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Sarah Jamie Lewis
+ Your AuthorsArchive @SarahJamieLewis Executive Director @OpenPriv. Cryptography and Privacy Researcher. @cwtch_im icyt7rvdsdci42h6si2ibtwucdmjrlcb2ezkecuagtquiiflbkxf2cqd Jun. 04, 2021 1 min read

Over the last few weeks I've been slowly (re)building my radio telescope, and today I managed to get it out for a few hours and it works!

Still in need of some proper calibration, and some tuning - but here is a ridiculously tiny slice of the galaxy as seen via neutral hydrogen.

Time goes left to right, from the galactic pane roughly at zenith on the left, to an "empty" sky on the right (total time just under 6 hours)

Frequency is labelled. 21cm line is aligned with the grid running through the observation.

For those who may not know - the reason that the observed signal spreads out beyond just the radiation frequency of 1420.40Mhz is because different arms of our galaxy are moving towards us/away from us and us such the signal is blueshifted/redshifted!

The telescope points straight up (at zenith) and so the signal changes as the galactic plane moved overhead.

In terms of future work: As summer progresses I want to try and do a full 24-hour observation.

I have a new LNA coming soon to replace my current one, and I need to experiment with some external filters and radio settings to minimize noise.

It's been 2 years since I built my first version of the antenna and managed to get a single decent observation.

Here is a reverse-video from last observation to first (I started observing when the galactic plane was just past zenith so the signal was already strong - playing it in reverse means you can watch the signal grow)

Weather isn't great this weekend so I've been working on the data processing / visualization pipeline part of my radio telescope.

Here is the observation from Thursday nicely laid on an RA/Dec grid (with a star map backing for context)

I (roughly) blended the redshift and blueshifted components of the signal which results in a very purple line where galactic plane intersects, then a slight red shift, and then a slow fade in intensity as the antenna points to cold space late on.

You can follow @SarahJamieLewis.


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