2.1. Description

An INTERMAGNET Magnetic Observatory (IMO) is a magnetic observatory with full absolute control, making continual data recordings at a minimum rate of one minute. One minute magnetic field values should be measured using a vector magnetometer and, optionally, a scalar magnetometer. Vector measurements performed by a continually recording magnetometer are typically variation measurements and variation data, transmitted as reported data, can be accepted by INTERMAGNET GINs from existing member observatories. However, it has been considered best practice since Technical Manual V4.0 (1999) that variometer data are corrected to near absolute values using the best available baseline estimates at the time of transmission. Observatories making new applications for INTERMAGNET membership will be required to transmit data with best available baseline estimates applied.

IMOs are required to transmit preliminary data in an INTERMAGNET recognized format (see Section 6.1.1) to one of the INTERMAGNET Geomagnetic Information Nodes (GIN) by electronic means within 72 hours of recording. Data are typically transmitted over the Internet or through satellite such that preliminary data can be made available on the INTERMAGNET web site. Note that, for the time being, GINs also accept reported data from observatories that have historically transmitted such data.

Within 3-months, observatories may transmit quasi-definitive data to one of the INTERMAGNET GINs provided these data meet the provisional baseline conditions outlined in APPENDIX A . Quasi-definitive data submission is by the same method as preliminary data submission (described in Section 6.2). Observatories may submit quasi-definitive data in place of preliminary data if this meets the requirement of being received within 72 hours of recording, but ideally faster (see Section 6.1.4).

At the end of a calendar year, data are to be prepared using final baselines and submitted as definitive data for inclusion in the INTERMAGNET Reference Data Set (IRDS). The deadline for submission will be communicated by INTERMAGNET.

An observatory intending to participate in INTERMAGNET as an IMO must be able to meet the INTERMAGNET standards for one-minute data detailed below and agree to the conditions for data transmission detailed in the INTERMAGNET Participation Policy. The Participation Policy is included in Chapter 8 along with instruction for observatories wishing to make an IMO application. Further information is also available from the INTERMAGNET Observatories Subcommittee chair.