AR9787 January 20th - 28th 2002

The AR9787 dataset is ideal for helioseismic analysis as it is long with a good dutycycle and consists of Dopplergrams, magnetograms and intensity continuum. The sunspot is relatively large and isolated, not polluted by any nearby strong magnetic field. The data was tracked and mapped by T. Duvall and analyzed by L. Gizon.

The Data: The MDI data is stored as tracked , Postel projected FITS data cubes extracted from MDI full disk Dopplergrams, magnetograms and the intensity continuum. Each Dopplergram and magnetogram datacube contains 24 hours of data. The intensity cube holds one 2D array for each 6 hours of the 9 day's observation.

Time: 24 hours, from midnight until 23:59 each day - 9 days - 20th January 2002 until 28th January 2002 during Carrington rotation 1991. Tracking coefficients:     a0 = -1.50000e-02     a2 = -3.39000e-01     a4 = -4.85000e-01

Resolution: 0.12 deg / pixel, ~ 0.002 Solar radii / pixel, ~ 1.45 Mm /pixel

Dimensions: 512 x 512 x 1440 pixels

MDI Level: lev1.5. - Sample MDI header

Note: The intensity images are one every 6 hours.

New! Download Quiet sun comparison regions either side of AR9787, and AR9787 calculated by R. Bogart.

TRACE data is also available for AR9787.

Sunspot Evolution

Averaged Dopplergram (top row), intensity (middle row), magnetogram (bottom row) for the 9 days of AR9787 MDI observation:

Quick look movies (click on images for the movie)

MDI intensity continuum

MDI line-of-sight Doppler velocity

MDI line-of-sight magnetic field

The continuum average of the sunspot over 9 days

Position: Heliographic longitude (phi_c) and latitude (lambda_c) of the umbra. The FITS file (right click) of these coordinates in pixels.

Size: The boundaries of the umbra, penumbra and moat boundary as determined from a 9 day, azimuthal average.

Moat Flow: slices of B at latitude= lambda_c (left) and at longitude = phi_c (rght) in time. Saturated at +/-200 Gauss. Note the moving magnetic features.

Radial Moat Flow: A 9 day average of the radial moat flow (m/s) from center of spot obtained by tracking moving magnetic features (MMF).

Sunspot Classification:

Date	Location	Magnetic Type	Z	Area	LL	NN
20.01.02	S07E59	Alpha	Cko	0360	10	06
21.01.02	S07E46	Alpha	Cko	0420	10	06
22.01.02	S07E32	Beta	Eko	0430	11	07
23.01.02	S06E19	Beta	Dko	0400	07	13
24.01.02	S07E06	Beta	Dki	0440	08	10
25.01.02	S06W06	Beta-Gamma	Dko	0470	10	10
26.01.02	S09W21	Beta-Gamma	Dko	0400	06	08
27.01.02	S09W33	Beta	Dko	0410	10	12
28.01.02	S08W48	Beta	Cko	0450	05	05

Sunspot definitions

Farside: AR9787 is seen in the southern hemisphere on the farside approaching the Eastern limb. From the farside images, it appears to have coalesced from two or three smaller magnetic regions to form the large sunspot seen on the near-side. It endures on the farside for a further 5 days after passing the Western limb (see Stanford MDI farside Images).

SFT Potential field overlying AR9787 on 24th January 2002 from the SFT data. A sample header is provided.

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