# The LWA-SV Orville Image Archive

Updated: 2026/4/8

## Description
This archive contains images generated by the Orville Wideband Imager running at
LWA-SV.  Orville is a Bifrost-based GPU imager for the wideband correlator output
from the Next Generation Digital Processor at Sevilleta.  It generates images in
real-time and generates images in all four Stokes parameters on a five second
cadence.  The system has been operational since May of 2020.  These images are
also used as the basis for LWA TV2 which can be seen at: http://www.phys.unm.edu/~lwa/lwatv2.html

## Archive Organization and Naming
The files in the archive are grouped into directories by the Modified Julian Date
(MJD) of the observation.  Inside each of these directories are one or more
Orville `.oims` image files.  The files are named using a combination of the:
	* MJD, 
	* UTC hour of the observation
	* the lowest frequency in the band in MHz, and
	* the highest frequency in the band in MHz.

## Indexing and Searching
A searchable index of the image data available at https://lda10g.alliance.unm.edu/explore/orville/orville_db
This database contains Orville images from all LWA stations that contribute data
to this archive.

## Image Access
The images generated by Orville are stored in binary `.oims` format that contains
one or more integrations.  These images can be read in Python using the `OrvilleImageDB.py`
module that can be found at: https://github.com/lwa-project/orville_wideband_imager

## Quality Metrics
Starting in early 2026 the `.oims` files contain per-integration and per-frequency
channel quality metric generated by the [Oarfish classifier](https://github.com/lwa-project/oarfish).
These metrics are stored in the integration headers under the `extended-attributes`
field and contain a numeric ranking (0-1, higher is better) and a text label
(corrupted, low-rfi, good, etc.).  See the Oarfish page for details of the
classification method.

## Astrometry and Flux Calibration
The data are provided with basic astrometry but are otherwise uncalibrated.  For
the most recent procedures for improve the astrometry and setting the flux scale
see "Reassessing the Relationship between Meteor Radio Afterglows and Optical
Persistent Trains" (2025 JGR Space Physics, 130, e2025JA034327).

## References and Acknowledgement
If you make use of the data contained in this archive please reference the
following papers:

Orville Description
  Varghese, S.S., Dowell, J., Obenberger, K.S., Taylor, G.B., & Malins, J.
  2021, JGR Space Physics, e2021JA029296  "Broadband Imaging to Study the
  Spectral Distribution of Meteor Radio Afterglows"
	
  Dowell, J., Varghese, S., & Taylor, G. B. LWA Memo \#215  "The Orville
  Wideband Imager" (Sep 9, 2020.)
	
LWA-SV Station Description
  Cranmer, M.D. et al. 2017, JAI, 650007  "Bifrost: a Python/C++ Framework for
  High-Throughput Stream Processing in Astronomy"
	
You should also include the following line in the acknowledgements:
> Construction of the LWA has been supported by the Office of Naval Research 
> under Contract N00014-07-C-0147 and by the AFOSR. Support for operations 
> and continuing development of the LWA1 is provided by the Air Force 
> Research Laboratory and the National Science Foundation under grants 
> AST-1835400 and AGS1708855.

## Contact Information
For questions about the LWA-SV Orville Image Archive send e-mail to: lwa (at) unm.edu.