# MSAM Data Products at LAMBDA

Product Name
June 1992 Flight
Mission
MSAM

Description

A tar file is provided containing the following files:

README.tex: A copy of this description.

2beammap.dat, 3beammap.dat: Antenna pattern maps. See below for format. 2' is for single difference demodulation, 3' is double difference.

cmbr\_2ba.dat, cmbr\_2bb.dat, cmbr\_3ba.dat, cmbr\_3bb.dat: CMBR data. See below for format. Units are microKelvin deviations in 2.73K blackbody. As above, 2b' is single difference demodulation and 3b' is double difference. a' is the first half of the flight (RA from 14.44 to 16.89) and b' is the second half (RA from 17.18 to 20.33).

dust\_2ba.dat, dust\_2bb.dat, dust\_3ba.dat, dust\_3bb.dat: Dust data. See below for format. Units are $10^6$ times optical depth at 1 icm, assuming the emissivity scales as $\nu^{1.5}$. These data principally depend on our 22.5 icm channel, so it would be more reasonable to multiply these numbers by $22.5^{1.5} = 107$ and call them optical depth at 22.5 icm.

Format of beammap files: These files contain the beam map sampled on a grid. The first line has the dimensions of the grid in the X and Y directions. The remaining lines have the form (X-coord, Y-coord, beam-amplitude). X-coord and Y-coord are in degrees.

Format of data files: Comment lines begin with `!'. Otherwise each line of this file represents one observation of the sky. There are six numbers on each line, which are:

1) Zero (ah, history).

2) Observed data (CMBR fluctuation for cmbr files, dust optical depth for dust files). Specifically, this is $${1\over\Omega_H}\int d\Omega\,H(\Omega)D(\Omega),$$ where $H$ is the antenna pattern appropriate for the demodulation (in the beammap files), $D$ is CMBR anisotropy or dust optical depth respectively, and $\Omega_H$ is 0.18 deg$^2$ for cmbr and 0.19 deg$^2$ for dust. NB: the normalization of these numbers depends on the normalization of the antenna pattern --- do not attempt to interpret them without looking at the beam map.

3) X (degrees). X and Y (below) are the location on the sky of the center of the antenna pattern. Declination $\delta = 90^\circ - \sqrt{X^2 + Y^2}$ and right ascension $\alpha = \tan^{-1}(Y/X)$.

4) Statistical weight of data.

5) Y (degrees). See X above.

6) Twist (degrees). This is the angle between the X axis of the X/Y coordinate system described above and the X axis of the beammap.

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