2007-10-11T00:20:01.000Z http://sot.lmsal.com Mr. Sam Freeland Lockheed Martin Solar and Astrophysics Laboratory (LMSAL) http://www.lmsal.com Lockheed Martin Advanced Tech Center, 3251 Hanover Rd, O/ADBS, B/252, Palo Alto, CA 94304 null null HINODE XRT KANO, Ryouhei KOTOKU, Jun'ichi NISHIDA, Keisuke 0 7 -1.035 0.055 526.643 526.643 2007-10-08T08:05:00.000Z 2007-10-08T19:29:28.000Z -1.035 0.055 Synoptic SOT Irradiance Scans TI_just_after_OP_Upload Daily Note: none; 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. ivo://sot.lmsal.com/VOEvent#2007-10-08T07:06:30Z