACKED FSW NONE CHAIN-1 03-JUN :53: FTS TRACKED FSW NONE...

4 Indexing IMB-FITS files: III. Goals and features Goals: Avoid re-reading IMB-FITS file each time, Fast search through IMB-FITS files, Bookkeeping of key parameters (see below), Database of calibration products (statistics, success/error status,...) Features: Fast: Read only a small part of the file at index time, entries updated only when needed. Robust: Can index aborted scans or even empty (0-sized) files. Simple: e.g., one command indexes a whole directory tree recursively. Tunable: Various options for custom indexing (e.g., restricted access to the IMBFITS files) Under control: Index file uses in-house binary format (CLASSIC Data Container).

5 Indexing IMB-FITS files: IV. Building Procedure in file pro/demo-index.cal Make or remake (overwrite) a new index from scratch: MRTCAL> index build I-FILE, File is version 2 (record length: 400 words) I-INDEX>WRITE, Created file index.mrt indexing 8 files Default index file name is index.mrt (CLASSIC Binary Container). Same operation recursively (each directory gets its own index file): MRTCAL> index build /recursive I-FILE, File is version 2 (record length: 400 words) I-INDEX>WRITE, Created file./12142/index.mrt indexing 28 files I-FILE, File is version 2 (record length: 400 words) I-INDEX>WRITE, Created file./09054/index.mrt indexing 8 files I-FILE, File is version 2 (record length: 400 words) I-INDEX>WRITE, Created file./12t00/index.mrt indexing 6 files...

6 Indexing IMB-FITS files: V. Updating Index new scans or new subscans in incomplete scans: MRTCAL> index update I-INDEX>WRITE, Unmodified file index.mrt indexing 8 files Simulate an update: MRTCAL> sic rename iram30m-fts s234-imb.fits iram30m-fts s234-imb.fits.bak MRTCAL> index build I-FILE, File is version 2 (record length: 400 words) I-INDEX>WRITE, Created file index.mrt indexing 7 files MRTCAL> sic rename iram30m-fts s234-imb.fits.bak iram30m-fts s234-imb.fits MRTCAL> index update I-INDEX>WRITE, Updated file index.mrt indexing 8 files (including 1 new) Same operation recursively (each directory gets its own index file udpated): MRTCAL> index update /recursive I-INDEX>WRITE, Unmodified file./12142/index.mrt indexing 28 files I-INDEX>WRITE, Unmodified file./09054/index.mrt indexing 8 files I-INDEX>WRITE, Unmodified file./12t00/index.mrt indexing 6 files...

7 Indexing IMB-FITS files: VI. Watching Real-time indexing, i.e., wait until new data is coming (e.g., at the telescope). MRTCAL> sic dir MRTCAL> index build I-FILE, File is version 2 (record length: 400 words) I-INDEX>WRITE, Created file index.mrt indexing 8 files MRTCAL> index watch (wait until new data appears or CTRL-C) (mimic new data by touching an empty file e.g. touch iram30m-4mhz s999-imb.fits) I-INDEX>WRITE, Updated file index.mrt indexing 9 files (including 1 new, 1 unreadable) MRTCAL>! Command flow is resumed right after

8 Indexing IMB-FITS files: VII. Contents Index contents (for each IMB-FITS): Telescope identifier, Source name, Project identifier, Observing date, UT, LST (typical), Azimuth and elevation (typical), Longitude, Latitude, System of coordinates, Equinox, Receiver name(s), Scan number, Backend name (always 1 backend per IMB-FITS), Observing type (e.g., tracked, On-The-Fly,...), Switching mode (e.g., frequency switching, position switching,...) Polarization status (file contains polarimetry data or not), File status (i.e., unreadable, empty, incomplete, complete), Calibration status (i.e. none, done, failed) Indexing time (for bookkeeping). + some additional bookkeeping data after calibration (see later)

9 Browsing through index files: I. Overview Same philosophy as in CLASS: 1. Open an INPUT index. 2. Setup the CURRENT index. 3. Work either on the full index or on a single index entry.

10 Browsing through index files: II. Opening index file(s) Index is opened and built in memory with: MRTCAL> index open I-INDEX, 8 entries in Input index Implicit after a build or update: MRTCAL> index build I-FILE, File is version 2 (record length: 400 words) I-INDEX>WRITE, Created file index.mrt indexing 8 files I-INDEX, 8 entries in Input index Same operation recursively: MRTCAL> sic dir.. MRTCAL> index open /recursive I-INDEX, 46 entries in Input index several files index.mrt on disk, but single Input index in memory (merged and sorted).

