The fly's eye project: Sidereal tracking on a hexapod mount

The driving objective of the Fly's Eye Project is a high resolution, high coverage time-domain survey in multiple optical passbands: our goal is to cover the entire visible sky above the 30° horizontal altitude with a cadence of ~ 3 min. Imaging is intended to perform with 19 wide-field cameras mounted on a hexapod platform. The essence of the hexapod allows us to build an instrument that does not require any kind of precise alignment and, in addition, the similar mechanics can be involved independently of the geographical location of the device. Here we summarize our early results with a single camera, focusing on the sidereal tracking as it is performed with the hexapod built by our group

Exploring the transient sky with the Fly's Eye Camera System

To study astrophysical transit phenomena we follow an alternative strategy for getting high-cadence observations of the field. This can be achieved with our new Fly’s Eye Camera System that monitors the entire sky above 30◦horizontal altitude. With this instrument one can observe all phenomena brighter than∼15min Sloan r-band (u’, g’,i’ and z’ filters are also available). If we stack together a few hour of images we can observe∼17mfaint sources. This small-sized instrument is designed for time-domain astronomy with its150 sec cadence. Due to the hexapod-based motion control, the instrument can be installed anywhere without any modifications, it can accomplish sky tracking automatically. These parallel robots have 6 degrees of freedom (DoF), but since any kind of rotation can be done by using only 3 DoF, the tracking with hexapods is independent from the geographical coordinates. Even polar alignment is not required, because Fly’s Eye can calibrate itself based on its own observed data. The system is optimal for time-domain astronomy: detecting novae, supernovae, optical afterglows of gamma-ray bursts and other bright, fast transients, and, from the observation database such data can be obtained - even from before the discovery of the transient event. In the future when the direction of the gravitational waves will be defined precisely we will be able to detect their first multiwaveband counterparts. In addition the Fly’s Eye will support the “Transient Astrophysical Objects”project which will use two new 80 cm robotic telescopes for follow-up observations of transients

Expected accuracy of tilt measurements on a novel hexapod-based Digital zenith camera system: A Monte-Carlo simulation study

Digital zenith camera systems (DZCS) are dedicated astronomical-geodetic measurement systems for the observation of the direction of the plumb line. A DZCS key component is a pair of tilt meters for the determination of the instrumental tilt with respect to the plumb line. Highest accuracy (i.e., 0.1 arc-seconds or better) is achieved in practice through observation with precision tilt meters in opposite faces (180° instrumental rotation), and application of rigorous tilt reduction models. A novel concept proposes the development of a hexapod (Stewart platform)-based DZCS. However, hexapod-based total rotations are limited to about 30°–60° in azimuth (equivalent to ±15° to ±30° yaw rotation), which raises the question of the impact of the rotation angle between the two faces on the accuracy of the tilt measurement. The goal of the present study is the investigation of the expected accuracy of tilt measurements to be carried out on future hexapod-based DZCS, with special focus placed on the role of the limited rotation angle. A Monte-Carlo simulation study is carried out in order to derive accuracy estimates for the tilt determination as a function of several input parameters, and the results are validated against analytical error propagation.As the main result of the study, limitation of the instrumental rotation to 60° (30°) deteriorates the tilt accuracy by a factor of about 2 (4) compared to a 180° rotation between the faces. Nonetheless, a tilt accuracy at the 0.1 arc-second level is expected when the rotation is at least 45°, and 0.05 arc-second (about 0.25 microradian) accurate tilt meters are deployed. As such, a hexapod-based DZCS can be expected to allow sufficiently accurate determination of the instrumental tilt. This provides supporting evidence for the feasibility of such a novel instrumentation. The outcomes of our study are not only relevant to the field of DZCS, but also to all other types of instruments where the instrumental tilt must be corrected. Examples include electronic theodolites or total stations, gravity meters, and other hexapod-based telescopes

