Subject: CorMag@LSO news
From   : Jan Rybak <choc@ta3.sk>
Date   : 12.10.2015 11:53
To     : Silvano Fineschi <fineschi@oato.inaf.it>
         Gerardo Capobianco <capobianco@oato.inaf.it>
         Kavka Juraj <kavka@astro.sk>

DONE list:

- 2 new observing programs written: based on suggestions of Silvano
        given to me in Brussels, the idea was to test whether we can see
        at least unpolarized green line emission using CorMag@LSO

  obs_prog_002:  1 wavelength  only - 530.28nm
                 datatypes: DARK,FLAT,DATA

  obs_prog_002:  2 wavelengths only - 530.28 and 530.08 nm
                 datatypes: DARK,FLAT,DATA

- a little improved photometric reduction procedure written including
  a correction for the relative optical system throughput ~ wavelength and
  several checks of the data reduction procedure added

- new observations made by our assistant Juraj Kavka:

  1/ obs_prog_002:  1 wavelength  only - 530.28nm
     date/directory: 20151003_obs_prog_002

  2/ obs_prog_003:  2 wavelengths only - 530.28 and 530.08 nm
     date/directory: 20151003_obs_prog_003

  3/ obs_prog_001: 11 wavelengths 530.13,530.16,...,530.43 nm
     date/directory: 20151003_obs_prog_001: only DARK,FLAT

  4/ obs_prog_001: 11 wavelengths 530.13,530.16,...,530.43 nm
     date/directory: 20151002: all datatypes but CALI without pre-polarizer

  5/ obs_prog_001: 11 wavelengths 530.13,530.16,...,530.43 nm
     date/directory: 20151001: all datatypes but CALI without pre-polarizer

  6/ obs_prog_001: 11 wavelengths 530.13,530.16,...,530.43 nm
     date/directory: 20150922: all datatypes but CALI without pre-polarize

- An analysis of these data sets performed led to some new results:

1/ the latest observations performed by our observing assistant
   Juraj Kavka do show still some reflections in the image due to
   air bubble problem or other reasons.
   Illustrative images:
   https://www.astro.sk/~choc/open/cormag/20151003/actual_status_of_reflections/

   Therefore I shall go up to the observatory to check the reasons
   and to repair if possible. Listed are possible reasons to be
   evaluated: orientation, azimuth and inclination of the IR filter,
   inclination of the CCD camera chip relatively to the optical axis

   We need clear sky for these tests. I shall wait for it!

2/ from the observing run chopping between the continuum and line center
   (obs_prog_003) we can see the GREEN LINE EMISSION in principle!
   According to the item 1/ given above this can not be the final
   confirmation of reaching our goal but it seems promising.
   At the moment it is for me hard to separate effect of the reflections and the
   solar emission. Nevertheless I can confirm that the typical core-continuum
   signal is ~5000 counts in 0.1s exposure for a bright active region loops
   (2015/10/03 PA=250 degrees).
   See enclosed image: CorMag_20151003_085109_diff_core-cont.jpg
   Example of 100 continuum, line core and difference images:
     https://www.astro.sk/~choc/open/cormag/20151003_obse_prog_003/imas/
   Example of 100 difference images: penumbra.astro.sk
   /RAIDofsF/choc/lso/LSO_cormag/20151003_obse_prog_003/imas/diff_line-conti/

3/ Watching a series of the line_core-continuum difference images it can be
   seen that the actual 'green corona' image is highly dependent on actual seeing
   actions shifting the line_core image and/or the continuum image relatively
   to the Lyot stop (artificial moon). Some images look reasonable when the effect
   of seen is small, some are crazy when seeing shifts these images considerably.
   See images listed in item 2/.

My todo list:

1/ to try to correct the remaining reflections in CorMag@LSO instrument
2/ to prepare procedure for determination of the absolute energetic calibration
   of the system - ABSO data type in order to calibrate the emission in
   energetic units
2/ to get more obs_prog 003 and obs_prog 001 observations with larger
   occultation of the solar disk (35"->70") in order to allow longer
   exposure times