11 Browsing through index files: III. Selecting Procedure in file pro/demo-mlist.cal The current index is built from opened index(es) with the command MFIND: MRTCAL> sic dir MRTCAL> mfind! Select everything I-FIND, 46 entries in Current index Use options to select a custom subset, e.g.: MRTCAL> mfind /source CONTROLD /date 30-SEP-2010 /backend FTS I-FIND, 2 entries in Current index Possible selectors: - /DATE: by date (or list of dates), - /SCAN: by scan (or list of scans), - /BACKEND: by backend name, - /FRONTEND: by receiver name, - /OBSTYPE: by observing type (or list of types), - /SWITCHMODE: by switching mode (or list of modes), - /SOURCE: by source name, - /PROJID: by project identifier, - /COMPLETENESS: YES, NO, READABLE, UNREADABLE - /CALIBRATED: NONE, DONE, FAILED

12 Browsing through index files: III. Listing Default list: MRTCAL> mlist # N.V ProjId Source Date UT Scn Backe ObsType Swi Calibr CONTROLD 30-SEP :52: FTS CALIBRATE PSW NONE CONTROLD 30-SEP :53: FTS TRACKED PSW NONE Custom list. Many possible columns, see HELP MLIST /COLUMN for details: MRTCAL> mlist /column? I-MLIST, Choices are: NUMBER ENTRY DIRECTORY FITSFILE MRTFILE RECORD WORD VERSION TELESCOPE PROJID SOURCE OBSERVED UT LST AZIMUTH ELEVATION POSITION FRONTEND SCAN BACKEND OBSTYPE SWITCHMODE POLARIMETRY COMPLETE CALIBRATED ITIME ISLAST WITH MRTCAL> mlist /column fitsfile backend frontend FITSFILE BACKE FRONTEND iram30m-fts s200-imb.fits FTS E090 E150 iram30m-fts s201-imb.fits FTS E090 E150

13 Browsing through index files: IV. Listing (cont d) Table-Of-Contents: /TOC option MRTCAL> mfind I-FIND, 8 entries in Current index MRTCAL> mlist /toc Number of observation dates 2 30-SEP ( 75.0%) 28-JAN ( 25.0%) Number of scans ( 37.5%) ( 37.5%) ( 12.5%) ( 12.5%) Number of setups SEP ( 37.5%) 30-SEP ( 37.5%) 28-JAN ( 12.5%) 28-JAN ( 12.5%)

14 Browsing through index files: V. Listing (cont d) Result of MLIST /TOC is saved in a SIC structure variable: MRTCAL> exa mtoc% MTOC%! Structure GLOBAL MTOC%SETUP is a character* 12 Array of dimensions 4 2 MTOC%MSETUP is a long integer Array of dimensions 4 MTOC%NSETUP = 4! Long GLOBAL MTOC%SCAN is a character* 12 Array of dimensions 4 MTOC%MSCAN is a long integer Array of dimensions 4 MTOC%NSCAN = 4! Long GLOBAL MTOC%OBS is a character* 12 Array of dimensions 2 MTOC%MOBS is a long integer Array of dimensions 2 MTOC%NOBS = 2! Long GLOBAL MRTCAL> exa mtoc%obs MTOC%OBS is a character* 12 Array of dimensions 2 30-SEP JAN-2012 useful to build procedures around your dataset, e.g., loop on sources, or dates, or combination of backend+switching mode...

15 Browsing through index files: VI. Listing (cont d) Custom Table-Of-Contents: MRTCAL> mlist /toc? I-TOC, Choices are: NUMBER VERSION TELESCOPE ID SOURCE OBSERVED FRONTEND SCAN BACKEND OBSTYPE SWITCHMODE POLARIMETRY CALIBRATED DIRECTORY MRTCAL> mlist /toc source backend Number of sources... 2 CONTROLD 6 ( 75.0%) HORSEHEAD 2 ( 25.0%) Number of backends MHZ 2 ( 25.0%) WILMA 2 ( 25.0%) FTS 4 ( 50.0%) Number of setups... 4 CONTROLD 4MHZ 2 ( 25.0%) CONTROLD WILMA 2 ( 25.0%) CONTROLD FTS 2 ( 25.0%) HORSEHEAD FTS 2 ( 25.0%)

