[daip] Question about using AIPS for radio image synthesis {External} {External} {External} {External}

Tue Jul 25 22:41:55 EDT 2023

Dear Eric Greisen,

Thank you very much for you suggestion.

Yours sincerely,

Jedsada Maklai

Research Assistant (by Dr. Ram Kesh Yadav)

National Astronomical Research Institute of Thailand (NARIT)

________________________________
From: Eric Greisen <egreisen at nrao.edu>
Sent: Tuesday, July 25, 2023 10:10:01 PM
To: Jedsada Maklai
Cc: daip at nrao.edu
Subject: Re: [daip] Question about using AIPS for radio image synthesis {External} {External} {External}

Step 6 suggests that you run FRING on a single scan and apply that to all
the data.  Take the stronger cal source and 1 scan.

Steps 7 and 8 allow you to do the SETJY and BPASS with both sources.  Two
primary calibrators should work as well as having multiple scans on one.

> Dear Eric Greisen,
>
>
> Thank you very much for your previous suggestions again. I would like to
> ask another question.
>
>
> As per your suggestions, I am following chap. 4 of the AIPS cookbook for
> the calibration. In the section 4.3 (Beginning the calibration), the steps
> 6-8 seem to be applied for only one primary flux calibrator. However, my
> data consists of 2 primary flux calibrators observed at the beginning and
> at the end of the observations. My question is, how should I include both
> the calibrators as per the cookbook's instructions especially in that
> specific part?
>
>
> Thank you very much in advance.
>
>
> Yours sincerely,
>
> Jedsada Maklai
>
> ________________________________
> From: Jedsada Maklai
> Sent: Wednesday, July 19, 2023 3:43:58 PM
> To: egreisen at nrao.edu
> Subject: Re: [daip] Question about using AIPS for radio image synthesis
> {External} {External}
>
>
> Dear Eric Greisen,
>
>
> In fact, I have studied the AIPS cookbook for a while. However, I don't
> have any idea of how to calibrate GMRT data.
>
>
> So, for GMRT data reduction. Is it alright to use the methods suggested
> for VLBI data calibration (at section 9.1 of the cookbook)?
>
>
> I have already loaded the data using FITLD and INDXR. After that, I
> examine the data with several task suggested in step 2 in that section (in
> which I think that the data looks alright in my sense, which I don't know
> is my sense coherent with AIPS specialists or not)
>
>
> For step 3, I found problem because GMRT didn't provide any calibration
> file. So I skip this step. I quite not sure is it alright or not.
>
>
> For step 6 (edit the data), the things that I have to flag is RFI, right?
> Now I quite confuse. I don't know which task is suitable for flagging RFI.
> My idea is using task POSSM to plot cross-correlation of every antenna
> pair in both RR and LL polarization and then note down the channels which
> possibly be RFI in each antenna pair and polarization and then using task
> UVFLG to flag them. The problem is, there are ~30 antennae, 2 pols, 2048
> channels which quite a lot. So could you mind suggest me the effective
> method for flagging RFI?
>
>
> Could you mind suggest me, please? Sorry, it's quite a bit long.
>
>
> Yours sincerely,
>
> Jedsada Maklai
>
> Research Assistant (by Dr. Ram Kesh Yadav)
> National Astronomical Research Institute of Thailand (NARIT)
>
>
> ________________________________
> From: Jedsada Maklai
> Sent: Wednesday, July 19, 2023 8:54:37 AM
> To: egreisen at nrao.edu
> Subject: Re: [daip] Question about using AIPS for radio image synthesis
> {External} {External}
>
>
> Dear Eric Greisen,
>
>
> Thank you very much for your suggestion.
>
>
> Yours sincerely,
>
> Jedsada Maklai
>
> Research Assistant (by Dr. Ram Kesh Yadav)
>
> National Astronomical Research Institute of Thailand (NARIT)
>
> ________________________________
> From: Eric Greisen <egreisen at nrao.edu>
> Sent: Tuesday, July 18, 2023 10:09:48 PM
> To: Jedsada Maklai
