Pre-shipment review
On 2006 July 31st, a pre-shipment review of the LABOCA instrument and BoA2S software took place in the lab. All possible observing modes have been tested; 16 MB-FITS files were produced, including 3 with CFITSIO error problems. One file was acquired with a wrong synchronisation between the backend clock and control system. The other 12 can be read in and processed; they are listed below:
Filename |
Source |
Scan mode |
# subscans |
Scan type |
APEX-10060-O-PP.C-NNNN-YYYY |
test |
RASTER |
2 |
CAL |
APEX-10061-E-077.C-0123-2006 |
SKYDIP |
RASTER |
5 |
SKYDIP |
APEX-10062-E-077.C-0123-2006 |
Alfa-Ori |
RASTER |
2 |
ONOFF |
APEX-10063-E-077.C-0123-2006 |
Alfa-Ori |
RASTER |
3 |
FOCUS-Z |
APEX-10064-E-077.C-0123-2006 |
Alfa-Ori |
OTF |
2 |
POINT |
APEX-10065-E-077.C-0123-2006 |
Alfa-Ori |
OTF |
5 |
MAP |
APEX-10067-E-077.C-0123-2006 |
Alfa-Ori |
OTF |
13 |
MAP |
APEX-10068-E-077.C-0123-2006 |
Alfa-Ori |
RASTER |
9 |
MAP |
APEX-10070-E-077.C-0123-2006 |
Alfa-Ori |
RASTER |
1 |
MAP |
APEX-10073-E-077.C-0123-2006 |
Alfa-Ori |
RASTER |
4 |
MAP |
APEX-10074-E-077.C-0123-2006 |
Alfa-Ori |
RASTER |
1 |
MAP |
APEX-10075-E-077.C-0123-2006 |
Alfa-Ori |
RASTER |
1 |
MAP |
Good and bad channels
Only the first 80 backend channels were connected. In all these data, we observe three different behaviours:
- noisy channels: 6 channels (#24, 29, 33, 34, 35 and 40) show noise one order of magnitude higher than the other ones. This may be backend channels which are not actually connected to any bolometer
- dead channels: in addition to channels 81 to 295, 16 channels (#18, 22, 28, 30, 32, 37, 46, 47, 51, 53, 59, 60, 64, 66, 69, 74) show almost no signal (variations are within +/- 2 counts, i.e. only digitizing noise)
- good channels: the other 58 channels (70%) have a normal behaviour
Calibration
Scan number 10060 was a "calibrate('hot')" observation: 1st subscan was acquired with the instrument looking at a plate at room temperature, and 2nd subscan was obtained with the instrument looking at a bath of liquid nitrogen (77K). In all good channels, the signal and its power spectrum look like this:
The strong 1/f component is mostly due to the gap in the signal between the two subscans. When looking only at one subscan, the power spectrum of a typical good channel looks like this:
Peaks are seen at frequencies of 30.5, 39.0 and 80.5 Hz. Smaller peaks appaer at 77.8 Hz in all channels, and at various other frequencies, depending on channel.