Results of the magnetometer inter-comparisons during the 2nd Cycle of Geomagnetic Information Renewal in the Republic of Croatia

Between 2017 and 2021, the 2nd Geomagnetic Information Renewal Cycle was carried out on the Croatian Geomagnetic Repeat Stations Network (CGRSN). On several occasions, before and after the survey at CGRSN, the magnetometers used in the survey were tested at the Lonjsko Polje Geomagnetic Observatory (LON). This paper presents the methods and results of these tests. The results verified the correctness of the used magnetometers and confirmed that their absolute accuracy is within the targeted measurement accuracy at the secular point. Despite the favourable results, a detail analysis revealed the presence of a small magnetic offset. This offset was introduced during the comparison process and did not affect the CGRSN measurements results in any way. In this paper, we share our experience which could be instructive for other observers performing similar work. Further testing is needed to determine the exact direction and magnitude of this systematic offset. Između 2017. i 2021. izvršen je II. ciklus obnove geomagnetske informacije u Hrvatskoj Mreži Geomagnetskih Sekularnih Točaka (HMGST). U nekoliko navrata, prije i nakon izmjere na HGMST, obavljeno je ispitivanje magnetometara korištenih u izmjeri u Geomagnetskom opservatoriju Lonjsko polje (LON). U ovom radu predstavljene su metode i rezultati ovih ispitivanja. Rezultati su verificirali ispravnost korištenih magnetometara i potvrdili da je njihova apsolutna točnost unutar ciljane točnosti izmjere na sekularnoj točci. Bez obzira na povoljne rezultate, detaljna analiza otkrila je prisutnost malog magnetskog odstupanja. Ovo odstupanje javilo se prilikom postupka usporedbe i ni na koji način nije utjecao na rezultate mjerenja na HMGST. U ovom radu dijelili smo naše iskustvo koje bi moglo biti poučno za druge motritelje koji rade sličan posao. Potrebno je provesti dodatna ispitivanja kako bismo odredili točan smjer i iznos ovog sistematskog odstupanja.