A Proposed RHESSI Synoptic Data Archive

D. M. Zarro (SM&A/GSFC), R. C. Canfield (MSU), & A. Csillaghy (UCB)




CONTENTS


1. INTRODUCTION

2. SOHO Synoptic Database
2.1 Populating the Database
2.2 Searching the Database

3. RHESSI Flare/Synoptic Database
3.1 Creating the Database
3.2 Searching the Database


1. INTRODUCTION

In preparation for the NASA High Energy Solar Spectroscopic Imager RHESSI mission and in conjunction with the Max Millennium Program, the current capabilities of the SOHO Synoptic Database at the NASA/GSFC Solar Data Analysis Center (SDAC) will be enhanced to include additional context observations of solar flares observed with RHESSI. This Flare/Synoptic Database will provide two distinct functions:

  1. an online interface to synoptic datasets (e.g. daily images) for planning coordinated observations with RHESSI.
  2. a central, searchable archive of ground-based and space-based datasets for convenient joint analysis with RHESSI data.

Development and operation of the Flare/Synoptic database will draw heavily upon existing hardware, software, and network infrastructure at the SDAC. The Flare/Synoptic database will endeavor to include datasets (images, spectra, lightcurves, spectroheliograms) that were obtained at relevant times during RHESSI-observed events. The datasets will be obtained with the prior approval of each data source provider, and when possible, saved locally in standard formats (FITS). Typical present and future datasets that would be of great benefit to RHESSI analysis are identified below:







2. SOHO Synoptic Database

The SOHO Synoptic Database is an online-accessible database of space- and ground-based observations. These data are used for coordinated planning and analysis of SOHO observations. The SOHO Synoptic Database is accessible via a WWW interface that is updated daily with links to available images that have been copied (via FTP) from remote sites. An example of the main WWW interface is shown below.





Each link directs the user to all available synoptic images that have been copied for the corresponding day. A sample listing is shown below:







2.1 Populating the Database

The SOHO Synoptic Database is currently organized by date, with new images for each date added automatically by a UNIX cron service that periodically polls remote sites for new files. Files are transferred via a PERL script running on a server networked to the SOHO-ARCHIVE disk systems. The transferred files are generally (and preferably) in FITS format which are converted to GIF (and also JPEG) for subsequent online browsing. The transferred files are renamed according to the following naming convention: 



    bbso_halph_fd_19930820_1541.fts   <=== filename
    ---- ----- -- -------- ---- ---
      |    |    |     |      |   |
      |    |    |     |      |   |
      |    |    |     |      |  File extension (3 chars)
      |    |    |     |      |
      |    |    |     |   Observation time (4 chars, in hhmm format)
      |    |    |     |
      |    |    |  Observation date (8 chars, in yyyymmdd format)
      |    |    |
      |    |  Miscellaneous info code (2 chars)
      |    |
      |  Image type code (5 chars)
      |
    Observatory or instrument code (4 chars)

The file name consists of 31 characters in length 
(including 4 underscore characters and a dot).

The following is a list of typical observatory and instrument codes: 

    KBOU    Space Env. Lab, Boulder, Colorado
    KHMN    Holloman AFB, New Mexico
    HTPR    Haute-Provence
    LEAR    Learmonth
    MEUD    Meudon
    MITK    Mitaka
    NOBE    Nobeyama
    ONDR    Ondrejov
    KANZ    Kanzelhoehe Solar Observatory
    KSAC    Sacramento Peak, New Mexico
    BBSO    Big Bear Solar Observatory
    KPNO    Kitt Peak National Observatory
    MEES    Mees Solar Observatory
    MWNO    Mt. Wilson National Observatory
    YOHK    Yohkoh SXT
    SCDS    SOHO CDS
    SEIT    SOHO EIT
    SSUM    SOHO SUMER
    SUVC    SOHO UVCS
    SLAS    SOHO LASCO
    SMDI    SOHO MDI
    TRAC    TRACE
    OVRO    Owens Valley

The following is a list of typical image codes:

    BBAND   Broadband
    CAIIK   Calcium II K line
    CAXVM   Calcium XV synoptic coronal map
    DOPPL   Dopplergram
    HALPH   H alpha
    HEIMP   He I 10830, synoptic map
    MAGFE   Magnetogram, Fe 5250 A
    MAGMP   Magnetogram, synoptic map
    IGRAM   Intensitygram
    RADIO   Radio
    VMGAV   Vectomagnetogram, average
    VMGCI   Vectomagnetogram, component I
    VMGCQ   Vectomagnetogram, component Q
    VMGCU   Vectomagnetogram, component U
    VMGCV   Vectomagnetogram, component V
    VMGTF   Vectomagnetogram, transverse field
    WHITE   White light
    SOFTX   Soft X rays
    HARDX   Hard X rays
    00171   Fe IX/X line 171 A
    00195   Fe XII line 195 A
    00284   Fe XV line 284 A
    00304   He II line 304 A
    10830   He I line 10830 A

2.2 Searching the Database

The above naming convention facilities searching and retrieval of saved data files. Searching is performed via the WWW interface shown below:





The interface connects to the SOHO server and allows searching by image date, type (e.g. soft X-rays) and source (e.g. Yohkoh SXT). The search results can be returned as original FITS format files for subsequent analysis, or GIF/JPEG images for viewing.

