Previous Article
Next Article
Table of Contents

NIM Available to Visitors (1Mar93)
(from NSO, NOAO Newsletter No. 33, 1 March 1993)

The Near Infrared Magnetograph (NIM) will become available to visiting
observers during the second quarter of 1993. Designed to map magnetic
field strength in the active solar photosphere, NIM is a Stokes
spectropolarimeter that exploits the high Zeeman sensitivity of the
line Fe I 6388.64 cm-1 (15648.5 A, Lande g = 3.00, Xe = 5.36 eV) to
measure the vector magnetic field. For B > = 850 G, the magnitude of the
field is derived, without adjustable parameters, from the complete
splitting of the Zeeman components. The relative strengths of the
Stokes components indicate the direction of the field. The absolute
strength of the polarized signal depends on the areal filling factor,
inclination, continuum contrast, and line strength of the magnetic flux
tubes within the angular resolution element.

NIM builds up a two-dimensional array of polarized line profiles by
scanning the solar image across the slit of the 13.7-m vertical
spectrograph of the McMath-Pierce Telescope on Kitt Peak.  The spatial
and spectral sampling frequencies are approximately 1 arcsec per pixel
and 0.06 (0.025 cm-1) per pixel. The detector is a 256 x 256 indium
antimonide array. At each slit position, 8 polarization pairs for each
Stokes parameter (e.g., +- V) are acquired at 7 Hz, averaged, and
recorded in FITS format on disk. A 4 x 4 arcmin map is acquired in about
20 minutes.  The data on disk are finally recorded on Exabyte tape or
DAT.

Proposals to use NIM may be made quarterly using the standard NSO form
(deadlines: 15th of January, April, July, October). For more
information about NIM, please contact Doug Rabin.

Dave Jaksha, Greg Kopp, Chuck Mahaffey,
Claude Plymate, Doug Rabin, Jeremy Wagner

Previous Article
Next Article
Table of Contents