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Multi-Application Solar Telescope Preliminary results Shibu K. Mathew Udaipur Solar Observatory

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  • Multi-Application Solar Telescope Preliminary results

    Shibu K. Mathew Udaipur Solar Observatory

  • Multi-Application Solar Telescope

    – Past Telescope specs. and components

    Installation

    Optical alignment and tests

    – Present Back-end instruments

    Preliminary observations

    – Future Adaptive optics implementation

    Regular G-Band and H-alpha observations

    Vector magnetic field imaging

  • Multi-Application Solar Telescope Telescope specs. and components

    Salient features

    50 cm off - axis design for reduced scattered light.

    Zerodur primary, secondary and Coude mirrors with SiC.

    /12 wave front error, around 0.25 arc-sec resolution at 600 nm.

    Alt-azimuth mount, image de-rotator for FOV rotation compensation.

    Active thermal control on M1 and all the other mirrors, maintained within ± 1o C to the ambient.

    Collapsible dome, no trapped heat and thus no dome seeing.

    Hexapod mounted secondary mirror for active compensation of aberrations due to thermal flexure.

    Back-end instruments on a stable platform beneath

    the telescope floor

  • Multi-Application Solar Telescope Telescope specs. and components

    Collimated beam

    Optical Design

    Primary mirror (M1) : Off-axis parabola, 2m focal length, surface figure (rms) /30, Zerodur.

    Secondary mirror (M2) : Off-axis parabola, 200 mm focal length, SiC , surface figure (rms) /40.

    Coudé Train (M3 - M5) : Plane mirrors, SiC, , surface figure (rms) /60.

    De-rotator Mirrors (DM1 – DM3) : Plane mirrors, Zerodur, , surface figure (rms) /60.

    Folding Mirror (M6) : Plane mirror, Zerodur, provides

    light to the back-end instruments, , surface figure (rms) /60

    M1

    M2

    M3 M4

    M5

    DM1 DM2

    DM3

    M6

    Output wave-front error better than /12

  • Multi-Application Solar Telescope Telescope specs. and components

    Mechanical design

    A stiff central structure connecting the two altitude shafts

    A reinforced strut structure to connect the central structure and M2

    M2 is mounted on a hexapod with correction capabilities for tilt, decentring, and translation

    Support structure for the polarimeter package in the strut

    Specifications

    Differential pointing accuracy : 0.5 arc-sec

    Open loop tracking : 0.25 arc-sec for 10 min

    Closed loop tracking : 0.1 arc-sec for 1 Hr

    M2 mechanism : tip-tilt system

  • Multi-Application Solar Telescope Telescope specs. and components

    Thermal design

    The tubes and the fork, are shaded from the sun’s illumination by an upper sunshield system.

    The M1 mirror is thermally controlled by means of airflows with controlled temperature

    The primary mirror surface is kept at within 1oC ambient

    Telescope Control System (TCS) Telescope Control System (TCS) software is written in LabView. PLC control for the thermal and pneumatic systems. UMAC controllers for the azimuth, elevation and de-rotator drives. The TCS can be accessed and the telescope can be controlled remotely over Ethernet.

  • Multi-Application Solar Telescope Telescope Installation

    The entire telescope mechanical structure transported

    from AMOS in three pieces, the largest weighing more than 4 tonnes.

    The boxes were transported to the island (around 700m from the shore) on a large pontoon.

    Steel structure was erected for lifting the boxes from

    the lake to the building top.

  • Multi-Application Solar Telescope Optical alignment and tests

    Both theodolite and Zygo interferometer are used for the optical alignment.

    Preliminary alignment of all the mirrors with respect to the telescope and optic axes using theodolite.

    A 60 cm flat mounted in front of the telescope and a Zygo interferometer are used for measuring wave-front errors.

    Secondary hexapod parameters were adjusted to minimize the errors in optical alignment of M1 & M2

  • Multi-Application Solar Telescope Optical alignment and tests

    Tracking Tests

    Tests carried out using G-band observations.

    Sunspots tracked in 10 Hrs of data, in HG co-ordinate frame.

    Shift of the sunspot calculated by registering the mages.

    Maximum shift is with in 15 arc-sec for 10 Hrs, 0.025 arc-sec/min

  • Multi-Application Solar Telescope Telescope & Observing floor

    Telescope floor Telescope enclosed with in the collapsible dome

    Back-end instruments on the observing floor

  • Multi-Application Solar Telescope Back-end instruments

    Broad G-band and Narrow-band H-alpha imager

    CCD G-band

    Halle Filter L1

    BS

    CC

    D H

    -alp

    ha

    G-band IF

  • Multi-Application Solar Telescope Back-end instruments

    Broad G-band imager

    Broad band interference filter

    1nm passband

    1376 x 1040 PCO Sensicam CCD

    3 arc-min field-of-view

    Better than 10 images/sec temporal resolution

    Available for regular observations

    Narrow band H-alpha imager

    Narrow band Birefringent Halle filter

    500 mÅ band-pass 1024x1024 Photon Max CCD to cover 3arc-min

    Tuning capability, will be used for making

    Dopplergrams Better than 5 images/sec temporal resolution Available to make regular line-center

    observations

  • Multi-Application Solar Telescope G-band and H-alpha sample images

    G-band, AR 12192, 22 October 2014

  • Multi-Application Solar Telescope G-band and H-alpha sample images

    H-alpha, AR 12192, 22 October 2014

  • Multi-Application Solar Telescope G-band and H-alpha sample images

    H full disk image constructed from a sequential mosaic of 293 images taken by MAST on 19th May 2015.

