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Daily Reports
June 11, (Sunday)
08h00 : Start again. Opacity is stille high (0.7). Observing Mars. 01h00 : opacity still around 1. Tau225 plot is not updated because linear fit fails (Joaquim dixit) but we can check the exponential fit in
In general, very unstable conditions during daytime (mainly anomalous refraction), clearly visible in the quality of the recovered beams (fig. below). Considerable better during the night. Before midnight, the cryostat looks to be working well, and the array is at ~200mK. We plan to observe a few quasars throughout the night with a "standard" script, with 2.98 Hz HWP rotation. Our plan (for the day) is to observe : * 23h-07h: A. Bracco, J.F. Lestrade, & C. Romero KID Sampling Freq. HWP Mechanical Rot. Freq. Tel. Scanning Speed 47.7 Hz 2.98 Hz 25"/s 47.7 Hz 3.97 Hz 30"/s 47.7 Hz 1.49 Hz 17"/s 23.3 Hz 1.49 Hz 17"/s
* We performed the optical alignment check with Santiago. The alignment is good so we did not change the position of the mirrors. We also checked the alignment of the HWP. * The electronics of the HWP wheel is working nominally. We tested different speeds without problems. * Juan Penalver tested the temperature control of the cabin and setting the temperature at 12°C for few hours. Tomorrow before starting the observation we will switch on the turbo pump after setting the temperature of the cabin to 10 or 12°C.
* Aina, Alessia, Nicolas and Andrea arrived at the telescope. The idea is to prepare carefully the observations starting on Thursday since the last observation in polarisation performed with NIKA2 was more than a year ago. Nicolas Aina and Alessia worked on the polarisation pipeline, Andrea set up the polarisation facilities and check their proper operation. * The temperature of the mixing chamber is about 265 mK without using the turbo molecular pump. The pressure on P101 is slowly increasing showing that the trap is saturating. It does not seems to be a big problem because the slope is about 40mbar/day meaning that probably we can observe until next tuesday without switching the trap. June 10, (Saturday)
18h00 : We stop the observations: very poor weather. Morning : Observations of Mars at 300mK with a very high tau (about 0.8) 05h30 : Pump on until 07h30 then stop again. 02h05 : sharp raise of temperature from 187mK to 245mk over the next half hour. we did not lose the tuning. We woke up Andrea who turned the pump off. We continue in these conditions. 00h30: The atmosphere and instrument again seem stable. In particular, the histogram of PS amplitudes (in the "kid monitoring" window) is indicative of stable atmosphere conditions, despite relatively high opacities (tau_225 ~0.5). June 9, (Friday)
Example of noise spectrum obtained with HWP on at nominal configuration (2.98 Hz mechanical frequency), together with the corresponding configuration of the wheel control (to be remembered for future campaigns). June 8, (Thursday)
10h00: Start of the observations. The plan of the day is to start the observations on a planet (Mars) to characterize the instrumental polarization (i.e intensity to polarization leakage effect). We want also to characterize the noise due to the HWP modulation which is peaked at harmonics of the HWP rotation frequency. Running faster with the HWP means to have access to faster scanning speeds of the telescope but we could have a noise not trivial to subtract from the timelines. In order to find a compromise between this two issues we decided to make tests doing observations with different parameters as follows:
June 7, (Wednesday)
June 6, (Tuesday)