> Subject: Re: [daip] Question about using AIPS for radio image synthesis
> {External} {External}
>
> Let me recommend the AIPS CookBook which is available in your installation
> at $AIPS_ROOT/TEXT/PUBL in chapters named COOK?.PS where ? =
> 1,2,3,...13,A,B,C... or as COOKBOOK.PDF.  The Workshop you mention will
> concentrate on CASA rather than AIPS.
>
> Eric Greisen
>
>> Dear Eric Greisen,
>>
>>
>> Thank you very much for your suggestion. Using AIPS software is really
>> challenge for me. I never have any chance to have in-person training or
>> workshop before, and the best thing I can do is consulting with some
>> specialists remotely. If I have more chance to continue my job in this
>> area, I will try to attend to NRAO data reduction workshop which will be
>> held next year so my skill in this software will be improved.
>>
>>
>> Yours sincerely,
>>
>> Jedsada Maklai
>>
>> Research Assistant (by Dr. Ram Kaesh Yadav)
>>
>> National Astronomical Research Institute of Thailand (NARIT)
>>
>> ________________________________
>> From: Eric Greisen <egreisen at nrao.edu>
>> Sent: Monday, July 17, 2023 10:58:11 PM
>> To: Jedsada Maklai
>> Cc: daip at nrao.edu; Ram Kesh Yadav
>> Subject: Re: [daip] Question about using AIPS for radio image synthesis
>> {External}
>>
>> CLINT is the interval between values in the CL table.  If the
>> calibration
>> varies rapidly with time, then it should be shorter than 1 minute.  At
>> your
>> frequency, the default or 1.05 should be fine.  The reason to use QUACK
>> is
>> that on some systems the first first data record or two or three are
>> affected by scan startup issues and have incorrect amplitude or phase
>> compared to the rest.  Do not use QUACK until you have examined
>> calibrator
>> source data in detail to see if there are issues at the start and end of
>> scans.  That examination will show you what values to use for QUACK if
>> any.
>>
>> Eric Greisen
>>
>>
>>> Dear NRAO staffs,
>>>
>>>
>>> Now I am doing task QUACK. However, I don't know what the values of
>>> APARM
>>> in it should be. I will do the cutting at the beginning of each scan,
>>> is
>>> it enough? Or should I do the cutting at the end of each scan also? The
>>> attached file shows the scan data which I retrieve from task LISTR.
>>>
>>>
>>> Could you mind explain how to do the decision about it also, please?
>>>
>>>
>>> Yours sincerely,
>>>
>>> Jedsada Maklai
>>>
>>> Research Assistant (by Dr. Ram Kesh Yadav)
>>>
>>> National Astronomical Research Institute of Thailand (NARIT)
>>>
>>>
>>> ________________________________
>>> From: Jedsada Maklai
>>> Sent: Monday, July 17, 2023 10:20:01 AM
>>> To: daip at nrao.edu
>>> Cc: Ram Kesh Yadav
>>> Subject: Question about using AIPS for radio image synthesis
>>>
>>>
>>> Dear NRAO staffs,
>>>
>>>
>>> I'm using AIPS in order to do the image synthesis. It is radio
>>> continuum
>>> data from GMRT observation at 1260 MHz.
>>>
>>>
>>> The question is, in task FITLD, what is the suitable value for CLINT
>>> parameter? and why? What is the criteria for justifying the suitable
>>> value
>>> of CLINT in general?
>>>
>>>
>>> (Someone used to suggest me that the suitable value should be 1.05 but
>>> I
>>> don't know the reason. My professor said I should know the reason
>>> behind
>>> this also so I will be able to apply it to other observations in the
>>> future.)
>>>
>>>
>>> So, could you mind explain it to me, please?
>>>
>>>
>>> Yours sincerely,
>>>
>>> Jedsada Maklai
>>>
>>> Research Assistant (by Dr. Ram Kesh Yadav)
>>>
>>> National Astronomical Research Institute of Thailand (NARIT)
>>> _______________________________________________
>>> Daip mailing list
>>> Daip at listmgr.nrao.edu
>>> https://listmgr.nrao.edu/mailman/listinfo/daip
>>>
>>
>>
>> Eric W Greisen
>>
>>
>>
>
>
> Eric W Greisen
>
>
>

Eric W Greisen

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20230726/c8dc0739/attachment-0001.html>