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TSST H-alpha Full Disk Images
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.. contents:: Table of contents

The Hα channel of the TSST is a Daystar SR-127 QT, an achromatic refractor with 127 mm aperture and a focal length of 2667 mm. The telescope features a narrow band filter with a passband of 0.04 nm centered at the Hα line. The filter is a temperature stabilized etalon in collimated configuration, and it is the same filter used in the GONG network for the Hα channel to monitor the chromospheric transients (Giersch, 2013). The Hα channel is equipped with a focal reducer, acting also as a field curvature corrector, to match the Dalsa Pantera 1M60 pixel scale of the MOF channel (2.6 arcsec/pixel). The main goal of this TSST channel is the real time detection of flaring region (Piazzesi et al., 2012, Pötzi et al., 2015, 2018) during the impulsive and flash phases when the intensity reaches its maximum (Benz, 2017). Hα images are extremely important for ground based SWe monitoring (see, e.g. Veronig & Potzi, 2016) and to automatically detect and track structures in the solar chromosphere, as filaments (Bernasconi et al., 2005, Fuller et al., 2005, Bonnin et al., 2013) and prominences (Wang et al., 2010), that can be associated with flare and coronal mass ejections.

References
~~~~~~~~~~



Dataset summary
~~~~~~~~~~~~~~~

.. list-table::

  * - **internal_name:**
    - unitov_halpha_tsst_image
  * - **publisher:**
    - University of Rome Tor Vergata
  * - **alph_code:**
    - 2
  * - **id_tmp:**
    - 59
  * - **short_name:**
    - TSST-halpha
  * - **identifier:**
    - aspis:///unitov/halpha_tsst_image
  * - **dynamic:**
    - data collection grows in time. Bulk size estimated on 1 yr. Cadence: at least one image per day in clear weather conditions (up to 5/8 per day) one image every 5 s for some minutes (<60 minutes) during flares
  * - **size:**
    - 20GB
  * - **format:**
    - .fits
  * - **type:**
    - image
  * - **records_number:**
    - 9
  * - **time_start:**
    - 2022-09-01
  * - **time_stop:**
    - 2023-05-01
  * - **spatial:**
    - SUN
  * - **messenger:**
    - photons
  * - **spectral_min:**
    - 656.26
  * - **spectral_max:**
    - 656.34
  * - **spectral_units:**
    - nm
  * - **observable:**
    - spect.line.intensity,AR,flare
  * - **latest update:**
    - 2024-03-28 05:08:17

Columns specification
~~~~~~~~~~~~~~~~~~~~~

.. list-table:: 
   :widths: 7 20 15 10 48
   :align: right 
   :header-rows: 1

   * - progr
     - column
     - units
     - type
     - description
   * - 1
     - time
     - UTC
     - datetime
     - UTC - datetime - Acquisition time
   * - 2
     - Quality
     - 0-1
     - float
     - Quality of the image 0-1 0=bad, 1=OK
   * - 3
     - X_cen
     - pixel
     - int
     - Position of the Solar centre on the X image axis [pixels]
   * - 4
     - Y_cen
     - pixel
     - int
     - Position of the Solar centre on the Y image axis [pixels]
   * - 5
     - R_sun
     - pixel
     - int
     - Radius of the Solar disk [pixels]
   * - 6
     - min
     - ADU
     - float
     - minimum value of the image [ADU]
   * - 7
     - Max
     - ADU
     - float
     - maximum value of the image [ADU]
   * - 8
     - mean
     - ADU
     - float
     - average value of the image [ADU]
   * - 9
     - std
     - ADU
     - float
     - standard deviation value of the image [ADU]
   * - 10
     - B0
     - deg
     - float
     - apparent tilt of the sun's axis of rotation with respect to the ecliptic [degrees]
   * - 11
     - data_name
     - char
     - string
     - the name of the file with the data
   * - 12
     - prew_name
     - char
     - string
     - the name of the full preview file
   * - 13
     - thumb_name
     - char
     - string
     - the name of the thumbnail file
