Abstract Details
| Name: Mohana Krishna.R Affiliation: IISc - ISRO Conference ID: ASI2016_864 Title : Multi Slit Spectro-polarimeter – a high cadence solar spectro-polarimeter Authors and Co-Authors : Dr.Sankarsubramanian.K ISRO Raja Bayanna - USO Dr.Shibu Mathew - USO Dr. Ashok - ISRO Sowmya.H.K - ISRO Kumar - ISRO Abstract Type : Poster Abstract Category : Instrumentation and Techniques Abstract : A Multi-slit Spectro-polarimeter (MSSP) has been developed at the Space Astronomy Group of ISRO Satellite Centre for high cadence magnetic field observation of solar atmosphere. MSSP is designed to perform spectroscopy and polarimetric studies for simultaneous observation of the photosphere and chromosphere using Fe I 630.2nm and HeI 1083 nm respectively. With five slits scanning the FOV simultaneously, the achieved time cadence would be five time better than a single slit configuration. The instrument consists of a blazed grating with the blaze angle optimized for Fe I and He I lines. As the grating works at high orders and the usage of multi-slit, a DWDM type filter is used as the filter rather than the conventional order separation filters. DWDM filters have a flat-top response with a FWHM bandwidth of 6 angstrom. This filter is very sensitive to tilt and f-ratio of the input beam. An f-20 or slower beam gives satisfactory response. Laboratory tests were done on scanning mechanisms which is used to scan the image across the slit and found that a complete FOV can be covered in 2min. However, this would be dependent on the exposure time and the required signal-to-noise ratio. Spectrograph’s spectral resolution is expected to be better than 30 milli-angstrom and from experiments it is found to be 26 milli-angstrom. Spectral dispersion of the system was found to be 10 milli-angstrom per pixel. This instrument is being placed as a back end instrument for the Multi Aperture Solar Telescope (MAST) at Udaipur Solar Observatory (USO). MAST is a 50cm off axis telescope installed at USO and was commissioned in the month of September 2015. The current engineering run is to achieve spectroscopy in 630.2nm line which will then be extended to polarimetry mode in future runs. This run is aimed at achieving the proposed spatial and temporal resolution. Preliminary results related to the engineering run will be discussed and the parameters like spatial, spectral resolution will be estimated from this run. The spectroscopic performance of this instrument in the actual field station will be discussed in this paper. |