[Difx-users] Question - correlate near field sources ie Spacecraft

Thu Feb 27 19:28:24 EST 2020

Hi Adam,

I tried that { yes I have the skills to hack VEX files (had to do it at the weekend for a EVN observsation)}

I got a different error.

Stuart Weston

Mobile: 021 713062

Skype: stuart.d.weston
Email:  stuart.weston at aut.ac.nz

http://www.atnf.csiro.au/people/Stuart.Weston/index.html

Software Engineer
Institute for Radio Astronomy & Space Research (IRASR)
School of Engineering, Computer and Mathematical Sciences
Faculty of Design and Creative Technologies
Auckland University of Technology, New Zealand.

http://www.irasr.aut.ac.nz/

From: Adam Deller <adeller at astro.swin.edu.au>
Sent: Friday, 28 February 2020 12:58 PM
To: Stuart Weston <stuart.weston at aut.ac.nz>
Cc: difx-users at listmgr.nrao.edu
Subject: Re: [Difx-users] Question - correlate near field sources ie Spacecraft

Hi Stuart,

I think if the vex file is wrong (it says Mark5B for a couple of stations when they were actually VDIF) you might need to actually update the vex file.  Can you do that, or is that a bit beyond your vex hacking skills?

Cheers,
Adam

On Fri, 28 Feb 2020 at 10:26, Stuart Weston via Difx-users <difx-users at listmgr.nrao.edu<mailto:difx-users at listmgr.nrao.edu>> wrote:
>> Which in v2d would translate to "format=VDIFL/8016/2"

So the vex file has MARK5B, but two stations recorded VDIF. Drudg knowing the station setup has put the appropriate commands in the prc file to record VDIF.

Anyway I ran through the setup and tried to run it and “errmon” tells me for these files:

This does not look like a valid Mark5B data.

Fair enough, I see its trying to use “format=Mark8-128-2-2” and it should be “format=VDIF_8000-128-2-2” (if I use m5spec on the vdif files).

So I try the above line in the v2d files "format=VDIFL/8016/2" for the appropriate stations, and now when I run vex2difx I get :

Error: cannot change format to VDIF from any other non-VDIF format (antenna WA) with the .v2d file.  You need to change the .vex file.

Hummm, a bit of a catch 22 here ?

Stuart Weston

Mobile: 021 713062

Skype: stuart.d.weston
Email:  stuart.weston at aut.ac.nz<mailto:stuart.weston at aut.ac.nz>

http://www.atnf.csiro.au/people/Stuart.Weston/index.html

Software Engineer
Institute for Radio Astronomy & Space Research (IRASR)
School of Engineering, Computer and Mathematical Sciences
Faculty of Design and Creative Technologies
Auckland University of Technology, New Zealand.

http://www.irasr.aut.ac.nz/

From: Jan Wagner <jwagner105 at googlemail.com<mailto:jwagner105 at googlemail.com>>
Sent: Thursday, 27 February 2020 11:58 PM
To: Stuart Weston <stuart.weston at aut.ac.nz<mailto:stuart.weston at aut.ac.nz>>
Subject: Re: [Difx-users] Question - correlate near field sources ie Spacecraft

Hi Stuart,

due to the strange VDIF format error you could use DiFX utility "printVDIFheader" to verify what the headers of vygr2_wa_no0108 actually say.

Maybe the "legacy" flag is set ('L' column in printVDIFheader output would be all '1').

In that case the frame header size would then be 16 instead of 32 bytes, and format VDIFL instead of VDIF, with a format string *possibly* of "VDIFL_8000-128-2-2". Which in v2d would translate to "format=VDIFL/8016/2".

And as Simone already pointed out, "vsum -s <vdif files>" could be a more convenient way of generating a file list for a set of VDIF files. Vsum autodetects the nasty details of the VDIF format.

Good luck!

Jan

Am 27.02.2020 um 04:05 schrieb Stuart Weston via Difx-users:
Well two of you asked for updates �� Progress so far …

directory2filelist:

First issue, directory2filelist doesn’t like VDIF files (Which I have for Wa and Ti) :

oper at ww-flexbuf-01 DiFX-2.5.2 vygr2> directory2filelist /raid0/etransfer/wa/vygr2_wa_no0108 VDIF_8000-128-2-2
VDIF Warning: Changing frameheadersize from 32 to 16
VDIF Warning: Changing databytesperpacket from 8000 to 124473216
Segmentation fault

It is even more unhappy with “vbs_fs” for merging jive5ab vdif chunks into one logical file at the fuse mount point (PS: I now use “vbs_fs” for DSPSR with Williem for VDIF Single Dish pulsar data).

v2d :

Also for v2d ephemFile has to be either tle (Two-Line elements) or bsp (which I assume means BaryCenter on 399 Earth, our observing platform). Now NASA HORIZONS doesn’t seem to produce a valid file acceptable to SPICE. So goto NASA NAIF which has some “old” archived bsp files but nothing current.

