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Astron. Astrophys. 332, 71-76 (1998)

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2. Observations

Observations were made as part of the TMGS (" Two Micron Galactic Survey") (Garzón et al. 1993; Hammersley et al. 1994; Calbet et al. 1995) carried out by the IAC (Instituto de Astrofísica de Canarias). The aim is the survey in the K-band of the galactic plane with a 15 arcsec resolution and a 10.5 limit magnitude (Calbet, 1993); therefore, individual stars are observed, so that position and magnitude are determined for each star. Before the observations made for this work, the survey was mainly devoted to the galactic centre and the order of scans was altered to observe the [FORMULA] galactic longitude zone, where the Local Arm lies. The original purpose was the study of the north warp in the near infrared, but in this zone the emission is dominated by the Local Arm. The obtained data were therefore used to describe the NIR Local Arm.

For TMGS the 1.5 m NIR "Carlos Sánchez" telescope is used. The telescope is located in Tenerife at 2400 m altitude. Scans are obtained by switching off the right ascension telescope motor, and thus constant declination scans are obtained, taking advantage of terrestrial rotation. We do not further describe the observation techniques and the system for data acquisition and processing as this has been extensively done on previous occasions (Hammersley 1989; Garzón et al. 1993)

In Fig. 1 we show the scans used in the present work. An interpolation technique was carried out in order to have values at each point in a mesh (also reproduced in the figure) with constant [FORMULA] and constant [FORMULA]

[FIGURE] Fig. 1. Zone of the galactic plane observed. We represent the 9 scans at constant declination and the mesh where we interpolate with constant [FORMULA] and constant [FORMULA].

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© European Southern Observatory (ESO) 1998

Online publication: March 10, 1998