Finder Chart: Catalogs

Note that catalogs are available in two ways: (1) from the front page, via your initial search, or (2) via a blue tab that appears at the top of the page only after you have performed at least one search -- you need to have something on which to overlay the catalog before it will let you search for more catalogs. You can choose from any of a wide variety of catalogs for overlaying on your visualized data.

Contents of page/chapter:
+Initially Searching on Catalogs - Catalogs from the Search Page
+Catalogs from IRSA -- Overlaying catalogs from IRSA
+Catalogs from disk -- Overlaying your own catalogs
+Catalogs from VO -- Overlaying catalogs obtained via the VO
+Columns and filters -- Interacting with catalogs
+Plotting catalogs
+Example of catalog plots #1: Catalog pulled after searching
+Example of catalog plots #2: Catalogs pulled during initial search


Initially Searching on Catalogs - Catalogs from the Search Page

From the main search page (for more information, see searching), you can ask it to "Search Corresponding Catalog(s)." Specifically, you can ask for all the sources in the corresponding catalogs within the image boundary, or just within a certain search radius. You can further constrain it by selecting "One to One Match" -- in this case, it will find just the closest source to your position within your selected search radius, and only that closest source.

If you search on catalogs from the search results page, then Finder Chart will overlay these catalogs on your images as additional layers. These catalogs behave in the same way as the catalogs described in the rest of this section, so read on!

However, if you search on catalogs from the main search page, Finder Chart overlays the catalogs on your images right away, and it does so in a way that is quite powerful, but may be initially confusing. In order to understand what it is doing, you need to use the visualization tools, so there is more information (including an example) in the Visualization section. Critical to understanding what it is doing (and how you can change it) is the concept of the "selected image" -- different things are overlaid on different images (and image sets), and your choices change depending on which image you have selected. If you choose to search the catalogs just over a small radius, and/or further constrain it to just find the closest source (one-to-one match) to your target, the overlays of the catalogs will (presumably) all be over the same, single source, and it will be much less clear that the catalogs are overlaid at all, much less that the catalogs are different on each set of images. But, it is behaving in the same way.

Catalogs from IRSA

By clicking on the "Catalog" tab (which also looks like a button), a window appears with several options, as follows.

By default, it pre-fills your search region to match what you have been doing with your current object. If you would like to change the region of the search for the catalog search, change the coordinates of the polygon it shows by default, or (easier), change the search method to "cone" and click on "modify target" and enter the new information. You can customize the search for options beyond a cone search (e.g., an elliptical search). The default cone radius is 500 arcsec. Caution: pick your units from the pulldown first, and then enter a number; if you enter a number and then select from the pulldown, it will convert your number from the old units to the new units. There are both upper and lower limits to your search radius; it will tell you if you request something too big or too small. Note that these limits are catalog-dependent.

You then need to specify the catalog you want to search. In order to help it give you a specific list of choices, you need to first tell it the project (default: 2MASS) and category (default: 2MASS All-Sky Release Database). After you have selected these items, on the right, you can pick the specific catalog (default: 2MASS All-Sky Point Source Catalog). To change catalogs, first select the "project" under which they are housed at IRSA, such as 2MASS, IRAS, WISE, MSX, etc. The options under the "category" and the specific clickable catalog on the right change according to the project you have selected. A short description is provided for each of the catalogs, with links for more information (including definitions of the sometimes cryptic column names); an example of this link for more information is here:

You can also set restrictions on specific columns by clicking on "Set Column Restrictions" on the left hand side, under the "category" selection pull-down menu. A new window will open up with the available column names in the corresponding catalog, and you can choose what to display, and filter what is returned (for example, only return objects with values in column y that are greater than x). If you add more than one restriction, they are combined logically using an "AND" operators; be careful, because you can thus restrict data such that none of the catalog meets your criteria.

Power user tip: By default, this interface may show you fewer columns than are available in the full catalog. By clicking on "Set Column Restrictions" and selecting "long form" from the pulldown at the top of the pop-up window ("Please select long or short form display"), you can access the full range of available columns. In some cases, there are literally hundreds of columns that you can access!

Click on "Search" to initiate the search. It will load the catalog into a tab of its own on the bottom of the screen (in the catalogs window pane). The catalog objects will also be overlaid on the images you have loaded. You can also make an x-y plot from the catalog (for more on the x-y plots, see below). The image and the catalog representations are interlinked -- clicking on a row in the table shows it on the image and vice versa.

