How to access the Milky Way Project DR2 catalog

Recently the Milky Way Project Data Release 2 was published. You might want to look at the data. This is not as simple as going to the vizieR online catalog and choosing a some coordinates. You need the online catalog, IRSA, an excel sheet and this tutorial.

You can find the paper for the MWP DR2 here: Jayasinghe et al. 2019


First you have to go to the vizieR online catalog and choose some random part of the Milky Way. The coordinates should cover either GLIMPSE or Cygnus-X. You can use ESASky to see which region Spitzer has covered. ESASky has turned out to be a pretty useful tool. You can just right-click and “Search in SIMBAD”. There it opens SIMBAD and you can see the message: Query : coord 6.114d-0.416d (Gal, J2000, 2000.0), radius: 2 arcmin Those are the coordinates and you can copy them into the online vizieR catalog (search radius 1 degree). Here is the search as an example.

Now you have to copy the two tables in separate sheets in excel. I do this for short tables by selecting the text and then I copy it into excel. Another way is to use “Preferences” and using ;-separated-Values in the vizieR online catalog. After you saved the file you can open the file in excel via Data>From Text.


After you were able to copy the tables, you need an RGB-image with Spitzer Data. You can find the FITS-files for the IRAC2 (blue), IRAC4 (green) and MIPS24 in IRSA, here for GLIMPSE and here for MIPSGAL cutouts. It can be confusing at first.

In GLIMPSE there are two data products. One is a higher resolution (One pixel being 0.6 arcsecond) and a small field of view and the other being lower resolution (One pixel being 1.2 arcsecond) and a larger field of view. We need one image IRAC2 (look for Instrument) with the smallest disance (look for distance (arcmin)) and 1.2 resolution (look at the FITS filename). We need the same for IRAC4. You can download the file after clicking on this symbol download (please download the Cutout Image).

For the MIPSGAL cutout you have to look for the right image. Look at the Quicklook and search for images that look ok. The file should have a name similar to MG0060n005_024.fits Make sure you don’t choose the residual, std, covg or any mask file.


After you have done this very complicated task of downloading the right product, you need to create an RGB image. Please look at my toturial How to create an image from FITS-files

You should see something like this:

MWP DR2(blank).png
Image Credit: Spitzer Space Telescope | Image Processing: Melina Thévenot

Let us fill this with the bubbles and bow shock markings.

First the bow shocks. Just create a new textdocument with right-click:

textdocument

Copy the GLAT and GLON coordinates from the bow shock catalog into this text document and save the changes.

In SAO DS9 you can choose Regions>Load Regions.

load regions

You can select the textfile by choosing Files of type: All(*).

load

Now you have to choose the Format, in this case xy for plain xy-coordinates and the coordinate system. Because we used GLAT GLON, we need galactic and degrees.

load2

The new image has some green markings. Those are the positions of the bow shocks.

MWP DR2(only bow shocks).png


The Bubbles are more complicated. Again create a text file and add this header:

# Region file format: DS9 version 4.1
global color=black dashlist=8 3 width=2 font="helvetica 10 normal roman" select=1 highlite=1 dash=0 fixed=0 edit=1 move=1 delete=1 include=1 source=1
galactic

Each ellipse will be added in a single line with the format:

ellipse(GLAT,GLON,MajorAxis",MinorAxis",Theta)

In the excel file you can create this text with the formula “=verketten()”. I don’t know how this is called in English. I would translate it as chain or link. The formula adds different components into a string and we can copy this into our text file.

verketten
Click for larger version

Now you have to save the text file by using “save as” and choosing the File of type: All(*) option. Choose a name like bubble.reg It needs to be a .reg file.

ds9region.PNG

You can load the file (as described above for bow shocks) and this time you need to choose the Format: DS9/Funtools.

Now you should see something like this (I changed the color of the bow shock markers to yellow for my image)

MWP DR2.png

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