16 Calibrating: I. One by one Procedure in file pro/demo-calibrate.cal Setup the IMB-FITS files to be calibrated, and the CLASS file where the spectra are saved: MRTCAL> mfind /source CONTROLD /backend WILMA I-FIND, 2 entries in Current index MRTCAL> ml # N.V ProjId Source Date UT Scn Backe ObsType Swi Calibr CONTROLD 30-SEP :52: WILMA CALIBRATE PSW NONE CONTROLD 30-SEP :53: WILMA TRACKED PSW NONE MRTCAL> file out controld-wilma.30m single /overwrite! The CLASS command for a new file Calibration scan alone: MRTCAL> calibrate 2! Calibration scan alone Calibrating CONTROLD 30-SEP :52: WILMA CALIBRATE PSW NONE... Science scan alone (reuse previous calibration scan from memory): MRTCAL> calibrate 5 Calibrating CONTROLD 30-SEP :53: WILMA TRACKED PSW NONE With CONTROLD 30-SEP :52: WILMA CALIBRATE PSW DONE... Or specify explicitly the calibration scan to be used (reprocess if needed): MRTCAL> calibrate 5 /with 2

17 Calibrating: II. Pipeline mode Pipeline mode: calibrate all science scans with all calibration scans of the current index. MRTCAL> mfind /source CONTROLD /backend WILMA! Build the current index I-FIND, 2 entries in Current index MRTCAL> file out controld-wilma.30m single /overwrite I-FILE, File is version 2 (record length: 1024 words) I-NEWPUT, controld-wilma.30m initialized MRTCAL> pipeline Welcome to the MRTCAL pipeline! [...] Working on current index [...] Successfully processed 2 entries, 0 errors (total 2 in index) Pipeline executed in seconds The MRTCAL pipeline wishes you a pleasant day! Automatic choice of the calibration scan: previous successful, more possibilities (like nearest neighbor or interpolation between neighbor) in the future. Robust: Failures are skipped and memorized in the index for later analysis (MFIND /CALIBRATED FAILED)

18 Saved calibration results: I. In the index Procedure in file pro/demo-products.cal After processing, the index entries are updated (new versions). Before: MRTCAL> mlist # N.V ProjId Source Date UT Scn Backe ObsType Swi Calibr CONTROLD 30-SEP :52: WILMA CALIBRATE PSW NONE CONTROLD 30-SEP :53: WILMA TRACKED PSW NONE After: MRTCAL> mfind /source CONTROLD /backend WILMA! Find the latest version MRTCAL> mlist # N.V ProjId Source Date UT Scn Backe ObsType Swi Calibr CONTROLD 30-SEP :52: WILMA CALIBRATE PSW DONE E1VLI:145 E0VLI: CONTROLD 30-SEP :53: WILMA TRACKED PSW DONE Plus: calibration scans: calibration results (Tsys and opacities as a function of frequency) for bookkeeping, science scans: which calibration scan was paired and how (under progress).

19 Saved calibration results: I. As CLASS Associated Arrays Default is to save calibration products under source calsky + Associated arrays: MRTCAL> mset output calibration associated! Default (calibration) MRTCAL> file in controld-wilma.30m! CLASS command MRTCAL> find! CLASS command I-FIND, 8 observations found MRTCAL> list /toc source! CLASS command Current index contains: Number of sources... 2 CALSKY 4 ( 50.0%) CONTROLD 4 ( 50.0%) MRTCAL> find /source CALSKY MRTCAL> get f MRTCAL> dump [...] ASSOCIATED ARRAYS Number of associated arrays: 7 Associated array #1: CALAMBIENT Associated array #2: CALCOLD Associated array #3: TREC Associated array #4: TCAL Associated array #5: TSYS Associated array #6: TAUZEN Associated array #7: FLAG

20 Tweaking MRTCAL behavior: I. Summary MRTCAL> msetup Setups Input (command READ) Read good and bad dumps from the backendxxx tables Use hardware chunk width Read the on-track part of the DATA column Do not intersect the subscan DATE-OBS and DATE-END with the tables MJD ranges Read non- and polarimetric chunks (NONE, AXIS, REAL, IMAG) DATA column is mapped into chunks at read time Bookkeeping Buffer space set to 512 MB Calibration (command CALIBRATE or PIPELINE) Read only good dumps from the backendxxx tables Calibration bandwidth set to 20.0 MHz (or hardware width when narrower) Chopper calibration engine runs in strict mode (any problem blanks the data) Give calibration feedback for every chunkset Calibration interval set to 20.0 minutes Do not intersect the subscan DATE-OBS and DATE-END with the tables MJD ranges Use time-nearest off subscan Ignore cross-polarimetric chunks (REAL, IMAG), calibrate the others (NONE, AXIS) Use previous calibration scan Interpolate Tsys values as a function of frequency...

