Table 3.6: Data availability
Table 3.6 indicates where and when the various data sets are to be available. The exchange of data between SOHO experimenters will facilitate the successful implementation of joint observing programs to achieve common science objectives. Electronic access to data sets remote to an individual PIs computer system provides a quick and reliable mechanism for the collaborative exchange of data. The following plan for data availability requires a submission of data from the PI teams as soon as possible after receipt, and hopefully within 24 hours. Therefore most of the inputs to the summary data should be generated by automated procedures. For example, the planned observing schedule should be generated from the planned command load.
In Table 3.6, an X indicates data availability at that facility. If a time is indicated, then the data set will be available within the time specified. The MDI High Data Rate Data will be delivered directly to Stanford University and will not go through the EOF. However the MDI magnetogram data occurring at the end of every tape recorder playback will be delivered to the EOF.
The spacecraft housekeeping shall be archived for electronic access from the EOF for 28 days after data collection. The data may be kept as digital counts, but conversion to engineering units would be preferable.
The maintenance of quick look science data is the responsibility of the PI teams. While it is desirable that the most recent 30 days be kept on-line or near on-line, it is recognized that each experiment team will have different requirements and different capabilities and no fixed requirement for on-line data retention can be imposed on the PI teams.
The DDF will mail a hard copy (currently, in CD-ROM) of the respective level--0 science/housekeeping and ancilliary data to each PI within 30 days of receipt at GSFC. The PI is then responsible for further distribution to Co-Is and support institutions. In addition, such telemetry data will be available in the form of "snapshots" for limited call up to approved participating organisations. Those data, available electronically from the Central Data Handling Facility (CDHF), will represent the most recent 8 days of information.
Each PI will receive a copy of his own investigation data set, and of any other if so agreed, after 30 days of reception by DDF.
CDHF will process the key parameters for CELIAS and CEPAC to be included in the Summary Data. The Summary Data and the As-Run Plan, created and maintained on line at the EOF, is sent to CDHF for hard copy (CD-ROM) distribution. Both CDHF and EOF will keep these data online.
A number of SOHO participating institutes (PIs and others) will hold archives of the Science and processed science data corresponding to the experiment of their responsibility.
The central archiving facility for processed data is being developed at the EOF. This archive will hold the complete set of SOHO data with the only exception of the high data rate MDI helioseimology data set.
The following data sets will be generated for SOHO and available from the EOF archive:
The various database catalogs may be accessed electronically over the EOF LAN. The catalogs will be data base tables that are linked together using standard relational data base techniques. A standard query language (SQL) is used to access the databases, but an interface program has been developed in order to use more user-friendly front ends to the EOF archive. The first interface is World-Wide-Web based and its available to anyone with Internet access. The second one is based on IDL and will be used mainly within the EOF for data analysis purposes.
The type of information stored into these database files will fall into several categories. The first category will consist of information about observing programs. For this category, a standard set of data field names and their definition has been prepared to provide uniformity in developing the individual experiment databases. Not all fields names may apply to a particular instrument, in which case that field will simply be blank for that instrument. The type of information stored in these databases will include information like identification of what type of observing program was followed, the purpose or target of the observing program, the time range of the observing program, and the heliographic area of the sun covered. Users will be able to simultaneously sample this information not only at the EOF, but worldwide. This will be accomplished maintaining a combined database incorporating this information from all the instruments on a central file server system using updates supplied by the PI teams. There will be two main datasets: the As Plan File, describing the upcoming observing plans of the instruments (will reside at ECS), and the As Run File detailing what was actually observed. This last file will be part of the Summary Data set.
The second category of database files will contain information about events that may be relevant to more than one instrument. Exactly what information will be stored in this catalog is yet TBD, but most likely it will contain the same information as found in the Observatory Log (section 3.1.4). This could consist of information about such things as spacecraft rolls, as well as information about solar events and features. Information for this file will be received from several sources: CMS (spacecraft events), ECS (global planning related events) and PI workstations. This database will also contain information about events registered by other observatories, that may be relevant to the SOHO observations. Related into this events catalog will be additional database files which will serve to logically relate the events to the individual SOHO observations, and to store information about what effect a given event had on a given observation, if any.
The third category of database will contain information about scientific data. Several tables will describe science processed, summary and synoptic observations. Access to this data sets will be unrestricted unless otherwise specified in the SOHO Science Working Team data rights agreements. Ancillary, summary, event and synoptic data will be in the public domain immediately after acquisition. The science processed data will be public after an initial period of restricted access.
There will be a way for users to attach comments to the individual entries in each of the database files. The procedure used to control this process is as yet TBD.