Eduardo Amores and colleagues presented a new web-based tool called GALExtin, which can be used to determine the interstellar extinction in the milky way. Their study recently appeared in Arxiv.
In a broad range of astronomical research, estimates of interstellar extinction are essential. Several maps and models have been published of the large scale interstellar extinction in the Galaxy. However, these maps and models have been developed in different programming languages, with different user interfaces and input/output formats, which makes using and comparing results from these maps and models difficult.
Now, Eduardo B. Amôres and colleagues addressed this issue by developing a tool called GALExtin that estimates interstellar extinction based on both 3D models/maps and 2D maps available. The user only needs to provide a list with coordinates (and distance) and to choose a model/map. GALExtin will then provide an output list with extinction estimates. It can be implemented in any other portal or model that requires interstellar extinction estimates.
How it works?
GALExtin works with two layers. The first one is a client that provides a web form to be filled out by the users, e.g. data such as coordinates and distance for the 3D extinction. Alternatively, the user can insert a list of coordinates (Galactic or Equatorial) with distances. It is also necessary to select the coordinate system and the desired model/map.
In the HTML code, the embedded PHP program accesses an SQL table to attribute a number to the process, unique identification for each run of GALExtin, which is also used to assign and manipulate input and output files names.
Once PHP receives a process number and the information passed through HTML, it calls an IDL program that manages the extinction computation. It verifies the number of input lines. Its primary task consists of calling the routines that compute the interstellar extinction for each chosen model/map.
In the final step, the routine returns the extinction estimates to the main program. The output is displayed in the web form if a single direction is given, or written to a file if a file with coordinates was given. For either Galactic or Equatorial coordinates, the values must be given in decimal degrees.
They also validated their tool by comparing the results of GALExtin with the ones obtained with the original software of the models, dustmaps, as well as with the values obtained using the Vizier−CDS in the case of some maps. You can refer their paper to explore these details. They are also planning to include several other excellent extinction maps and models in GALExtin.
Reference: Eduardo B. Amores, Ricardo M. Jesus, Andre Moitinho, Vladan Arsenijevic, Ronaldo S. Levenhagen, Douglas J. Marshall, Leandro O. Kerber, Roseli Kunzel, Rodrigo A. Moura, “GALExtin: An alternative online tool to determine the interstellar extinction in the Milky Way”, Arxiv, pp. 1-12, 2021. https://arxiv.org/abs/2108.00561
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