  • Multi-Application Solar Telescope G-band and H-alpha sample images

    G-band & H-alpha

  • Multi-Application Solar Telescope G-band and H-alpha sample images

    G-band & H-alpha

  • Multi-Application Solar Telescope G-band and H-alpha sample images

    AR 12436, 24 Oct 2015

  • Multi-Application Solar Telescope Back-end instruments

    Fabry-Perot Narrow band imager for Magnetic field measurements

    • Two voltage tunable lithium niobate FP etalons in tandem, resulting pass-band around 60 mÅ @ 617.3 nm

    • Filter wheel with two or more pre-filters.

    • Presently two wavelengths at 617.3 nm and 854.2 nm (FeI and CaII) for photospheric and chromospheric observations.

    • The filters were tested using a Littrow spectrograph installed close to the imager

  • Multi-Application Solar Telescope Back-end instruments

    Fabry-Perot Narrow band imager : voltage tuning Littrow Spectrograph

    FP1

    FP

    2

    M1

    M2

    M

    3

    M4

    M

    5

    Fro

    m M

    AST

    FP2 -3000V

    FP2 +3000V

    FP1 +3000V

    FP1 -3000V

  • Multi-Application Solar Telescope Back-end instruments

    Fabry-Perot Narrow band imager

    61

    7.3

    nm

    Pre

    -Filter

    FP1

    +FP2

    +Prefilte

    r

  • Multi-Application Solar Telescope Back-end instruments

    Fabry-Perot Narrow band imager; optical layout

    From MAST

    FP1 FP2

    CC

    D

    Pre-filter

    AO Components

    Polarimeter

  • Multi-Application Solar Telescope Back-end instruments

    Fabry-P

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    g re

    sult:

    22

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    61

    7.3

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  • Multi-Application Solar Telescope Back-end instruments

    Polarimeter

    (in degree)

    Fast axis of

    LC1, =0

    (in degree)

    Fast axis of

    LC2, =45

    Measured

    Intensity, Imeas

    315.0 305.264 I1=I+Q/3+U/3+V/3

    315.0 54.736 I2=I+Q/3-U/3-V/3

    225.0 125.264 I3=I-Q/3-U/3+V/3

    225.0 234.736 I4=I-Q/3+U/3-V/3

    (in

    degree)

    (in

    degree)

    Imeas

    360 90 I1=I-V

    360 270 I2=I+V

    Modulation Scheme

    2 LCVRs and Linear polarizer

  • Multi-Application Solar Telescope Back-end instruments

    Polarimeter, initial results from I+V & I-V measurement

    I+V I-V V/I o-65mÅ

    ~o

  • Multi-Application Solar Telescope Back-end instruments

    Polarimeter, initial results from I+V & I-V measurement

  • Multi-Application Solar Telescope Back-end instruments

    Adaptive optics Deformable membrane mirror for the wave-front correction (MMDM), Schack Hartmann (SH)

    wavefront sensor.

    Tip-tilt mirror for the correction of image wobbling if any

    No. of actuators : 19, No. lenslets in SH: 19, Being integrated and tested with MAST

    Initial

    test

    resu

    lts fro

    m

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    . 1

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  • Multi-Application Solar Telescope Conclusion & Future plans

    • MAST Installation completed.

    • Telescope tested for wave-front accuracy and tracking errors.

    • Presently, regular observations can be obtained in G-band and H-alpha.

    • Integration of the back-end instruments are in progress.

    • Narrow-band imager along with polarimeter are being used for test observations.

    • Adaptive optics in the beginning of 2016.

  • Multi-Application Solar Telescope Data products & SUIT connection

    • High cadence G-band and H-alpha images • Active region evolution in Photosphere and Chromosphere • Flare and prominence studies • H-alpha Dopplergrams providing los velocities

    • Photospheric vector magnetic field using FeI 617.3 nm line

    • Full line profile and all the Stokes profiles (I, Q, U, V) • Ca II 854.2nm line centre images for Chromospheric studies • Chromospheric magnetograms in CaII 854.2 nm with limited line profile scans All of the above data products could be used for understanding the relation between the magnetic field and the features observed in different SUIT wavelengths ------------------------------------- Thank you ---------------------------------------------