Scope in a Box (upgraded) Data

[Alex P]

This is probably the last data 'till the Fall as the rainy season has kicked in here in Orlando Fla. 

This data is via the standard 1.0m x 0.6m WiFi grid antenna with side panels.  I'm pleased with the improved S/N and resultant signal strength from this modification.

Data in the 2D plots are  12 ea 5 min data sets of 876K averages.

Data in the 3D plot is 100 ea 5 min data sets 876K averages, Dec40 RA16-24 Hrs

Cheers,

Alex

KK4VB

[Alex P]

This is a plot using Matlab .. a 100 sample Drift Scan in  RA 16 to 24 Hrs, Dec 40 degrees.

Color Amplitude is dB above the Background

[Alfred Aburto]

Excellent work!

What is that at 1420.9 MHz and RA 19.8 Hours?

Al

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[Dr. Rich Russel]

Alex,

Try plotting velocity vs galactic longitude (see 1706.10084.pdf (arxiv.org))

Also, if you plot velocity vs range from galactic center - you have the galactic rotation curve and Milky Way Mass

Approach: See journal article:

Milky Way Rotation Rate and Mass Estimation Using HI Measurements, R. Russel, Radio Astronomy, November-December 2018, pp.77-83, radio-astronomy.org.

Great Work!

Rich

[Dr. Rich Russel]

Here is my paper on Velocity vs. Gal Longitude plotting

Profiling the Milky Way Structure by Plotting Neutral Hydrogen onto a Velocity-Galactic Longitude Map, R. Russel, Radio Astronomy Nov-Dec 2019, radio-astronomy.org. 

[b alex pettit jr]

What you are referring is ~ this time slice  ( vert raw linear ampl units )

What it IS ? someone else can answer that ..

I am pleased that this small system can acquire useful data.

Alex

KK4VB

[Alfred Aburto]

Ah, side lobe of antenna response (pattern)?

Al

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[Dr. Rich Russel]

The object is a hydrogen cloud that has a slightly closing relative velocity. (based on frequency being higher than 1420.406 MHz)

You can also use the SIMBAD Astronomical Database to find what objects are at those coordinates. Just realize that the objects are probably not the source of the HI frequency, they just are on the same celestial coordinates.

Go to SIMBAD: SIMBAD: Query by coordinates (unistra.fr)

Enter Celestial coordinates into Coordinate Query: 19 48 00.0 +40 00 0.0   (Note: RA Declination)

Submit query

You get a list of astronomical objects at those celestial coordinates. At this point you can determine if the object could be producing the signal.

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[Alfred Aburto]

Yes, not sidelobe ... something at a different frequency

Al

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[b alex pettit jr]

Hi Dr Russel,

I need to research how to correct the data for Earth orbital/rotation V  to get Galactic Velocity.

There are steep slopes associated with this 'hobby'.

Alex

[b alex pettit jr]

Are these values reasonable ?

	UT time	Right Ascension	Declination	V-Helio	V_LSRK	V_GAL
				-9.991 km/sec	-28.212 km/sec	-161.281 km/sec

 https://www.gb.nrao.edu/cgi-bin/radvelcalc.py?UTDate=2022%2F03%2F28&UTTime=17%3A15%3A00&RA=24%3A15%3A00&DEC=40%3A00%3A00

This gives the velocity in the direction (RA,Dec) from the point of view of the GBT.
Positive means it is receding from us (redshift); negative, it is approaching (blueshift).

V-Helio is the velocity due to the rotation of the Earth and the motion of the Earth in its orbit around the Sun.

V-LSRK is the velocity referenced to the local standard of rest, in addition to the motions of the Earth.

V-GAL is the velocity referenced to the center of the galaxy.

=========================================================

I should thus Subtract this value -161.281 from that data set ?

Over the  8 hour period, the velocity corrections are

-161  -191 -215 -232 - 239 -237 - 227 -208 -181   ??

Thanks,

Alex

===============================================================

[fasleitung3]

Alex,

Hydrogen spectra from our galaxy are usually referenced to the Local Standard of Rest, so you want to use V_LSRK for your correction.

Wolfgang

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[b alex pettit jr]

Hello Wolfgang,

Thank You.

LSR km/sec correction curve for RA16-24 ( 100 samples )

Data converted to Velocity and corrected via the derived LSR equation from that RA16-20 hr time segment

Yes/No/Maybe ?

Not Corrected for LSRK                                                                                            LSRK Corrected

Best Regards,

Alex KK4VB

[fasleitung3]

Hi Alex,

I had a closer look at your plots. A few remarks:

At the location RA 20:00 Dec 40:00 you expect to see a double peak, a stronger one at around 4 km/s and a weaker one at around -78 km/s (blue shifted). This double peak is what one can see in your plot. Looking at the original frequency plot, the second peak is seen at a higher frequency (about 370 kHz higher). This corresponds to -78 km/s (in radio astronomy blue shifted velocities have a negative sign) which is what you expect.

In your velocity plot, however, the difference is some 110 to 120 km/s. So there must be something not correct in your conversion from frequency to velocity.

Best regards,

Wolfgang

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[b alex pettit jr]

Hello Wolfgang,

THANKS for reviewing the data.

Now,  one pk is at (-)8.6 km/sec and the other at (-)85 km/s  :  delV = 76.4 km/s

Close, but not the  4 km/s & - 78 km/s  delV = 82 km/s you stated .

yes, I need to make RedShifts Plus.

Regards,

Alex

[b alex pettit jr]

Got It ...  I forgot to scale the  array shift loop in ( my case ) the velocity increments of 0.619 km/sec

Thanks.

Alex

[Alfred Aburto]

Good work!

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