HOP 0156

abstract of observational proposal

Abstract of observational proposal: Using the strongest lines present in the EIS spectrum, we look for high frequency oscillations in active region loops. We use a small number of lines to try and keep the cadence of the observations as low as possible. Eclipse observations have indicated presence of oscillations with periods in the range of 6 - 30 s (Singh et al. 2009). We shall find out the signature of different modes of the fast acoustic oscillations. The measurements of high frequency oscillation period and other observational parameters, along with basic flux tube MHD theory will enhance the capabilities of coronal seismology. As a first run we would like to use Trace and as a follow up we would also like to combine the imaging capability of SDO (with fast multi wavelength imaging)as and when it is available for science operations. The additional observations with very hot flare lines will also explore the hot loop oscillations and give a chance to study its possible drivers.

We want to use the 40" slot so as to obtain images of the active region loops. We will look for material flows/waves in these loops at speeds appropriate to those of fast MHD waves.This will be complimentary to the images taken with SDO.

In addition we will measure densities in the active region loops. These densities are necessary in order to enable us to obtain estimates of magnetic field strength in the magnetic loops.The sit and stare at different locations (footpoints and loop top ) will allow us to study the dynamics with better precision. For EIS we would like one context raster, followed by a slot and then few sit and stare sequence at different locations.

request to EIS

arm_raster_ar duration 19m16s
arm_fastslot duration 15m24s
High_cadence_AR_dens duration 12m1s
High_cadence_AR_dens duration 12m1s
High_cadence_AR_dens duration 12m1s
Total Duration: 1h11m

raster: arm_raster_ar
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: 54 kBits/s

Species Wavelength (A) Total Counts/pixel/s) Window width
Ca XVII 192.82 57 56
Fe XII 195.12 424 56
He II 256.32 12 56
Mg VI 270.40 1 56
Si VII 275.35 2 56
Fe X 184.54 23 56
Fe XII 186.88 22 56
Fe XIII 203.8 46 56
Fe XIII 202.04 73 56
Fe XV 284.16 126 56
Ca XIV 193.87 16 56

raster: arm_fastslot
Slit: 40" slot
Window height: 176 pixels
Window width: 56 pixels
Exposure time: 4s
Rotation compensation: off
No. of exposure sets: 150
Total duration of study: 15m24s
Compression: JPEG(Q=98)
Data Rate: 81 kBits/s

Species Wavelength Type Window width (A)
Fe X 184.54 p 56
Fe XII 186.88 p 56
Ca XVII 192.82 c 56
Fe XII 195.12 c 56
Fe XIII 203.83 p 56
He II 256.32 c 56
Si VII 275.35 p 56
Fe XV 284.16 p 56

raster: High_cadence_AR_dens
Slit: 1" slit
Window height: 304 pixels
Exposure time: 5s
No. of exposure sets: 100
Total duration of study: 12m1s
Compression: lossless
Data Rate: 44 kBits/s

Species Wavelength Type Window width (A)
Ca XVII 192.82 c 32
Fe XII 195.12 c 32
Fe XIII 202.04 p 24
Fe XIII 203.83 p 32
He II 256.32 c 40

other participating instruments

TRACE:
TRACE will run a high cadence sequence of the active region chosen by EIS. As a minimum, each TRACE run should envelop every EIS run. A few additional images (white light, 195, 284, 1600) in the beginning and end of TRACE run should be included for context.
Channel: 17.1 nm channel
Cadence: 60 sec cadence
Exposure time : Slightly enhanced exposure times (>20 sec) are considered to enhance the signal-to-noise ratio of weak disturbances (about 10% in intensity) in extended loop systems (TBD in agreement with TRACE planner).