HOP 0272

abstract of observational proposal

We are proposing for a new Hinode SOT SP observation in order to support our research, and a soon-to-be submitted NASA proposal (HSR deadline of Oct 30th) regarding the identication of MHD waves and their amplitudes, frequencies and propagation. The NASA HSR proposal has myself as PI, Paul Cally, Paul Rajaguru, Charles Baldner and Phil Scherrer as investigators.

We plan to use Cally's numerical simulations of acoustic wave conversion into MHD waves to guide our observations and interpret the results. We will utilize local helioseismology of the observed sunspot in HMI data to determine acoustic mode absorption. We will use HMI 12-minute vector magnetic field maps for the average and general geometry of the field in the vicinity. We want to analyze the SOT SP data to examine what temporal variations exist in the inverted data and Stokes vector that could be informing us of the existence and nature of MHD waves. Optionally, we would like to include IRIS data of Mg II, C II and Si IV lines to correlate with the Doppler and magnetic fluctuations observed in SP.

request to SOT

*Target of Opportunity observations of a sunspot with the slit across the spot.

*Fast Map observing mode which is a 3.2 second cadence per slit step with a 0.3 arc sec per slit step. (Dynamic mode or very fast map mode is 1.6 seconds and 0.15 arcsec per slit step so fast map mode essentially bins two dynamic mode positions.) Discussion: I realize that using a Fast Map would mean the field of view would only be 5 arcsec wide. I am hesitant to use the even faster map mode as it reduces signal to noise and makes a difficult detection even more difficult. However, if the enlarged field of view of the very fast map is better for stabilizing the correlation tracker, or ensuring that at least some of the field of view is consistent over the course of 6 hours as there may be drift, then we can run that.

*Repeating raster so that the cadence of the raster is 60 seconds or less (meaning 18 or less steps if using a fast map configuration).

*DURATION: 6 hours to obtain decent frequency resolution

*Need to observe inclined field so penumbra should be observed as well as the umbra. Ideally both the umbrae and two sides of the penumbra would be observed. Height along the slit should be 82 arcsec minimum to allow accurate removal of drifts.

*Perhaps reset correlation tracker every hour or two as the stability might be worth the 1.5 minute data gap. ?

other participating instruments

Optional (but desirable) IRIS: 1 hour of data in Mg II, C II and Si Iv lines.
To ensure overlap with SP, it is preferrable to roll IRIS by 90 degrees. An 8 step sparse raster (1 " steps with 4 s exposure times) would result is a scan of 8 x 120 " with a cadence of 43 seconds summed by 2 in the spectral dimension to boost the FUV signal/noise. The IRIS OBS id for this would be 3820257177. This will give C II, Si IV and Mg II h/k slit jaw images with a cadence of 21 seconds for each of the filters.