UVPLT shows interesting image!

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Mandy
Posts: 14
Joined: Fri Oct 08, 2010 3:11 am

Re: UVPLT shows interesting image!

Post by Mandy »

The two plots are below with appropriate scales for the data range in each case:

uvspec vis=1934-638.1750 select="ant(1)" stokes=xx,yy interval=15 axis=freq,phase yrange=-05,05 device=/xwindow nxy=5,6
1934-638_1750phase.jpg
1934-638_1750phase.jpg (16.68 KiB) Viewed 81295 times
uvspec vis=1934-638.1750 select="ant(1)" stokes=xx,yy interval=15 axis=freq,amplitude yrange=8,22 device=/xwindow nxy=5,6
19334-638_1750ampl.jpg
19334-638_1750ampl.jpg (17.32 KiB) Viewed 81296 times
Doesn't look so great now :( Thanks in advance

Mandy
Mandy
Posts: 14
Joined: Fri Oct 08, 2010 3:11 am

Re: UVPLT shows interesting image!

Post by Mandy »

HI Emil

Don't suppose you have idea's on these latest plots do you? I'm currently going back over all the steps to see if I can see where I've gone wrong.

Cheers

Mandy
ste616
Site Admin
Posts: 220
Joined: Thu Feb 04, 2010 3:27 pm
Location: Paul Wild Observatory Narrabri NSW

Re: UVPLT shows interesting image!

Post by ste616 »

Hi Mandy,

You've averaged these plots over 15 minutes, which means that there could be some bad data mixed in with good data here. My quickest assumption would be that there is some data remaining from when you set up the array with 1934-638, and that data will be at the earliest times. My suggestion would be to plot time vs amplitude and time vs phase in uvplt (with no time averaging, and options=nofqav) and post them here.
cheers
Jamie Stevens
ATCA Senior System Scientist
Mandy
Posts: 14
Joined: Fri Oct 08, 2010 3:11 am

Re: UVPLT shows interesting image!

Post by Mandy »

Thanks Jamie

I tried the following but got the message "Unrecognised option nofqav"

miriad% uvspec vis=1934-638.1750 select="ant(1)" stokes=xx,yy options=nofqav axis=time,amplitude yrange=8,22 device=/xwindow nxy=5,6

I'll continue trying to get this working - it'll be something simple I expect but if you have any advice I'd appreciate it.

Thanks

Mandy
ste616
Site Admin
Posts: 220
Joined: Thu Feb 04, 2010 3:27 pm
Location: Paul Wild Observatory Narrabri NSW

Re: UVPLT shows interesting image!

Post by ste616 »

Hi Mandy,

Sorry, I meant make the axis=time,amplitude and axis=time,phase plots in the 'uvplt' task, which understands the nofqav option, not uvspec.

cheers
Jamie
cheers
Jamie Stevens
ATCA Senior System Scientist
len067
ATCA Expert
Posts: 66
Joined: Mon Feb 08, 2010 2:35 pm

Re: UVPLT shows interesting image!

Post by len067 »

Hi Mandy,

Perhaps use uvplt instead of uvspec (I don't think that uvspec allows you to specify "time" as an axis ... but I could be wrong).

Cheers,

Emil.
len067
ATCA Expert
Posts: 66
Joined: Mon Feb 08, 2010 2:35 pm

Re: UVPLT shows interesting image!

Post by len067 »

Argh! Jamie beat me to it by one minute! ;-)

Sorry for the duplication.
Mandy
Posts: 14
Joined: Fri Oct 08, 2010 3:11 am

Re: UVPLT shows interesting image!

Post by Mandy »

No Problem - the more the merrier - thanks Guys. I will try all options

I did carry on with the reduction process to see if I could get an image out - which I did :-) It very obviously needs improving but at least I have sorted out the main steps in the whole process and learning lots along the way.

Will post again soon - thanks for your help

Mandy
Mandy
Posts: 14
Joined: Fri Oct 08, 2010 3:11 am

Re: UVPLT shows interesting image!

Post by Mandy »

Hi Jamie/Emile

OK I've done as you suggested and plotted time v amplitude and time v phase - these are the plots. I hope they mean something to you because they don't to me :cry

uvplt vis=1934-638.1750 select="ant(1)" stokes=xx,yy options=nofqav axis=amplitude,time xrange=8,22 device=/xwindow nxy=5,6
uvplt_tvamp.gif
uvplt_tvamp.gif (4.4 KiB) Viewed 81284 times
uvplt vis=1934-638.1750 select="ant(1)" stokes=xx,yy options=nofqav axis=phase,time xrange=8,22 device=/xwindow nxy=5,6
uvplt_tvpha.gif
uvplt_tvpha.gif (6.2 KiB) Viewed 81284 times
Any thoughts on this?

Cheers

Mandy
ste616
Site Admin
Posts: 220
Joined: Thu Feb 04, 2010 3:27 pm
Location: Paul Wild Observatory Narrabri NSW

Re: UVPLT shows interesting image!

Post by ste616 »

Hi Mandy,

The phase diagrams show me that you still have some phase errors. If you have ran this dataset through mfcal or gpcal, the resultant phase v time plot in uvplot (and usually we plot the axes the other way around, with time on the x-axis) should show a collection of points tightly clustered around 0 degrees. It is difficult to tell whether there is some setup data here that you haven't flagged (relaxing your xrange restriction might make it clearer), but this dataset definitely needs some more flagging. Given that you are in the 20cm band, I wouldn't be surprised if there is still some rather strong RFI here. I suggest taking a look at this dataset in pgflag - it might make it clearer where the intereference is.
cheers
Jamie Stevens
ATCA Senior System Scientist
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