August 30 Wed 13:30-15:00 Solar and Space Plasma Seminar
hybrid; Central Building (North)310 or Zoom
August 30 Wed 14:30-15:30 ALMA-J seminar
Zoom / ALMA building #102 (hybrid)
詳細は下記からご覧ください。
=============== August 30 Wed===============
Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：Aug 30th (Wed), 13:30-15:00
Place： hybrid; Central Building (North) / 310 or Zoom
Speaker：Dr. Masahito Kubo
Affiliation：NAOJ
Title：Comparison of polar magnetic fields derived from MILOS and MERLIN inversions for Hinode/SOT-SP data
Abstract：The detailed investigation of the polar magnetic field and its time evolution is one of the major achievements of Hinode. Precise measurements of the polar magnetic field are essential for understanding the solar cycle, and they provide important constraints for identifying the source regions of the solar wind. The Spectropolarimeter (SP) of the Solar Optical Telescope (SOT) on board Hinode has been the instrument best suited to make such measurements. In this study, we compare SOT-SP data for the polar regions as processed using two representative Milne-Eddington inversion codes, MILOS and MERLIN. These codes are applied to the same level-1 SOT/SP data, and the same disambiguation algorithm is used on the maps that go through the two inversions. We find that the MERLIN inversion tends to give the radial magnetic flux density (the magnetic flux density with respect to the local vertical) that is about 20% larger than the MILOS inversion. The somewhat higher radial magnetic flux density from MERLIN appears to be common to the polar magnetic fields observed at different phases of the solar cycle. We attribute the difference in the radial magnetic flux density to different filling factors adopted by the two inversions, based on different assumptions of the scattered light profiles. The relationship between the radial magnetic flux density and the magnetic filling factor could be more complex in the polar (limb) observations due to the possible contributions of the transverse magnetic field component that may affect the estimated radial magnetic flux density.
Facilitator
-Name：Takayoshi oba
-Comment：in English
=============== August 30 Wed==============
Campus: Mitaka
Seminar: ALMA-J seminar
Regularly Scheduled/Sporadic: Every Wednesday
Date and time: August 30, 2023 (Wed), 14:30-15:30
Place: ALMA building #102 / Zoom (hybrid)
Speaker: Jan-Willem Steeb
Affiliation: National Radio Astronomy Observatory
Title: AstroHACK: Holography Antenna Commissioning Kit
Abstract: Correcting the surface of a dish antenna by adjusting the panels can significantly improve the dish’s performance. For instance, the VLA panel adjustments completed in 2000 more than doubled the high-frequency sensitivity of the VLA dishes. The software presently utilized by ALMA and VLA is written in Fortran and is becoming challenging to maintain. Consequently, the CASA team is developing AstroHACK, which generates antenna aperture images and calculates antenna panel adjustment corrections from calibrated holography measurement sets. AstroHACK is the first non-prototype software package developed using the Python-based VIPER (Visibility and Image Parallel Execution Reduction) Framework, previously known as the CASA Next Generation Infrastructure Software Framework. This framework was designed to meet the requirements of the ngVLA and the ALMA Wideband Sensitivity upgrade. In this seminar, I will provide an overview of the VIPER Framework and the functionalities of AstroHACK, followed by a live demonstration.