COSMOCAL PROJECT
saturday - september 28 2024
third day of measurements:
- all observational time was dedicated to the alignement
- we run multiple ON scans, changing the azimuth and the elevation of the antenna, keeping the source fixed
- we estimated (through on-the-fly intensity polarization maps) that the best alignment is found when the antenna is set with offsets of -2' in Az and -15' in El
friday - september 27 2024
second day of measurements:
- acquired ON-OFF scans of the mm source
- we changed the polarizer's orientation by the following angles: 90º, 105º, 120º, 135º, 150º, 165º, 180º, 195º, 210º, 225º, 240º, 255º, 270º, 285º, 300º, 315º, 330º
- we acquired files to check the noise level of the mountain, the pws of the source with and without the chopper and finally with the hwp
- we had issues with the tuning: within every scan a tuning was done, so we observed a flat interval in the signal
thursday - september 26 2024
in the first day of measurements, we performed the following activities:
- with the source off, the hwp placed on the optical path but not spinning, we pointed the sky (close to the north pole) and then a source: on it we performed focus and pointing and applied corrections
- we moved to the mm source by running track command on pako, using the coordinates known from holography
- on the acquisition software, we looked for resonances and tuned them (with hwp still off); the saved parameter was already well adapted to the mountain load
- we started spinning the hwp at nominal 3Hz frequency
- we switched on the mm source along with the chopper, modulating at 1Hz
- at first, we saw no signal, but then we realised that the source's polarizer was set to 0º, hence minimising the signal, so we turned it to ~45º the signal appeared, with the correct hwp + chopper modulations
at this point, we started procedure to maximise the signal, by tilting the mm source in Az and El : here came some problems --> lost resonances, irregular signal (appearing and disappearing) and we could not go back to initial situation
- so we closed the vertex to see if the problem was in kids or in real signal, and we saw a constant signal of ~2kHz
- we opened the vertex again, tuned the resonances and the situation was quite stable again, so we took 3 ON-OFF scans