What are the website's features?

Here is a video describing the website's features:



How do I generate my own data?

Here is a video tutorial explaining how to generate your own data using our web forum:



What are the data formats and how do I use them?

We use OIFITS, MAT, and ASCII data formats. We describe OIFITS and MAT below in detail.

OIFITS

The primary data format that we have chosen to use is OIFITS. OIFITS is a standard for exchanging data for Optical (Visible/IR) Interferometry, and is based on the FITS Standard. Since mm/sub-mm VLBI shares a lot of similarities to optical interferometry, this format is better suited for mm/sub-mm measurements than UVFITS. More information on the OIFITS format can be found here. We list the variables described in this paper in the tables below.

We provide a number of tools that may be useful in reading and writting in the OIFITS format:

  • Paul Boley has written a OIFITS Python module that you can download here
  • Python code that can be used to write an OIFITS file from an output MAPS text file can be downloaded here
  • Python code by Andrew Chael to extract information from OIFITS and write it to a text file can be downloaded here
OI_T3 Variables Description Units
T3AMP Triple-product/Bispectrum amplitude Jansky3
T3PHI Triple-product phase Degrees
T3AMPERR Standard deviation of error in triple product amplitude Jansky3
T3PHIERR Standard deviation of error in phase Degrees
U1COORD u coordinate of baseline AB of the triangle meters
U2COORD u coordinate of baseline BC of the triangle meters
V1COORD v coordinate of baseline AB of the triangle meters
V2COORD v coordinate of baseline BC of the triangle meters
STA_INDEX Station numbers contributing to the data
INT_TIME Integration time seconds
MJD Modified Julian Date
TIME UTC time of observation seconds
OI_VIS2 Variables Description Units
VIS2DATA Squared visibility Jansky2
VIS2ERR Standard deviation of error in squared visibility Jansky2
UCOORD u coordinate of baseline meters
VCOORD v coordinate of baseline meters
STA_INDEX Station numbers contributing to the data
INT_TIME Integration time seconds
MJD Modified Julian Date
TIME UTC time of observation seconds
OI_VIS Variables Description Units
VISAMP Squared visibility Jansky
VISPHI Visibility phase Degrees
VIS2ERR Standard deviation of error in squared visibility Jansky
VISPHIERR Error in visibility phase in degrees Degrees
UCOORD u coordinate of baseline meters
VCOORD v coordinate of baseline meters
STA_INDEX Station numbers contributing to the data
INT_TIME Integration time seconds
MJD Modified Julian Date
TIME UTC time of observation seconds
OI_WAVELENGTH Variables Description Units
EFF_WAVE Effective wavelength of channel meters
EFF_BAND Effective bandpass of channel meters
OI_ARRAY Variables Description Units
TEL_NAME/STA_NAME Station name
STA_INDEX Station number
DIAMETER Element diameter meters


MAT

We have also included the data in MATLAB's MAT-file format. The MAT-file stores workspace variables that can be easily loaded into MATLAB or Octave. Due to the ease of loading and viewing the data in the MAT format, this can be helpful for verifying that you are reading the OIFITS data correctly.

Bispectrum Variables Description Units
t3amp Triple-product/Bispectrum amplitude Jansky3
t3phi Triple-product phase Degrees
t3amperr Standard deviation of error in triple product amplitude Jansky3
t3phierr Standard deviation of error in phase Degrees
uClosure u coordinate of baseline AB of the triangle wavelengths
vClosure v coordinate of baseline AB of the triangle wavelengths
antOrder Station numbers contributing to the data
mjdClosure Modified Julian Date
Visiility Variables Description Units
amp Triple-product/Bispectrum amplitude Jansky
phase Triple-product phase Degrees
viserror Standard deviation of error in triple product amplitude Jansky
u u coordinate of baseline wavelengths
v v coordinate of baseline wavelengths
ant1 Station number 1 contributing to the data
ant2 Station number 2 contributing to the data
mjd Modified Julian Date
Miscellaneous Variables Description Units
frequency Effective frequency of channel Hertz
bandWidth Effective bandwidth of channel Hertz
intTime Integration time seconds
RACent Right Ascension Degrees
DECCent Declination Degrees


Why does the data generation forum produce an error when I submit?

Since we are still in the development phase, there are a number of reasons that this may happen. A common reason is that the web application is not supported by the browser you are using. For the time being, please use Chrome or Firefox to generate your data from our web forum. If this does not fix your problem, please contact us at vlbiimaging@gmail.com.

Who should I contact if I have questions?

Please email vlbiimaging@gmail.com with any questions.