MSAM Data Products at LAMBDA

Product Name
June 1992 Flight


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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