search

MWATelescope / mwa_hyperdrive

Calibration software for the Murchison Widefield Array (MWA) radio telescope
https://MWATelescope.github.io/mwa_hyperdrive
Mozilla Public License 2.0
92 stars 4 forks source link

No ATTEN_DB in solutions #32

Open d3v-null opened 3 months ago

d3v-null commented 3 months ago

Sometimes people will apply solutions from one observation to another nearby observation, however these do not always have the same analogue attenuation. This is useful metadata to have in a calibration solution

See: ATTEN_DB key https://mwatelescope.atlassian.net/wiki/spaces/MP/pages/24969594/Metafits+files

andreww5au commented 3 months ago

ATTEN_DB is an integer attenuation offset applied to the observation as a whole, by the ASC unit inside each receiver before digitising. For almost every observation, it is equal to 1, but for almost all Solar observations, it's equal to 9, to prevent clipping if the Sun is very bright. Occasionally (eg, RFI scans) higher values have been used. Negative values (down to -6 or so) are possible. If a calibration solution taken with one ATTEN_DB value is applied to an observation taken with a different ATTEN_DB value, gain solutions should be corrected for the difference.