The validation of the Hungarian version of the ID-migraine questionnaire

Despite its high prevalence, migraine remains underdiagnosed and undertreated. ID-Migraine is a short, self-administrated questionnaire, originally developed in English by Lipton et al. and later validated in several languages. Our goal was to validate the Hungarian version of the ID-Migraine Questionnaire.Patients visiting two headache specialty services were enrolled. Diagnoses were made by headache specialists according to the ICHD-3beta diagnostic criteria. There were 309 clinically diagnosed migraineurs among the 380 patients. Among the 309 migraineurs, 190 patients had only migraine, and 119 patients had other headache beside migraine, namely: 111 patients had tension type headache, 3 patients had cluster headache, 4 patients had medication overuse headache and one patient had headache associated with sexual activity also. Among the 380 patients, 257 had only a single type headache whereas 123 patients had multiple types of headache. Test-retest reliability of the ID-Migraine Questionnaire was studied in 40 patients.The validity features of the Hungarian version of the ID-Migraine questionnaire were the following: sensitivity 0.95 (95% CI, 0.92-0.97), specificity 0.42 (95% CI, 0.31-0.55), positive predictive value 0.88 (95% CI, 0.84-0.91), negative predictive value 0.65 (95% CI, 0.5-0.78), missclassification error 0.15 (95% CI, 0.12-0.19). The kappa coefficient of the questionnaire was 0.77.The Hungarian version of the ID-Migraine Questionnaire had adequate sensitivity, positive predictive value and misclassification error, but a low specificity and somewhat low negative predictive value

Serum concentrations of 25-OH vitamin D in patients with systemic lupus erythematosus (SLE) are inversely related to disease activity: is it time to routinely supplement patients with SLE with vitamin D?

Background Low serum vitamin D concentrations havebeen reported in several autoimmune disorders.Objective To assess whether low serum vitamin Dconcentrations are related to disease activity of patientswith systemic lupus erythematosus (SLE).Methods 378 patients from several European andIsraeli cohorts were pooled and their disease activitywas measured by two different methods: 278 patientshad SLE disease activity-2000 (SLEDAI-2K) scores and100 patients had European Consensus Lupus ActivityMeasurement (ECLAM) scores. In order to combinethe two systems the scores were converted intostandardised values (z-scores), enabling univariatesummary statistics for the two variables (SLEDAI-2Kand ECLAM). The commercial kit, LIAISON 25-OHvitamin D assay (310900-Diasorin) was used tomeasure serum concentration of 25-OH vitamin D in378 patients with SLE.Results A signifi cant negative correlation wasdemonstrated between the serum concentration ofvitamin D and the standardised values (z-scores) ofdisease activity scores as measured by the SLEDAI-2Kand ECLAM scales (Pearson's correlation coeffi cientr=?0.12, p=0.018).Conclusions In a cohort of patients with SLEoriginating from Israel and Europe vitamin D serumconcentrations were found to be inversely related todisease activit

Serum concentrations of 25-OH vitamin D in patients with systemic lupus erythematosus (SLE) are inversely related to disease activity: is it time to routinely supplement patients with SLE with vitamin D?

Background Low serum vitamin D concentrations havebeen reported in several autoimmune disorders.Objective To assess whether low serum vitamin Dconcentrations are related to disease activity of patientswith systemic lupus erythematosus (SLE).Methods 378 patients from several European andIsraeli cohorts were pooled and their disease activitywas measured by two different methods: 278 patientshad SLE disease activity-2000 (SLEDAI-2K) scores and100 patients had European Consensus Lupus ActivityMeasurement (ECLAM) scores. In order to combinethe two systems the scores were converted intostandardised values (z-scores), enabling univariatesummary statistics for the two variables (SLEDAI-2Kand ECLAM). The commercial kit, LIAISON 25-OHvitamin D assay (310900-Diasorin) was used tomeasure serum concentration of 25-OH vitamin D in378 patients with SLE.Results A signifi cant negative correlation wasdemonstrated between the serum concentration ofvitamin D and the standardised values (z-scores) ofdisease activity scores as measured by the SLEDAI-2Kand ECLAM scales (Pearson's correlation coeffi cientr=?0.12, p=0.018).Conclusions In a cohort of patients with SLEoriginating from Israel and Europe vitamin D serumconcentrations were found to be inversely related todisease activit