Daily Image
08-01-2014
Observation of HI absorption line by APERTIF UniBoard
| Submitter: | Boudewijn Hut for the APERTIF team |
| Description: | We proudly present the first observation of an HI absorption line detected by the APERTIF system with a UniBoard backend! The (nearly) final APERTIF hardware, as it was used to do the first APERTIF UniBoard pulsar detection a few weeks ago, has now also been used to observe this spectral line feature of the bright radio source 3C84 (NGC 1275). 3C84 is a strong radio continuum source, but a cloud of HI gas in between the source and the telescope absorbs the emission from 3C 84 in a narrow band. This shows up in the measured data as an absorption line at 1382.97 MHz. The 2 MHz frequency band shown here is a combination of three sub-bands, each 0.78125 MHz wide. The sub-band filter responses were removed from the data by means position switching, in which the observation is done twice, i.e. on-source and off-source. The total observation time is ~9 hours. The figure represents the ratio of both measurements, and shows no sub-band filter responses at all - resulting in this nice spectrum of 3C84! |
| Copyright: | ASTRON, 2013. |
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