Abstract Details
| Name: Shanti Prabha Affiliation: IIA, Bengaluru Conference ID: ASI2019_265 Title : Spectroscopic Imaging of Nebular Gas: Cubesat based spectrometer to explore nebular astrophysics through imaging spectroscopy Authors and Co-Authors : Shanti Prabha, B.G. Nair, Ambily Suresh, Margarita Safanova, Jayant Murthy Abstract Type : Poster Abstract Category : Instrumentation and Techniques Abstract : One of the most exciting parts of the astrophysical spectrum is the far-ultraviolet (FUV: 912 – 1800 Å). Indian Institute of Astrophysics (IIA) is planning to develop an imaging spectrometer to observe and study diffuse nebulae. The spectrometer will be incorporated into a 6U size (300 x 200x 100 mm) satellite. The FUV spectrometer will be designed for operation in the spectral range of 900 and 1800 A0. The field of view is 4° x 1’ with a spatial resolution of 13″ and a spectral resolution of 0.6 Å (Resolution ~2000). The spectrometer employs an off-axis parabolic (OAP) mirror with SiC coating, to maximise the collecting area we have selected a rectangular aperture for the mirror. Incident light focussed by the OAP will be allowed through the slit onto a grating, which is mounted in a Rowland circle configuration. The grating is a toroid (40 mm x 40 mm) with 1800 lines per mm to obtain the necessary resolution, the toroid disperses and focus the light on to a 2k×2k detector plane. We have chosen a toroidal grating because it is possible to achieve low astigmatism over a range of wavelengths with the toroid geometry. The detector will be a GaN coated MCP based detector developed by the Institute of Astronomy and Astrophysics at the University of Tübingen. Material selection of components for the spectrograph, geometry of the OAP, coating, type and size of the detector and the parameters of the grating will be discussed in detail. To determine the positions of the components, ray tracing(sequential) is done. Aberrations in the grating can be found by path length calculations which we have used for minimize the effect introduced by astigmatism etc. In this work we present the optical design of the spectrometer using hand calculations and computational simulations using Zemax software. |