21 Tweaking MRTCAL behavior: II. Summary (cont d) MRTCAL> msetup... Output Write calibration products in separated observations Write one spectrum per chunkset Accumulate dumps along every SCAN Write spectra in the CLASS output file Do not write the very experimental MRTCAL user section Do not write calibration results in VO XML Pipeline Continue to iterate with the next scan when an error is raised on the current scan Debug IMBFITS: (not implemented) INDEX: Allocation F, Others F CALIBRATION: Allocation F, Bookkeeping F, Others F OUTPUT: Accumulation F SYNCHRONIZATION: F

22 Tweaking MRTCAL behavior: III. Calibration bandwidth Procedure in file pro/demo-bandwidth.cal msetup calibration bandwidth 0.0 msetup calibration tsys nearest red line msetup calibration bandwidth 20.0 msetup calibration tsys nearest green line msetup calibration bandwidth 20.0 msetup calibration tsys linear blue line

23 Support of various observing modes Procedure in file pro/demo-process-all.cal MRTCAL> index build /recursive MRTCAL> mfind MRTCAL> mlist /toc id /var mytoc MRTCAL> for iid 1 to mytoc%nid MRTCAL: mfind /proj mytoc%id[iid] (calibration)... MRTCAL: next iid MRTCAL> mfind I-FIND, 46 entries in Current index MRTCAL> mlist /toc calibrated Number of calib status. 3 DONE 44 ( 95.7%) EMPTY 1 ( 2.2%) FAILED 1 ( 2.2%) Number of setups... 3 DONE 44 ( 95.7%) EMPTY 1 ( 2.2%) FAILED 1 ( 2.2%) MRTCAL> mfind /calibrated failed The demo dataset contains: : tracked position switch t00-11: tracked wobbler switch : tracked position switch : on-the-fly position switch : tracked and on-the-fly frequency switch t00-12: tracked wobbler switch

24 FITS reader: I. Reading Procedure in file pro/demo-read.cal MRTCAL> index open I-INDEX, 8 entries in Input index MRTCAL> mfind I-FIND, 8 entries in Current index MRTCAL> mlist # N.V ProjId Source Date UT Scn Backe ObsType Swi Calibr CONTROLD 30-SEP :52: MHZ CALIBRATE PSW NONE CONTROLD 30-SEP :52: WILMA CALIBRATE PSW NONE CONTROLD 30-SEP :52: FTS CALIBRATE PSW NONE CONTROLD 30-SEP :53: MHZ TRACKED PSW NONE CONTROLD 30-SEP :53: WILMA TRACKED PSW NONE CONTROLD 30-SEP :53: FTS TRACKED PSW NONE HORSEHEAD 28-JAN :37: FTS CALIBRATE PSW NONE HORSEHEAD 28-JAN :38: FTS TRACKED PSW NONE MRTCAL> read 1 Reading CONTROLD 30-SEP :52: MHZ CALIBRATE PSW NONE MRTCAL> read 1 /subscan 2 Reading CONTROLD 30-SEP :52: MHZ CALIBRATE PSW NONE

25 FITS reader: II. Dumping (1) MRTCAL> mdump --- Summary --- File name:./iram30m-4mhz s200-imb.fits controld Source name: Scan number: 200 Number of subscans: 3 Number of classes: 3 #1: calsky (1 subscan(s)) #2: calambient (1 subscan(s)) #3: calcold (1 subscan(s)) Subscans --- Number of subscans: 3 (3 found) #1: calibrate, calsky #2: calibrate, calambient #3: calibrate, calcold

26 FITS reader: II. Dumping (2) Primary HDU --- Header available --- IMBF-scan HDU --- Header available --- IMBF-frontend HDU --- Header available --- IMBF-backend HDU --- Header available --- IMBF-backend4MHZ HDU, subscan #2 --- Header available --- IMBF-antenna (slow) HDU, subscan #2 --- Header available --- IMBF-antenna (fast) HDU, subscan #2 --- Header available --- Data (subscan #1) --- Data available

