21cm band. Refurbishing the dish with a new Cantenna.

[SteveBz]

Hi ZiHao,

I think I've found one error.  It was the r = r +/- delta_r bit and obviously for QII & QIII there is only one solution which is the r = r + delta_r one.  I still have quite a lot of further non-standard points.  Here's a cleaned up version:

I'm tempted to download the LAB stuff and see what happens if I chart that.

Thanks for your help.

Steve.

 

 

 

 

 

[SteveBz]

So my Python is definitely not working.  Here it is based on the LAB survey:

Some looks right and some looks crazy.

Steve.

[SteveBz]

I feel I've got as far as I can go here.  I've suppressed some of the worst invalid numbers.  So here is my plot with its asymptote at 180 degrees (I don't know what I can really do about that) compared with the same plot for LAB values on the right.

Now I think I'll spend some time thinking about rotation curves.

Thanks for reading this far and thanks @Victor Boesen and @ZiHao for your support and help.

Kind regards

Steve.

[athornett]

I was very excited to find this thread today. I have myself been attempting hydrogen line observations and my work with some success can be seen at http://astronomy.me.uk/category/radio-astronomy/radio-observation-in-hydrogen-line-1420mhz

I am using an old 86 x 86 cm square phased military array that passes the "that looks OK on my patio" test carries out by my wife, whereas a 3m dish, however much I would like one, has been permanently banned!

What amazes me is that I am successfully obtaining hydrogen line traces in spite of living in the middle of Lichfield UK 400m from a major supermarket school hospital and very busy roads.

These new dongle type SNAs and SDRs have revolutionised radio astronomy bringing it within reach of everyone.

One piece of software that I would highly recommend is ezRA suite written in Python by Ted Cline of SARA (Society of Amateur Radio Astonomers in USA). It is amazing free and Ted is so supportive as is whole SARA membership even if you are not a member, as I discovered!

If you look at my website you can see the incredible plots it produces. It will collect analyse plot data, and then place it against galactic background of known sources and Milky Way, and work out Doppler shift and give you a basic interpretation of that shift all for few clicks of the mouse!

Andy

 

[SteveBz]

On 09/10/2023 at 07:21, athornett said:

I was very excited to find this thread today. I have myself been attempting hydrogen line observations and my work with some success can be seen at http://astronomy.me.uk/category/radio-astronomy/radio-observation-in-hydrogen-line-1420mhz

I am using an old 86 x 86 cm square phased military array that passes the "that looks OK on my patio" test carries out by my wife, whereas a 3m dish, however much I would like one, has been permanently banned!

What amazes me is that I am successfully obtaining hydrogen line traces in spite of living in the middle of Lichfield UK 400m from a major supermarket school hospital and very busy roads.

These new dongle type SNAs and SDRs have revolutionised radio astronomy bringing it within reach of everyone.

One piece of software that I would highly recommend is ezRA suite written in Python by Ted Cline of SARA (Society of Amateur Radio Astonomers in USA). It is amazing free and Ted is so supportive as is whole SARA membership even if you are not a member, as I discovered!

If you look at my website you can see the incredible plots it produces. It will collect analyse plot data, and then place it against galactic background of known sources and Milky Way, and work out Doppler shift and give you a basic interpretation of that shift all for few clicks of the mouse!

Andy

 

Your plots are improving. 86 cm is not too bad. I wanted a 3m dish too, but it was just too expensive. 😫 Even the MIT student dish is only 1.8 m.

My 1.3 m dish was a fiver off ebay, which seemed like a deal.

1.22 x 21cm/86cm is about .3 Radians or 17 degrees. That's the resolution of your scan. You can see how @ZiHao has widened his antenna with struts and wire. You could do the same.

Good luck,

Steve.

[athornett]

Thanks for that. Is that still the case as this is array rather than single antenna?

[SteveBz]

5 hours ago, athornett said:

Thanks for that. Is that still the case as this is array rather than single antenna?

I'm pretty sure. What are the dimensions of the individual elements?

I think the rules are, resolution is set by the largest dimension (ie the array), the sensitivity is set by the elements.

If I'm wrong, Im suresomeone will correct me.

Steve.

[athornett]

I am currently on holiday so csnt measure individual elements but they are correct for band 3 military radio in UK which covers 21cm line = I am trying to remember but I think they are around 10-11cm long each, so half the 21cm. These aerials are designed to have good reception throughout the relevant military band.

[athornett]

Each dipole element is 97mm long and they are in 4 x 4 array, designed for band 3 military reception 

[Alpha Adhito]

Wow, what a superb thread. This is a literal gold mine for amateur radio astronomy I'm looking for 😅. Thanks a lot everyone!

[robin_astro]

This was another good thread