To close the catalog search window without searching on a catalog, click on "Close" in the upper left.

On the speed of the catalog results...

If the catalog search is successful quickly, it will promptly return the results in a tab of its own.

NOTE THAT the search may take a long time to return, especially if you have asked for a large catalog, and you may think that nothing has happened, but be patient and eventually it will either spin off to the background monitor (from which you can load it into a tab), or return a tab directly.

Searches that take longer than a few seconds get spun off to the background monitor. If it does spin off to the background monitor, it will dynamically update to reflect its status, and will let you know when the catalog is ready to download or display. A popup appears asking if you want to load the catalog. Either click on the popup or explicitly open the background monitor and click on the catalog name to load it into a tab of its own.

Use large search radii with caution! Be sure you understand how many sources you are likely to retrieve. Searches that retrieve more rows will take longer. Searches that retrieve millions of rows will take quite a while.

Note that if you overlay a catalog consisting of tens of thousands of sources, to save bandwidth, what is overlaid on your image at some locations may be a larger symbol representative of several sources at that location; if you then save a regions file from the catalog overlay, then you will end up with fewer sources in the regions file than you have in the full catalog.

Loading your own catalogs

By clicking on the blue "Catalogs" tab, you are by default dropped into the interface for searching for catalogs at IRSA. However, you can pick another tab from the top left, "Load Catalog", to load your own catalog.

Your catalog needs to be in IPAC table format, which is a varietal of plain text. IRSA has a table reformatting and validation service which may be helpful, or you can download just about any catalog you find through IRSA, and copy that format.

Your table file MUST have RA and Dec values, and unless it is specified, it assumes J2000.

You can add a "SYMBOL" parameter to change the shape (X, SQUARE, CROSS, EMP_CROSS, DIAMOND, DOT) of catalog marks, e.g.:


You can add a "DEFAULT_COLOR" parameter to assign a CSS color name or a HEX value to catalog marks, e.g., either of these two:

\DEFAULT_COLOR = lightcyan
You can find the CSS color code or the CSS color HEX values online.

Your catalog is then shown (and interacted with) in the same way as the other catalogs described here.

Catalogs from the VO -- Overlaying catalogs obtained via the VO

(VO= Virtual Observatory.)

By clicking on the blue "Catalogs" tab, you are by default dropped into the interface for searching for catalogs at IRSA. However, you can pick another tab from the top left, "VO Catalog", to search for and load catalogs from the VO.

As for the IRSA catalog search, the tool pre-fills the target position with the coordinates of the target with which you have been working. In this case, you are limited to a cone search, so the next option is the cone search radius. As usual, pick your units from the pulldown first, and then enter a number; if you enter a number and then select from the pulldown, it will convert your number from the old units to the new units. There are both upper and lower limits to your search radius; it will tell you if you request something too big or too small.

If you know your VO URL already, you can jump down to the Cone Search URL box and type or paste your URL into the box and hit search.

More commonly, however, users do not know a priori which URL to use. Type your desired keywords into the keywords box and click on "Search Registry". All of the URLs it finds for your keywords within the VO registry service are shown in the box. Locate the one you want to use, and click on "Use" on the far left of the corresponding row. The "Cone Search URL" is populated properly for that catalog. Click on "Search" to initiate the search.

The search results are then shown (and interacted with) in the same way as the other catalogs described here.


Note that searching the VO means that you are using resources not specifically housed at IRSA, so servers may be down, or timeouts set, or limits on numbers of returned sources, etc., that are beyond our control. In most cases the solution is to specify as precise a search as possible. Here are the links to VO registries that we are using, just in case you want to do more flexible searches of the registry. The URL you enter into the box in Finder Chart, though, must be a Cone Search base URL (not containing RA and Dec parameters, which are inserted into the URL by Finder Chart in response to the search parameters you give it).

The master list of registries is here. You can also search the registries directly via that link (as opposed to via the IRSA tools).

Columns and filters -- Interacting with catalogs

After you have loaded a catalog, it appears as a tab in the bottom window pane. Additional catalogs you load appear as additional tabs in this window pane. To see more of the window, grab the divider between the two window panes and slide it up, or use the expand arrow icon () to enlarge the window pane to take up the whole window.

