Anyone doing hydrogen line observing?

[Victor Boesen]

9 hours ago, Carl Reade said:

Yes there are three peaks in there here's what I got a while back. Working well!!

 

Great looking spectrum! Thanks for confirming my own observation;)

[Ed astro]

On 02/01/2021 at 17:46, Victor Boesen said:

Thanks to @Ed astro for the simple solution of just collecting an "empty" sample at a slightly higher or lower frequency I had some time today to brush up my software. I think it turned out nice, but I have some issues to fix when averaging a large number of FFT's and the y-axis which doesn't really contain any useful information as of now.

Here are two images of the hydrogen line between Cygnus and Cassiopeia and one in from around Deneb in Cygnus. I believe I managed to catch two peaks in the first photo(maybe even three but the resolution isn't high enough to confirm I'd say).

Thanks all!

Victor

Hi Victor,

Nice spectra! 

If you want to check your hydrogen line measurements you can use the LAB survey HI profile search: https://www.astro.uni-bonn.de/hisurvey/euhou/LABprofile/index.php. You can fill in the galactic longitude and latitude of the spot in the sky you were observing, and the beamsize of the antenna in degrees (if you are using a dish, this is approximately 70 X wavelength / dish diameter.)

Best regards,

Eduard

 

[Victor Boesen]

I've been working some more on my H-line software/project and managed to properly calculate signal to noise ratio and current equatorial coordinates of the telescope. My next goal will most likely be to add another x-axis on the top to display relative velocity, and then figure out a way to map the hydrogen intensity & doppler in the milky way.
https://github.com/byggemandboesen/H-line-software

I really like the double (almost triple) peak in Cassiopeia as seen above! The following image is from Meissa in the head of Orion. I'm impressed with the "spike"-like structure of it compared to the "hump" otherwise seen in Cygnus and Cassiopeia. The doppler is also quite impressive.

Finally Mirach in Andromeda where the signal is noticeably weaker than in the other areas of the Milky way.

And here's a quick image with my phone and the dish pointed at Mirach with a passing satellite (The brightest "star")

Thanks for the help from here!

Victor

[Carl Reade]

Excellent results! Keep posting👏

[Victor Boesen]

It's been a while since I've posted here, so I thought I'd return with an update:) I've done more work on my hydrogen line software which includes better signal-to-noise ratio estimates, better doppler calculation, removing interference spikes from observations and I've begun calculating absolute velocity from the relative velocity observed in the doppler shift (still work in progress).

https://github.com/byggemandboesen/H-line-software

Today I did a sweep across the galactic plane and stitched the frames together in a short GIF. I'm pretty happy with how my software is coming along, and the results have improved quite a lot despite using the same equipment.

The sweep is 10 degree steps from 85 degrees galactic longitude to -165 degrees (or 195 depends on how you put it).
My main objective right now is to tidy things up in my code and fix the "obj. velocity" calculations. Not that it's wrong right now, it's just showing the objects velocity in the direction observed instead of the rotational direction around the Milky way. The setup remains the same, and here's an image of everything set up on a Manfrotto photo tripod and an AZ4 telescope mount head.

Thanks for looking!

Victor

[Victor Boesen]

Time has once again passed like it usually does, but in the meanwhile I've slowly, time permitting, continued working on my hydrogen line observations. I've managed a total of 19 observations along the galactic plane in 10 degree intervals ranging from 15 degrees to 195 degrees. The following photo is a composition of all the observations and their corresponding galactic longitude.

Furthermore, I've been able to approximate the rotation curve/orbital velocity of the Milky way from 6 observations in the interval of 25 degrees to 75 degrees using the tangent method. Considering the dish size and equipment used this is more than I could've ever asked for when I began writing my own software to do hydrogen line astronomy.

The chart above shows my project's results (blue) and the corrected results which account for the orbital speed of the Earth around the Sun (red). I'm fortunate enough to actually write about my project in a national danish science competition in which I'm through to the finale and just handed in my final article and findings. I never expected this but hope to do my best in the finale.

The code is still being updated when I have the time:
https://github.com/byggemandboesen/H-line-software

As always, thanks for looking!

Victor

Edited April 11, 2021 by Victor Boesen

[Victor Boesen]

Hi everyone, yesterday I performed an observation again in the Cygnus area with the same setup as my previous observations. I've made a couple changes to my software including a small map displaying the obseved area in the Milky Way and some detail about the observation.

Here's a link to my software, if anyone is interested in trying it out. It works for regular RTL units.

Thanks for looking!

Victor