XRT:
2007-12-21T07:25:00 to 2007-12-21T10:47:54
Science Goal: CORE: Synoptic SOT Irradiance Scans, CORE: SOT continuous magnetic field observations for investigating mechanisms responsible for XBPs and QS dynamics
Program: TI_just_after_OP_Upload
Target:
xcen=-1000000000 ycen=-1000000000
Instrument: XRT
HOP/JOP: 0
Description:
Daily Note: Weekly meeting XRT table upload, originally scheduled for pass 2, switched to pass 3 at request of XRT CO. XRT * Active Region thermal/DEM studies and high cadence movie (AR is TBD). * Continue flare detection mode. * Support HOP 53 (QS and XBP), if no ARs are present on the disk. EIS * HOP 53 (for two days as required) SOT * HOP53
Request to XRT HOP Number 0046:
Other Instruments: eventual use of ACRIM and SORCE TIM irradiance measurements during analysis phase. No specific requests for coordinated operations since these instruments operate continually.
Scientific Objectives: Scientific background: The total solar irradiance varies by about 0.1% over the course of the solar cycle, primarily due to the influence of magnetic structures such as sunspots and faculae on the photospheric spectral irradiance. Short-term irradiance variation (on the scale of days-to- months) is well understood to be due to the balance of sunspots and facular areas as they cross the disk. However on the decadal scale of the solar cycle, questions remain as to why the irradiance variation can lead and/or lag the active region count over the course of the cycle. Explanations ranging from changes in the solar diameter in response to magnetic flux storage in the convection zone to changes in the surface area of the photosphere due to F-mode modulation have been put forward. Seeing-free observations of both granulation and magnetic flux on a large range of scales are now possible with the SOT SP/FG instrument combination. We propose to observe with SOT on a regular basis throughout the rise of Cycle 24 in order to better understand the variation of irradiance with rising flux levels in the photosphere. On 07-March-2007 we performed a test program which produced a N-S scan of the central meridian with full SP normal maps at 12 positions. In a separate program (08-March-2007) we produced E- W scans of the +15 and -15 deg. latitude ""active region"" belts with BFI continuum filtergrams and NFI Fe I 630.25 nm magnetograms. Both of these programs produced unique data that are not possible to obtain from any other visible light solar instrument. If performed on a regular basis and ultimately analyzed with the data from the total irradiance measurement satellites such as ACRIM and SORCE, these observations have the potential to reveal new and important aspects of the relation between solar irradiance and magnetic flux emergence over the solar cycle. Objective: Measure large-sample statistical granulation properties such as size and contrast in three continuum bands along with both line-of-sight and vector magnetic field measurements for a variety of disk positions over the course of Cycle 24. Ideally we would like to have full-disk observations of these properties, but since the SOT field- of-view is limited, the number of disk positions observed is limited to the number of individual pointings that are practical in one observing period.
Request to XRT HOP Number 0053: Thin Al/Poly sub-field readout at each pointing position.
Other Instruments: NONE
Scientific Objectives: Previous magnetic-field observations (/w 1-2 arcsec spatial resolution, longitudinal only) shows that magnetic cancellation is involved in many XBPs and magnetic emergence in a limited number of XBPs (e.g., Harvey et al.) Priest and Parnell (1994) proposed a magnetic canceling model for explaining the overall evolution of XBPs. However, this model has not yet been confirmed with observations. SOT has not yet performed magnetic-field observations suitable for investigating mechanisms responsible for XBPs (see Kotoku et al. 2007 PASJ). The biggest problem in the observations made so far with Hinode is that continuous SOT observations are available only in a few - several hours, which is much shorter than the lifetime of XBPs (8 hrs for small typical XBPs, 48hrs for bigger XBPs) and time-scale of small-scale magnetic field evolution (Schrijver et al. 1998). We are lack of observations with continuous a-few days tracking of a quiet region with Hinode SOT coodinated with XRT and EIS.
