First Light!

Jeff Dever, December 12, 2005

First Light is a term that refers to the first observation of an astronomy instrument. In this case, no actual "light" was collected, but we were able to aquire data from the software spectrometer connected to the radio telescope. Radio waves, light photons, its all different frequencies of the same thing.

The first observation was done on December 1, 2005. We aquired several datasets, but only one of those will be presented here. The software spectrometer was configured to have a delta t of 8192 time domain points sampled at 15.6MHz. The frequency resolution is 1.9kHz per channel, with 1024 of the channels kept centered on 3.6MHz (no mapping between the final IF and the 1420 RF has yet been made). Integration time was 100ms and data was aquired for 45min pointed Alt=30 AZ=180 starting at about 3:20pm local solar time.

The following files are available for download:

• Plain text meta data file
• Binary raw data file
• Fits file for visulaisation

	This is an offline visualisation of the aquired data. You should notice a slightly higher intensity vertical line at about 3.6MHz. That's the HI line!
	We can look at the spectra of a single datapoint. This is one spectrum from the above time series of spectra. Can you see the HI line in all that noise?
	This is the same spectra, but smoothed with Rectangular-9. You can see a little peak if you know where to look, but it's hard to discern.
	If a little bit of integration time is good, a lot must be better. Let's take all 45mins and average it in time (ignore the continuous line in this plot). Oh ya, now we are talking, the noise is minimized and the HI line shows clearly.