HOP 0164

abstract of observational proposal

We intend to perform spectroscopy of the solar corona in the green and red emission lines simultaneously with a frequency of about 0.2 Hz from Easter Island during 11th July, 2010 total solar eclipse. The aim of the experiment is to detect high frequency oscillations in the solar corona. A 30 cm two mirror system (coelostat) will be used to direct the sun and coronal light to a 10 cm objective to form an image of the corona on the slit of the Littrow type spectrograph. A 14 cm objective will collimate the beam and image the spectrum on the two CCD cameras. Broad band filters will be used to separate the orders. A grating with 600 lines per mm blazed at 2 microns will provide a reasonable dispersion (2 Angstrom per mm) to determine the emission line profiles. Two CCD cameras of 1K x 1K format with pixel size of 13.0 x 13.0 microns will be used to take the images. The CCD chip will be back illuminated for high efficiency and camera will operate in frame transfer mode to obtain data with high frequency. The read out is in 10-bit format at 10 MHz. With this ground based experiment we would like to have a simultaneous campaign with Hinode.
Using the strongest lines present in the EIS spectrum, we look for high frequency oscillations in active region loops (if they are present off-limb) otherwise we will point in the polar region to look for plume and inter-plume region. We use a small number of lines to try and keep the cadence of the observations as low as possible. Recent Eclipse observations have indicated presence of oscillations with periods in the range of 6 - 30 s (Singh et al. 2009). We also find signatures of Alfven like waves from the variation of line width studies. We intend to verify this with this joint spectroscopic campaign from Hinode and our ground based experiment.

request to EIS

If we target an AR off-limb then we would like to run the following studies
arm_raster_ar duration: 19m 39s
High_cadence_AR_dens duration: 12m 24s (this should run during the totality: from 20:08 UT)
arm_raster_ar duration: 19m 39s
Total Duration: 51m 42s

Study name: arm_raster_ar (study no: 400)
Window width: 56 pixels
Window height: 400 pixels
Exposure time: 25s for AR
Slit: 2" slit
Number of fine mirror steps: 40
Rotation compensation: Off
Total duration of study: 20m
Compression: lossless
Data rate: 51 kBits/s
Data volume: 60 Mbits

Study name: High_cadence_AR_dens (study no: 402)
Slit: 1" slit
Window height: 304 pixels
Exposure time: 5s
No. of exposure sets: 100
Total duration of study: 12m 24s
Compression: lossless
Data rate: 43 kBits/s
Data volume: 32 Mbits

Alternative Request to EIS
If we choose the polar region then we would like the following study
arm_loop_ne_slit duration: 24m 59s
CH_density duration: 1h 2m 46s
Total Duration: 1h 27m 45s

Study name: arm_loop_ne_slit (study #423)
Slit: 2" slit
Window height: 400 pixels
Exposure time: 45s
No. of exposure sets: 30
Total duration of study: 24m 59s
Compression: lossless
Data rate: 21 kBits/s
Data volume: 31 Mbits

Study name: PRY_CH_density (study id 268)
Window height: 200 pixels
Exposure time: 100 s
Slit: 2" slit
Number of raster pointings: 34
Total duration of study: 1h 2m 46s
Compression: lossless
Data rate: 5.1 kBits/s
Data volume: 20 Mbits

remarks

Eclipse and Observation Timing
Start of partial eclipse (C1) : 2010/07/11 18:40:54.1 039.8° 012.6°
Start of total eclipse (C2) : 2010/07/11 20:08:44.0 039.6° 346.1°
Maximum eclipse : 2010/07/11 20:11:07.1 039.5° 345.4°
End of total eclipse (C3) : 2010/07/11 20:13:29.7 039.3° 344.7°
End of partial eclipse (C4) : 2010/07/11 21:34:28.2 031.4° 323.8°

Ideally we would like to have a raster scan of an AR loop system (if any) during the partial phase and during totality run the sit and stare [Study name: High_cadence_AR_dens (study no: 402)] observation of about 12 minutes centering around the totality phase i.e. 20:11.
If we do not get any loops off-limb then we would prefer to run the polar study, with the same philosophy, created a raster scan followed by a sit and stare during totality phase, so that it is closer to our ground base observational timing.