847 research outputs found
IRS-TR 12001: Spectral Pointing-Induced Throughput Error and Spectral Shape in Short-Low Order 1
We investigate how the shape of a spectrum in the Short-Low module on the IRS
varies with its overall throughput, which depends on how well centered a source
is in the spectroscopic slit. Using flux ratios to quantify the overall slope
or color of the spectrum and plotting them vs. the overall throughput reveals a
double-valued function, which arises from asymmetries in the point spread
function. We use this plot as a means of determining which individual spectra
are valid for calibrating the IRS.Comment: 9 pages, 3 figure
Abundant Methanol Masers but no New Evidence for Star Formation in GCM0.253+0.016
We present new observations of the quiescent giant molecular cloud
GCM0.253+0.016 in the Galactic center, using the upgraded Karl G. Jansky Very
Large Array. Observations were made at wavelengths near 1 cm, at K (24 to 26
GHz) and Ka (27 and 36 GHz) bands, with velocity resolutions of 1-3 km/s and
spatial resolutions of ~0.1 pc, at the assumed 8.4 kpc distance of this cloud.
The continuum observations of this cloud are the most sensitive yet made, and
reveal previously undetected emission which we attribute primarily to free-free
emission from external ionization of the cloud. In addition to the sensitive
continuum map, we produce maps of 12 molecular lines: 8 transitions of NH3 --
(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7) and (9,9), as well as the HC3N (3-2)
and (4-3) lines, and CH3OH 4(-1) - 3(0) the latter of which is known to be a
collisionally-excited maser. We identify 148 CH3OH 4(-1) - 3(0) (36.2 GHz)
sources, of which 68 have brightness temperatures in excess of the highest
temperature measured for this cloud (400 K) and can be confirmed to be masers.
The majority of these masers are concentrated in the southernmost part of the
cloud. We find that neither these masers nor the continuum emission in this
cloud provide strong evidence for ongoing star formation in excess of that
previously inferred by the presence of an H2O maser.Comment: 33 pages, 4 tables, 9 figures; ApJ Accepte
A 610-MHz Galactic Plane Pulsar Search with the Giant Meterwave Radio Telescope
We report on the discovery of three new pulsars in the first blind survey of
the north Galactic plane (45 < l < 135 ; |b| < 1) with the Giant Meterwave
Radio telescope (GMRT) at an intermediate frequency of 610 MHz. The timing
parameters, obtained in follow up observations with the Lovell Telescope at
Jodrell Bank Observatory and the GMRT, are presented.Comment: 2 pages, 1 figure, to be published in conference proceedings of "40
years of pulsars ..", replaced figure
Evidence for an interaction between the Galactic Center clouds M0.10-0.08 and M0.11-0.11
We present high-resolution (~2-3"; ~0.1 pc) radio observations of the
Galactic center cloud M0.10-0.08 using the Very Large Array at K and Ka band
(~25 and 36 GHz). The M0.10-0.08 cloud is located in a complex environment near
the Galactic center Radio Arc and the adjacent M0.11-0.11 molecular cloud. From
our data, M0.10-0.08 appears to be a compact molecular cloud (~3 pc) that
contains multiple compact molecular cores (5+; <0.4 pc). In this study we
detect a total of 15 molecular transitions in M0.10-0.08 from the following
molecules: NH3, HC3N, CH3OH, HC5N, CH3CN, and OCS. We have identified more than
sixty 36 GHz CH3OH masers in M0.10-0.08 with brightness temperatures above 400
K and 31 maser candidates with temperatures between 100-400 K. We conduct a
kinematic analysis of the gas using NH3 and detect multiple velocity components
towards this region of the Galactic center. The bulk of the gas in this region
has a velocity of 51.5 km/s (M0.10-0.08) with a lower velocity wing at 37.6
km/s. We also detect a relatively faint velocity component at 10.6 km/s that we
attribute to being an extension of the M0.11-0.11 cloud. Analysis of the gas
kinematics, combined with past X-ray fluorescence observations, suggests
M0.10-0.08 and M0.11-0.11 are located in the same vicinity of the Galactic
center and could be physically interacting.Comment: Accepted for publication in the Astrophysical Journa
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