Data Analysis using ezRA.

[Arjun Shenoy]

Hello.

I am a PG student currently doing my project on radio astronomy. We are doing our project using an antenna similar to a horn antenna, along with Sawtooth+ H1 LNA and SDR called NESDR. 

The data collection was done using ezRA software available in Github. We plotted the (24 hour ) dataset collected on Jan 22 /2024.The plotting was done according to the video mentioned in the following link.

https://youtu.be/dj3_jikH59Y

 The Plot has been attached below. The bump that is shown in the figure is something that we couldn't understand. It is obtained in some place where it wasn't supposed to  be at ( if i am not wrong ). Can anyone help us with this?

Any help would be so appreciated!

Thank you

Arjun.

[Nathaniel Butts]

Hi Arjun,

The two bumps below seem to indicate that you did measure galactic hydrogen, so good job there!

However, it looks like there's either an issue in the 1) pointing of your telescope or 2) input of location variables in when running ezCol.py.  The title of the plot says defaultKS, so I am suspecting #2 is the issue.

When you run ezCol strictly from the command line, you will want to run it with something like the following:

python3 ezCol.py -ezRAObsLat  <your latt> -ezRAObsLon <your long> -ezRAObsAmsl <your elevation> -ezColAzimuth <azimuth> -ezColElevation <angle>

where:

<your latt> is the lattitude of your physical location, in decimal form

<your long> is the longitude of your physical location, in decimal form

<your elevation> is the altitude of your observation above sea level, in meters

<azimuth> is the azimuth you are pointing your telescope at.  Most people use 180, or South.  I find mine with a compas or an iphone from behind the horn.

<angle> is the angle of your scope from the horizon, or from level.  This can be a bit tricky to measure depending on your telescope, but if you are using a horn antenna then an inclinometer of some sort laid on top of your waveguide should give you a good idea.  When I get home from work I'll send some pictures to describe it a bit better.

Thanks,

Nathan Butts

Wannabe Astronomy

Bowling Green, KY

[Arjun Shenoy]

Hi

Thanks for your reply

We had edited the ezCol.py file and had inputed the values of lat, longitude , azimuth ,elivation, etc according to our location before receiving signal. 

Is there any place other than ezCol.py to be inputed with value.?

Thankyou.

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[tedcl...@gmail.com]

Hello Arjun,

Congratulations on your plots !

The ezSky200 plot you posted says "defaultKS" at the top.
The programs think your observatory was near me, in Kansas (KS) in the United States.

I have guessed your location on earth, and created the attached    ezDefaults.txt    file.
Please copy this file into your    ezRA    directory (maybe in     ezRABase\ezRA    ?).
Please edit and correct the     ezDefaults.txt    file.  Enter the correct numbers.

Now the ezRA programs will know your observatory's location on earth.

When you collect new data, the ezCol proram will write your location on earth into the data files.

===> What is your observatory's location on earth ?


To use this old data, please tell the ezCon program your location on earth, like,

      python3  ../ezRA/ezCon.py  data  -ezRAObsLat  9.9  -ezRAObsLon  76.3  -ezRAObsAmsl  10  -ezRAObsName  Arjun

(Here I am guessing your location on earth, please correct the numbers)

Please post your new    ezSky200    plot.


Good luck !

---
Ted Cline
TedClineGit (at) gmail.com

For folks starting to explore radio astronomy,
      ezRA - Easy Radio Astronomy
      Free 1420 MHz Galactic hydrogen data collection and analysis
      https://github.com/tedcline/ezRA
      Windows and Linux

[Nathaniel Butts]

Howdy Arjun,

Yeah, there are more than one location for coordinates/basic info to be inputted, so I'd follow Ted's suggestion and make an ezDefaultsFile.txt .  This will keep everything in one location and makes editing easier.

Thanks,

Nathan Butts

Wannabe Astronomer

Bowling Green, KY

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[Nathaniel Butts]

Howdy Arjun,

Just for reference, attached is my ezDefaults.txt file.

Thanks,

Nathan Butts

Wannabe Astronomy

Bowling Green, KY

[Alex P]

Try Taking 4 minutes of data vs 10 (?) seconds

~ = 720K samples

# H1 observation setup
-ezColCenterFreqAnt 1420.405     #(Signal          Frequency (MHz))
-ezColCenterFreqRef 1422.905     #(Dicke Reference Frequency (MHz))
-ezColBandWidth        2.400     #(Signal          Bandwidth (MHz))
-ezColFreqBinQtyBits   8         #(For  (2^8) 256 freqBinQty frequencies)
-ezColGain  50                   #(Use max gain)
-ezColAntBtwnRef  10             #(number of Ant samples between Ref samples)
#-ezColUsbRelay   11              #(1 SPST HID relay,     driving feedRef ON or OFF)
-ezColIntegQty   31000           #Samples per integration

[Nathaniel Butts]

I substitute longer integration times by performing multiple integrations of shorter duration.  My 31k samples takes 26 seconds on average to perform at 2^8 bins, but I perform scans for a minimum 5 days/elevation, so I'm getting 155k samples total per ra/dec combo.  

Probably should have gone back to 2^10 bins, but I found through my testing, it would add about 53% more time to the survey.  It's already going to take 140 days/meridian assuming no disruptions, so I wasn't really willing to absorb more time; at least not yet.

Thanks,

Nathan Butts

Wannabe Astronomer

Bowling Green, KY

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[b alex pettit jr]

It would be quite useful if you could  compare the  S/N of this  drift-scan ( single 5 minute average data set )

against your 10X shorter ( 30 sec vs 300 sec )  time per average X 5 day technique ..

Dec+40dg  ~  RA20:30  5 min avgs..  one pass 

( no additional  filtering, 'cleaning',  or smoothing,  just baseline drift corrected )

Alex

[Nathaniel Butts]

I'll have to figure out how to plot it.  I'm doing a reference measurement after every 10 integrations.  Is a good thing to check, though.

Thanks,

Nathan Butts

Wannabe Astronomer

Bowling Green, KY

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[b alex pettit jr]

This is a useful method to quantify ( calculate)  S/N in terms of   Pk/RMS

Vert axis : ( relative)  Power  not  dB

[Arjun Shenoy]

Hi everyone

Thankyou for your suggestion and help. It helped very much.

We have started to take reading and plot them.

Walking through the new learning curve

Thankyou everyone for support and help.

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