How to Find Out How Much Data Disk Space Remains

To find out how much disk space there is on CACCC's data disk use the /status page on CAMON. The value shown is % of the total disk space (30GB) being used. Data is collected at the maximum rate when spectral line mode pulsar observations are being made. In this case, the data rate is usually less than 90 Megabytes per hour. For a twelve hour observation, then, you need fewer than about 1000MBytes.

The data rate for your configuration can be approximately calculated by:

$$r = 0.004\ \frac{s\ c\ p\ f\ n\ b\ bins}{t\ m}$$ (9)

where:

$r$ = the data rate in MBytes per hour

$s$ = data stream (4 bytes)

$c$ = complex components (amp. + phase = 2, or real and imaginary)

$p$ = polarisations (XX, XY, YY, YX; max. 4)

$f$ = frequencies (max. 2)

$n$ = number of channels + 1 (33, 513, 1025, etc; max. 2049)

$b$ = number of baselines (max. 15)

$bins$ = the number of bins used (1 unless in pulsar binning mode)

$t$ = integration time in seconds (5, 10, 15, 20, 30)

$m$ = number of cycles averaged
Note: $b$ = $a(a$ - 1)/2 where $a$ = number of antennas

Data is archived automatically and support staff delete data regularly to ensure that observers always have plenty of space. If you do not have enough disk space, ask the Duty Astronomer to delete some of the archived data using the delete_data task on FURIOUS.