The table is shown exactly as it appears in the corresponding database (or as it appeared on your disk), with all columns as defined for that catalog. To understand what each column is, please see the documentation associated with that catalog. (For IRSA catalogs, this documentation is available via the catalog searching popup window, see figure below, or by navigating through the IRSA website.)

The tab (and table) name itself is the name of the catalog file as stored on the system at IRSA; it is a little cryptic, but the first few words should make it clear whether it is WISE, 2MASS, etc. To remove the tab, click on the blue "X".

Immediately below the tab name, there are several symbols:

which we now describe.

The first thing to notice is that only the first 50 rows of the retrieved catalog are displayed in the table. In the example, there are 1358 sources that were retrieved as part of the search. The left/right black arrows plus the page number allow you to navigate among these 'pages' of 50 sources each. Note that the entire set of results (not just the 50 rows you are currently viewing) can be sorted alphabetically by clicking on any column's name.

By default, the catalogs you retrieve via this search are NOT overplotted on the images. (They used to be overplotted in a previous version of this tool, but given the potential for confusion since catalogs can now be searched from the front page, this behavior was changed.) To overplot the catalog (the entire catalog, not just the first 50 shown on the first page of the catalog tab), go to the layers icon and turn on the catalog overlay.

Going from left to right along the top of the catalog tab, the next icon represents a filter: Filters are a very powerful way of exploring the catalog data. Click on this icon in order to start the process of adding filters. A text entry box appears above each of the current catalog columns, with a small version of the filter icon corresponding to that row on the far left. You can type operators and values in these boxes -- hit return after typing or click in another box to implement the filter. For fields with a limited set of choices, instead of a text entry box, a filter icon will appear; click on it to select from the available choices. As an example, to show only those sources with declination above a certain value (say, 31 degrees), type "> 31" in the box above the "dec" column. Or, if you have retrieved a WISE catalog and would like to only view the objects with a W1 (3.4 micron) profile-fitted magnitude less than 6 magnitudes, above the 'w1mpro' column, type "< 6" in the form.

After you impose a filter, then the number of rows in the catalog is restricted according to the rules you have specified, and the "filters" icon on the top right of the catalog pane has changed to remind you that there has been a filter applied, in this case just one filter: . To clear the filters, click on the cancel filters icon (which also appears after you impose filters): .

Note that the filters are logically "AND"ed together -- it will impose this AND that AND this other restriction. You can relatively easily restrict things such that no data are left; if that is the case, you will get "There are no data to display." You can then cancel all the filters at once via the cancel filters icon (), or remove them individually by hand by editing the filter boxes at the top of each column, just as you did to impose the filters.

The available logical operators are :

Troubleshooting: Note that if you accidently type letters in the numerical filter boxes, it doesn't particularly give you a helpful error such as, "I'm baffled as to what you want me to do because you've typed text for a numerical filter". It just tells you that there "are no data left to display" where, say, RA is "< 10p" (as an example of a common typo). If you unexpectedly get "no sources left", double-check your filter boxes for typos.

You can also interactively impose filters from plots you make from the catalog - see the next section.

The next icon is -- clicking on this changes the table display into a text display. The icon then changes to -- click this again to return to the default table view.

The next icon is which is "Save" -- this is how you may save the whole catalog (NOTE: the WHOLE TABLE, not just the first 50 rows shown) to your own local disk. If you have filtered the catalog down, it will save the filtered catalog (though as of this writing, the total number of rows retrieved in the table header will still be the original number). It will save it as an IPAC table file, which is basically ASCII text with headers explaining the type of data in each column, separated by vertical bars. By default, the file is called "GatorQuery.tbl" because, under the hood, the software is talking to the IRSA General Catalog Query Engine, powered by Gator.

The next to last option on the top of the catalog tab is this: . Clicking on this icon brings up options for the table, e.g., how many rows are displayed per page, and which columns are shown. By default, all columns are shown. The default page size is 50 rows. Note that expanding the page size to numbers much greater than 50 may result in a substantial performance degradation (e.g., your browser will appear to freeze or not appear to be doing anything while it manages and renders the large table).

Note also that if you resize columns, and then go and add new columns, the original columns are resized back to their defaults after the new columns are added.

Finally, when your mouse is in the catalog window pane, you see this as the last option on the top of the catalog tab: . Clicking on this expands the catalog window pane to take up the entire browser window. To return to the prior view, click on "Close" in the upper left.