3. RHESSI Flare/Synoptic Database

The RHESSI Flare/Synoptic Database will include datasets pertinent to RHESSI-observed events. In addition to synoptic images, these datasets will include concurrent high-time resolution images (such as provided by SXT and TRACE) of the flaring region, lightcurves (e.g. GOES and BATSE), spectra, and spectroheliograms at different wavelengths.

3.1 Creating the Database

To facilitate searching the database, an efficient metadata storage scheme is required. It is envisaged that a relational database system will provide an optimum solution. IDL software tools have already been developed for creating and querying a relational database. The following is a proposed schema for organizing the RHESSI Flare/Synoptic Database. 

          
#items
CAT_NUM         I*4     Catalog Number
FILENAME        C*80    Filename
EVENT_NUM       I*4     Event Number
DATE_OBS        R*8     Date/time of beginning of observation
DATE_END        R*8     Date/time of end of observation
XCEN            R*4     Observation center in solar X (arcsecs +W)
YCEN            R*4     Observation center in solar Y (arcsecs +N)
XSIZE           R*4     Width of field-of-view in  X (arcsecs)
YSIZE           R*4     Width of field-of-view in  Y (arcsecs)
ROLL            R*4     Roll relative to solar north (+ deg clockwise)
SOURCE          C*20    Data Source, e.g., SOHO, Yohkoh, ...
TYPE            I*2     0:Gamma-Ray, 1:HXR, 2:SXR, 3:EUV, 4:UV, 5:Optical 
CLASS           I*2     0:Image 1:Spectral 2:Lightcurve 3:Spectroheliogram
SUB_CLASS       C*10    e.g. EIT, SXT, TRACE, ...
DELETED         C*1     Deleted flag
DATE_MOD        R*8     Date and time when record was last modified


#index
EVENT_NUM       sort/index
CAT_NUM         sorted
DATE_OBS        sort
DATE_END        sort

#pointers
EVENT_NUM       hessi

Upon transfer from the remote site, each locally stored FITS file in the database is assigned a unique catalog number CAT_NUM. The filename is converted to the convention described in section 2.1. From the FITS header of each file, the data source site, observation time and coordinate pointing information are extracted. In addition, a data TYPE, CLASS, and SUB_CLASS are assigned. These parameters serve two important purposes. First they, permit rapid searching for subsets of data. Second, they provide a basis for defining object classes to aid subsequent data analysis.

The parameter TYPE is loosely related to wavelength and is designed to a provide the highest-level description of the dataset. Proposed values are:

0:Gamma-Ray, 1:Hard X-ray, 2:Soft X-ray, 3:EUV, 4:UV, 5:Optical, 6:Radio, 7: Magnetic

The parameter CLASS specifies the nature of the dataset. Proposed values are:

0:Image, 1:Spectrum, 2:Lightcurve, 3:Spectroheliogram

The parameter SUB_CLASS is a unique string name (e.g. SXT, EIT) that specifies the instrument (or detector) that produced the corresponding dataset.

The above proposed parameter definitions can be extended easily to include additional new data types. Finally, it is anticipated that each unique RHESSI event will be assigned a numeric event number that will act as pointer to a yet to be defined RHESSI catalog. Inclusion of this event number as an item EVENT_NUM in the Flare/Synoptic database will enable rapid and efficient cross-referencing and searching for overlapping (temporal and spatial) RHESSI and synoptic datasets.

3.2 Searching the Database

A test RHESSI Flare event catalog and associated relational database of Flare/Synoptic data has been created. The panel below shows a prototype IDL/widgets interface that demonstrates coordinated searching of RHESSI events and associated synoptic observations. Searching is currently based only on date/time ranges. The test synoptic database currently only includes selected Yohkoh SXT and SOHO EIT imaging observations. Selection of a RHESSI event number returns a list of flare/synoptic datasets for the current day that are locally stored. Selection of one of these datasets returns a display of the corresponding data. Planned enhancements of this interface include:





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