I was trying to use the HORIZONS ID “Voyager_2” , that didn’t work :

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

Toolkit version: N0066

SPICE(IDCODENOTFOUND) --

The target, 'Voyager_2', is not a recognized name for an ephemeris object. The
cause of this problem may be that you need an updated version of the SPICE
Toolkit. Alternatively you may call SPKEZ directly if you know the SPICE ID
codes for both 'Voyager_2' and '399'

A traceback follows.  The name of the highest level module is first.
spkezr_c --> SPKEZR

Oh, by the way:  The SPICELIB error handling actions are USER-TAILORABLE.  You
can choose whether the Toolkit aborts or continues when errors occur, which
error messages to output, and where to send the output.  Please read the ERROR
"Required Reading" file, or see the routines ERRACT, ERRDEV, and ERRPRT.

Anyway under the NAIF archive there is a “voyager_2.ST+1992_m05208u.merged.bsp” which goes to “2021 JAN05”. Now you need NAIF ID 3 for the Earth Barycenter (our observation platform) and NAIF ID -32 for Voyager 2

SOURCE VGR2 {
ephemObject = -32
ephemFile   = voyager_2.ST+1992_m05208u.merged.bsp
}

Now v2d works, there are some warnings about stop/start times for the vdif files.

oper at ww-flexbuf-01 DiFX-2.5.2 vygr2> vex2difx --force vygr2.v2d
Warning: Filelist file vygr_atca.filelist was a listing with no start/stop times.
Note: Future versions of vex2difx may stop allowing file lists without start/stop times.  Filelists for VDIF and Mark5B files with start/stop times can be generated with "vsum -s" and "m5bsum -s" respectively.  These times allow vex2difx to properly assign data to jobs and is especially important in cases where multiple jobs are generated per project.
Warning: Filelist file vygr_dss.filelist was a listing with no start/stop times.
Warning: Filelist file vygr_wa.filelist was a listing with no start/stop times.
start date: 2020y015d08h00m00s
stop date: 2020y015d12h00m00s
Warning: no clock values for antenna AT .
Warning: no clock values for antenna WA .
Warning: no clock values for antenna TI .
Note: Proceeding even though there were 3 warnings.
Warning: Job vygr2 1: no clock offsets being applied to antenna AT
          Unless this is intentional, your results will suffer!
Warning: Job vygr2 1: no clock offsets being applied to antenna TI
          Unless this is intentional, your results will suffer!
Warning: Job vygr2 1: no clock offsets being applied to antenna WA
          Unless this is intentional, your results will suffer!
Warning: Job vygr2 2: no clock offsets being applied to antenna AT
          Unless this is intentional, your results will suffer!
Warning: Job vygr2 2: no clock offsets being applied to antenna TI
          Unless this is intentional, your results will suffer!
Warning: Job vygr2 2: no clock offsets being applied to antenna WA
          Unless this is intentional, your results will suffer!

2 job(s) created.

I’ll come back to the clock offsets next as I do have those to add, I’ll append a $CLOCK section shortly.

I am just working my way through step by step, where each step will have several iterations to sort things out.

Stuart Weston

Mobile: 021 713062

Skype: stuart.d.weston
Email:  stuart.weston at aut.ac.nz<mailto:stuart.weston at aut.ac.nz>

http://www.atnf.csiro.au/people/Stuart.Weston/index.html

Software Engineer
Institute for Radio Astronomy & Space Research (IRASR)
School of Engineering, Computer and Mathematical Sciences
Faculty of Design and Creative Technologies
Auckland University of Technology, New Zealand.

http://www.irasr.aut.ac.nz/

From: Stuart Weston
Sent: Thursday, 27 February 2020 1:51 PM
To: difx-users at listmgr.nrao.edu<mailto:difx-users at listmgr.nrao.edu>
Cc: Oleg Titov <Oleg.Titov at ga.gov.au><mailto:Oleg.Titov at ga.gov.au>
Subject: Question - correlate near field sources ie Spacecraft

I have some VLBI on Voyager to correlate.

So had a read of :

https://www.atnf.csiro.au/vlbi/dokuwiki/doku.php/difx/spacecraft

I have setup SPICE

Anyone done this before and any tip’s, help or suggestions ?

The ephemFile as that as obtained say from https://ssd.jpl.nasa.gov/horizons.cgi ?

Stuart Weston

Mobile: 021 713062

Skype: stuart.d.weston
Email:  stuart.weston at aut.ac.nz<mailto:stuart.weston at aut.ac.nz>

http://www.atnf.csiro.au/people/Stuart.Weston/index.html

Software Engineer
Institute for Radio Astronomy & Space Research (IRASR)
School of Engineering, Computer and Mathematical Sciences
Faculty of Design and Creative Technologies
Auckland University of Technology, New Zealand.

http://www.irasr.aut.ac.nz/

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A/Prof. Adam Deller
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