Plotting catalogs

You can plot your catalog after it has loaded. This is true whether you searched for catalogs during your initial search, or after your initial search via the catalogs tab. The plots are another view of the catalog; by default, the catalog comes up in 'table' view, and you can swap back and forth between the 'table' and 'plot' view. After you have loaded a catalog, these icons appear in the upper right, just above the image results pane: The first one is table view, and the second is plot view. The current view is boxed in green. Click on the icon to change views. To see more of the catalog while still viewing images, click and drag the slider between the panes to enlarge the plot window pane.

To obtain a full-screen view of your plot, click on the expand icon in the upper right of the window pane when your mouse is in the window: . To return to the prior view, click the "Close" arrow in the upper left.

The plotting tool, by default, starts with RA and Dec plotted. Note that it does so strictly mathematically correctly -- that is, RA increases to the right (the reverse of astronomical convention). To change what is plotted, click on the gears icon in the upper left of the plot window: . Configuration options then appear to the left of the plot.

You can add or remove the gridlines via the "Grid" checkbox.

You can choose a single column to plot against another column -- if you have loaded a WISE catalog, you could plot w1snr vs. w1mpro. You can start typing a column name into the X and Y boxes, and it will help provide you viable options from the column headings. Alternatively, you can click on the "Cols" link to bring up a pop-up window with all the columns for that catalog listed. NOTE THAT you must type in the column name exactly matching the column headings as displayed. By default, it echoes the x and y labels and units from the original table, but you can change this by clicking on the triangles below each entry box (e.g., make the label "SNR in WISE-1" rather than the more cryptic column header "w1snr").

You can also do simple mathematical manipulations. For example, if you have loaded a WISE catalog, you can plot w1mpro vs. w1mpro-w4mpro. However, note that as of this version, the axes are from min to max in the strict mathematical definition of the term, so in this example, the fainter W1 objects are at the top of the plot. As a workaround for this, plot -w1mpro vs. w1mpro-w4mpro to get the axes aligned in the way you are expecting such that brighter objects are at the top of the plot.

Note that in this example, which represents more than 67,000 sources, there are so many sources in this diagram that it has binned them up, and the plot shows shades of grey corresponding to how many points are represented at that location in the plot. The lightest shade of grey (and smallest points) represent one point in the plot at that location, and the darkest shades of grey (and the largest points) represent many more points in the plot at that location. The reason it does this is to more fairly represent the point density -- and to make the plotting faster.

If you move your mouse over any of the points (you may need to click on a point at least initially), you will get a pop-up telling you the values corresponding to the point under your cursor, even if there are many catalog rows represented.

You can change the bin size and shading. Under the "binning options" on the left hand side (in the plot options), you can choose whether the binning is set automatically, or by you. You can also choose if the grey shading is set linearly or logarithmically.

In order to have the tool plot one point per catalog row, you need to zoom in or otherwise restrict (see paragraph after next) the data such that there are 'few enough' points represented in the plot. If there is just one point in the plot that needs to be rebinned, all of the points will be small black boxes.

If you have zoomed in enough such that there are just black boxes -- one object per point -- you can change the plot style such that the points are connected or unconnected.

You can also restrict what data are plotted in any of several different ways. You can set limits based on the "more options" (click on the triangle next to "more options") on the lower left of the plotting window pane, or you can use a rubber band zoom, as follows. Click and drag in a sub-region of the plot. The icons in the upper right of the plot change corresponding to what you can do, in this case to these: . They are, from left to right: zoom in on the region you have selected, select the objects in the catalog, filter the catalog to leave only those objects, or expand the plot to take up the whole browser screen. If you click on the zoom icon, then the plot axes change to encompass just the sources you have selected (and the icons in the upper right change, leaving this -- if you click this, you go back to the original view). If you click on the select icon, then the plot symbols corresponding to your selection change shape and color, the corresponding objects overplotted on the image in the image window pane change color, and (if you change back to the table view of the catalog), the rows (corresponding to those sources) in the catalog are highlighted. (Also, the icons in the upper right of the plot change, leaving this -- if you click this, you deselect the sources and go back to the original view) If you click on the filter icon, then the catalog view is filtered down, restricted to just those sources you have selected, and the filter notes in the upper left of the plot window (and in the table view of the catalog) change to remind you that you have a filter applied. Only those sources that pass the filter are shown overlaid on the image(s). (This is the behavior of 'filter', as opposed to 'select'; the former restricts what is shown, the latter just highlights the objects.) You can also pull up an interactive filter on the catalog itself from the plot view -- click on the filter icon near the setting icon on the left. For more on filters, see the filter section.