27 MRTCAL> mdump backend --- Summary --- File name: FITS reader: II. Dumping (3)./iram30m-4mhz s200-imb.fits controld Source name: Scan number: 200 Number of subscans: 3 Number of classes: 3 #1: calsky (1 subscan(s)) #2: calambient (1 subscan(s)) #3: calcold (1 subscan(s)) --- IMBF-backend HDU --- XTENSION (C) = BINTABLE / binary table extension BITPIX (I4) = 8 / 8-bit bytes NAXIS (I4) = 2 / 2-dimensional binary table NAXIS1 (I4) = 81 / width of table in bytes NAXIS2 (I4) = 8 / number of rows in table EXTNAME (C) = IMBF-backend / name of this binary table extension SCANNUM (I4) = 200 / Scan number DATE-OBS (C) = T20:52:47.00 / observing date (Y2K format with time) in T PART (I4) = / Identification REFCHAN (I4) = / Refrence Channel CHANS (I4) = / Number of Channels DROPPED (I4) = / Channels dropped USED (I4) = / Channels used RECEIVER (C) = E E090 / Receiver connected BAND (C) = e0hli... e0vli / Sub-band specification POLAR (C) = NONE... NONE / Polarization PIXEL (I4) = / Pixel No. (arrays) REFFREQ (R4) = / [MHz] IF reference frequency SPACING (R4) = / [MHz] Spacing LINENAME (C) = NULL... NULL / Additional Line Name

28 FITS reader: II. Dumping (4) MRTCAL> mdump backend band --- Summary --- File name:./iram30m-4mhz s200-imb.fits Source name: controld Scan number: 200 Number of subscans: 3 Number of classes: 3 #1: calsky (1 subscan(s)) #2: calambient (1 subscan(s)) #3: calcold (1 subscan(s)) --- IMBF-backend HDU --- BAND is a character*16 column of dimensions 8 e0hli e0hli e0hli e0hli e0vli e0vli e0vli e0vli

29 FITS reader: II. Variables MRTCAL> variable MRTCAL> examine imbf%back% IMBF%BACK%! Structure GLOBAL IMBF%BACK%TABLE%LINENAME is a character* 16 Array of dimensions 8 IMBF%BACK%TABLE%SPACING is a real Array of dimensions 8 IMBF%BACK%TABLE%REFFREQ is a real Array of dimensions 8 IMBF%BACK%TABLE%POLAR is a character* 16 Array of dimensions 8 IMBF%BACK%TABLE%BAND is a character* 16 Array of dimensions 8 IMBF%BACK%TABLE%RECEIVER is a character* 16 Array of dimensions 8 IMBF%BACK%TABLE%PIXEL is an integer Array of dimensions 8 IMBF%BACK%TABLE%USED is an integer Array of dimensions 8 IMBF%BACK%TABLE%DROPPED is an integer Array of dimensions 8 IMBF%BACK%TABLE%CHANS is an integer Array of dimensions 8 IMBF%BACK%TABLE%REFCHAN is an integer Array of dimensions 8 IMBF%BACK%TABLE%PART is an integer Array of dimensions 8 IMBF%BACK%TABLE%STATUS = 0! Integer GLOBAL RO IMBF%BACK%TABLE! Structure GLOBAL IMBF%BACK%HEAD%NUSEFEED = 2! Integer GLOBAL RO IMBF%BACK%HEAD%FEBEFEED = 2! Integer GLOBAL RO IMBF%BACK%HEAD%FEBEBAND = 1! Integer GLOBAL RO IMBF%BACK%HEAD%DATE_OBS = T20:52:47.000! Character* 80 GLOBAL RO IMBF%BACK%HEAD%SCANNUM = 200! Integer GLOBAL RO IMBF%BACK%HEAD%DESC%EXTNAME = IMBF-backend! Character* 80 GLOBAL RO IMBF%BACK%HEAD%DESC%TFIELDS = 12! Integer GLOBAL RO IMBF%BACK%HEAD%DESC%GCOUNT = 1! Integer GLOBAL RO IMBF%BACK%HEAD%DESC%PCOUNT = 0! Integer GLOBAL RO IMBF%BACK%HEAD%DESC%NAXIS2 = 8! Integer GLOBAL RO IMBF%BACK%HEAD%DESC%NAXIS1 = 81! Integer GLOBAL RO IMBF%BACK%HEAD%DESC%BITPIX = 8! Integer GLOBAL RO IMBF%BACK%HEAD%DESC%XTENSION = BINTABLE! Character* 80 GLOBAL RO IMBF%BACK%HEAD%DESC! Structure GLOBAL IMBF%BACK%HEAD! Structure GLOBAL IMBF%BACK%STATUS = 0! Integer GLOBAL RO