---
name: "mDAG"
section: "1"
platform: "linux"
package: "montage-gridtools"
version: "6.1+dfsg-1+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/mDAG"
---

# mDAG(1)

Create a Directed Acyclic Graph (DAG) for Pegasus

## NAME

mDAG - Create a Directed Acyclic Graph (DAG) for Pegasus

## SYNOPSIS

mDAG survey band objstr width height cdelt workdir workurlbase \[urlbase\]

mDAG -h survey band hdrfile workdir workurlbase \[urlbase\]

## DESCRIPTION

mDAG creates an XML-based Directed Acyclic Graph (DAG) that specifies  "jobs" or Montage modules to be run to produce a mosaic,  "files" to be consumed or generated during processing (input, intermediate, and output files), and "dependencies" between jobs and files that imply an order in which jobs should be run.  In this "abstract graph", logical names are assigned to jobs and files.  The abstract graph is intended to be an input to a job scheduler, such as Pegasus in the Chimera Virtual Data System.

## OPTIONS

- \-h

  Output mosaic is based on a header file rather than explicit object name (for location), sizes and scale.

## ARGUMENTS

- survey

  mDAG has custom code for dealing with surveys (*e.g.* DSS) where we know we have to use the slower mProject module rather than mProjectPP.

- band

  mDAG also has custom code for the 2MASS survey where Montage scales the data to a project-specified magnitude zero point by band (J,H,K).

- objstr

  Object name, resolved through NED/SIMBAD for sky location.

- width/height

  Size of the image in degrees.

- cdelt

  Pixel scale in degrees.

- hdrfile

  Instead of objstr, width, height, and cdelt the user an provide a pre-built FITS header.

- workdir

  There are a collection of files the processing will need ane which mDAG creates. The user needs to create a location for this and give it to mDAG.

- workurlbase

  While working, some files in the workspace are accessed via URL.  Again, this needs to be set up by the user beforehand.

- urlbase

  Optionally, results can be made URL-accessible if this parameter is given.

## RESULT

If successful, the workspace will be populated with severeal tables and with the "dag.xml" file to be given to the workflow manager.

## MESSAGES

- ERROR

  Error opening debug file

- ERROR

  Error opening header template file

- ERROR

  Error opening big header template file

- ERROR

  Error opening image list

- ERROR

  Error opening working file list for write

- ERROR

  Error opening working file list for read

- ERROR

  Error opening parent list

- ERROR

  Error opening sorted parent list

- ERROR

  Bad template: *file*

- ERROR

  Output wcsinit() failed.

- ERROR

  *general error message*

- ERROR

  No return message from object lookup.

- ERROR

  Invalid location specification or object name.

- ERROR

  Can't find RA in lookup return.

- ERROR

  Can't find Dec in lookup return.

- ERROR

  Couldn't find host *hostname*

- ERROR

  Couldn't create socket()

- ERROR, msg=

  *hostname*: connect failed.

## EXAMPLES

- mDAG 2mass j m51 0.5 0.5 0.00277778 m51work http://montage-web.ipac.caltech.edu/workspace/m51

  \[struct stat="OK", id="20150904\_095958\_21631"\]

## BUGS

The drizzle algorithm has been implemented but has not been tested in this release.

If a header template contains carriage returns (i.e., created/modified on a Windows machine), the cfitsio library will be unable to read it properly, resulting in the error: \[struct stat="ERROR", status=207, msg="illegal character in keyword"\]

It is best for the background correction algorithms if the area described in the header template completely encloses all of the input images in their entirety. If parts of input images are "chopped off" by the header template, the background correction will be affected. We recommend you use an expanded header for the reprojection and background modeling steps, returning to the originally desired header size for the final coaddition. The default background matching assumes that there are no non-linear background variations in the individual images (and therefore in the overlap differences). If there is any uncertainty in this regard, it is safer to turn on the "level only" background matching (the "-l" flag in mBgModel.

## COPYRIGHT

2001-2015 California Institute of Technology, Pasadena, California

If your research uses Montage, please include the following acknowledgement: "This research made use of Montage. It is funded by the National Science Foundation under Grant Number ACI-1440620, and was previously funded by the National Aeronautics and Space Administration's Earth Science Technology Office, Computation Technologies Project, under Cooperative Agreement Number NCC5-626 between NASA and the California Institute of Technology."

The Montage distribution includes an adaptation of the MOPEX algorithm developed at the Spitzer Science Center.