ABSTRACT

We present maps at 30, 40, 144 GHz of a portion of the Galactic Plane centered about a declination of -60° (approximately 280 < l < 305 and -8 < b < 4). The maps have resolutions ranging from 0.2° to 0.9° and are optimized to detect unresolved source emission. We present flux densities and temperatures for six regions bright at millimeter wavelengths. Two regions, visible only at higher frequencies, suggest an inverse spectral function.

INTRODUCTION

• We characterize emission from unresolved and localized millimeter-bright regions.
• Our observations include the Carina Nebula, several well-known HII regions and star clusters.
• Some substructure visible in IRAS 100 mm is not resolved in the MAT beams.
• Since not all objects could be positively associated with an existing label, we denote each bright region with a number from 1 to 6.
• MAT 5 and MAT 6 are both composed of two unrelated objects whose separation is resolved at 144 GHz. In each case, one of the objects has an inverted spectrum.

OBSERVATIONS

• Observations presented here were carried out at 5200 m from Cerro Toco, Chile from August 30, 1998 to October 14, 1998.
• Each day, MAT viewed a band about the South Celestial Pole of constant mean declination.
• MAT is a 0.85 m diameter aperture telescope with three frequency bands (30, 40, 144 GHz) and using 8 channels of HEMT and SIS amplifiers. It is steerable in azimuth but fixed in elevation.
• A flat mirror sweeps the beams with an amplitude of 3° on the sky in a sinusoidal pattern at 3.7 Hz.
• The calibration and antenna patterns are measured in the field through daily observations of Jupiter. All antenna patterns are well approximated by Gaussian profiles.
• Click here for the location of the MAT observations superimposed on the DIRBE 240 mm full sky map. The inset details this region showing 100 mm bright contours as seen by IRAS. This file is in PDF format.

MAPS

• After atmospheric filtering, the daily observations were co-added to produce final images of the region.
• Each map is composed of 10 to 15 observations.
• Click here for representative plots of the Galactic region at 30, 40, and 144 GHz as well as large-scale plots of the source regions.
• The overlaid IRAS 100 mm intensity contours demonstrate pointing and additional bright sources in the region not seen by MAT.

OBJECTS

• MAT 3 is dominated by emission from the Keyhole Nebula that contains the Carina Nebula. This region contains a second bright source, IRAS 10414-5919.
• Both MAT 5 and MAT 6 contain two IRAS-bright sources which are clearly seen at 144 GHz (MAT 5a and MAT 5b). However, the 30 and 40 GHz observations indicate an inverted spectrum with spectral index of b >= 2.0 for MAT 5a and b >= 1.5 for MAT 6a where S ~ v^b. This is consistent with the classical spectra of compact HII regions where S ~ v².

RESULTS

• The table contains temperature and flux within a circle of one and two beam widths.
• No entry for a channel implies the source is not in the field of view or is below the measurable flux limit.
• For each frequency we report averaged values over all channels.
• Errors do not include a 5% systematic uncertainty in the brightness temperature of Jupiter.

Here is the Entire Project Poster