Another option within the "More Options" in the lower portions of the plot settings has to do with the display aspect ratio. You can make a plot more square or more rectangular by changing the x/y ratio here (set it to 1 for a square plot), or you can tell it "fit": make it fit in the available space, or "fill": make it as big as possible in the window.

Want to save a plot to file? At this time, the best way to do that is a screen snapshot. On a Mac, this is accomplished via holding down command, then shift, then 4, then let go and your mouse cursor changes. Hit the space bar to select the window over which your mouse is hovering. Your mouse cursor changes again, and hit the mouse button. A snapshot is then saved to your Desktop, tagged with the date and time.

Once you have made an x-y plot, the plot is then effectively treated as another 'image' in the stack of images you have loaded into the tool. In the Visualization section, it describes various features, including blinking images, and removing images from the blink sequence. If, after you make a plot, you want to blink or tile some of the FITS images, you will need to remove the plot from the image sequence, as described in the Visualization section.

Example of catalog plots #1: Catalog pulled after searching

Example: Plotting [W1] vs. [W1]-[W4] in a star-forming region

In a star-forming region defined for this example, we are trying to find young stars. We will search in the WISE AllWISE catalog. Stars without circumstellar dust should be at a variety of W1 brightnesses, but all have [W1]-[W4]~0. Background galaxies should be faint and red. Stars with circumstellar dust (e.g., young stars) should be bright and red. Here, we will make a plot, identify a bright and red object in the plot, and find where it is in the WISE images.

  1. Launch the Finder Chart tool. Search on IC1396. Simbad's interpretation of the coordinates are fine. Change the default image size to be 1/2 degree (pick the units first, then enter the number) and display size (Medium) are fine. Select DSS, 2MASS, and WISE. Now, at this point, we could click on "Yes" for "Search Corresponding Catalog(s)", then tell it to "search within the image boundary." But we want to be mindful of the numbers of sources it is likely to find over half a degree in all of these catalogs (hint: a LOT). At this point, we are only interested in the WISE catalog. So, let's leave "Search Corresponding Catalog(s)" set to "No.". Click "Search." Wait for it to come back with the results.
  2. Now, let's search just for the WISE catalog in this region. Click on the blue "catalogs" tab. By default, it is set to cover a region similar to our original search, but we want to change that. Change the search method to "cone." Leave the target coordinates as they appear. Change the units of the radius pulldown to "deg" and enter 1 degree in the cone radius. Select Project=WISE. Select the AllWISE Database, and the AllWISE Source Catalog. Click "Search."
  3. You may have to wait a bit for the catalog to be returned. It will ask you if you want to load the results. Say yes.
  4. It may take a few more seconds to load and display the catalog, because the catalog is ~67,000 sources. Note that all ~67,000 sources are not yet overplotted on the images. To get them overplotted, select an image, click on the layers icon in the image toolbox, and turn the corresponding catalog layer on over all the images. Grab the slider between the window panes and drag it up to see more of the catalog (and less of the images). Note that selecting a source in the image makes its corresponding row in the catalog turn green; this works the other way too in that clicking on a catalog row highlights the source in the image. Note that for this example, we have loaded a catalog over a much larger region than the image covers, so if you pick a source at random from the catalog, it might not be in the images. (In the image, your search target is a blue circle, the selected source in the image is a default blue square with an x in it.)
  5. In the upper right of the browser window (just above the image window pane), there is this display: . By default, the catalog is shown as a table. Click on the plot icon (far right) to view and interact with an x-y plot. It may take a few seconds to plot all ~67,000 sources.
  6. The plot comes up with an RA/Dec plot by default. Two things to note: (1) RA is increasing to the right, not the left, because it is plotting strictly mathematically min-to-max. (2) The points are binned up such that each point represents more than one row of the catalog. Mouse over or click on a point to see how many rows are represented:
  7. Click on the expand icon in the upper right of the plot window. If you don't get the plot right away, click on the one-image-at-a-time icon in the expanded view if necessary () and scroll through to find the plot.
  8. Click on the gear icon in the upper left of the plot window.
  9. Enter in the x box: w1mpro-w4mpro. This is WISE-1 profile-fitted measurement in magnitudes minus WISE-4 profile-fitted measurement in magnitudes, or [W1]-[W4].
  10. Click on the triangle next to "X label/unit", and enter "[W1]-[W4]" for the label. Enter "mag" for the unit.
  11. Enter in the y box: -w1mpro (the minus sign is important to put the bright objects at the top of the plot, but note that the numbers as plotted will then be negative.)
  12. Click on the triangle next to "Y label/unit", and enter [W1] for the label. Enter "mag" for the unit.
  13. Leave the "grid" box checked.
  14. Click "Apply."
  15. Obtain this plot:

  16. Note that all of the points are shades of grey, denoting that at least one of the bins shown in the plot is representative of more than one row in the catalog.
  17. Click and drag from corner given approximately by (2,-6) to (7,-11).
  18. The icons in the upper right change after you do this, and we want to zoom on this region. Click on the magnifying glass with a "+" inside.
  19. After we zoom, there are far fewer shades of grey in the points. This means that there are far fewer points in the same location in the plots. Zoom enough, and every point will turn into a small, black square, which denotes that every point shown is truly a single row in the catalog.
  20. Find the brightest source near [W1]-[W4]~4.5. Click on that point.
  21. Click on "Close" in the upper left to return to the window pane view.
  22. The bright, red object we selected in the plot is highlighted in the overlays on top of the images and in the catalog table view. To find it easily in the image among the ~67,000 sources, you can do one of two things:
    1. Click on the expand image icon in one of the loaded WISE images. Click on one of the resize icons until the highlighted source is visible. Zoom in some more and click and drag the image to center it, if desired. Note that you may have to select another point in the plot and then go back to this bright red point in this example to get it to re-draw the highlighted point on the image.
    2. OR... Click and drag around this point in the plot view of the catalog. Click on the blue filter icon in the upper right. The plot at this point looks silly, but only that point is left in the overlay of sources on the images and in the catalog table view. (If you have been following closely, it should be J213817.31+573121.9.) As for the prior option, you may need to move around in the WISE image until you can find it.

Example of catalog plots #2: Catalogs pulled during initial search (using one-to-one matching)

Example: Searching all over the sky for objects with SDSS, 2MASS, and WISE data, and plotting [W1] vs. [W1]-[W4]

This example provides an opportunity to explore images and catalogs (including 1-to-1 matching, which can be powerful but may be confusing). This example does not walk through every source in detail, but sources can be found in this list where proper motions are high (such that 1-to-1 matching doesn't work well), and/or coordinates are bad, and/or the sources are not point sources, and where the WISE measurements have to be pulled out of the reject catalog.

  1. I have a target list containing 316 targets, which I have prepared in IPAC table format, of some objects claimed to be rapidly rotating K giants. They are all over the sky. Some are claimed to have IR excesses, and I want to see if they have WISE excesses, as well as look at the WISE images for them, just as these fine folks did. Some of the coordinates are good to within an arcsecond, and some are very poor coordinates. Many of the sources are very bright (some saturated).
  2. Launch the Finder Chart tool. Select "multiple positions". Click on "choose file" and locate the IPAC table file with the targets on disk. The default image size, and display size are fine. We are interested in these targets in all possible images here, including IRAS. Select all the surveys. Set "Search Corresponding Catalog(s)" to yes. "Search radius" is the only catalog option now, because we are using mulitple targets. Leave the default search radii for each catalog. Click on the box for "One to one Match". This will make one line in each output catalog for each line in the input catalog, and it will take the source in each catalog closest to the input position within the search radius tolerance. Click "Search."
  3. It takes a bit to load in all the images and catalogs. When it loads, it looks like this:

    Things to note: The left pane has the list of targets, the right pane has the images, and the bottom pane has the returned catalogs. The green row in the list of targets is the target whose images are shown on the right. No data were found for SDSS for this target, but at least it doesn't take up any screen area. (There are other targets in the list for which there are SDSS data.) There are 4 catalogs loaded in the bottom window pane. The catalog that is on top in the screen shot above is that from IRAS. We asked it for one-to-one matching within 90 arcseconds for IRAS. Out of the targets shown, it found a match only for target 2, but it found one within 1.37 arcseconds. The catalogs are overlaid in a survey-by-survey fashion -- the 2MASS catalog is overlaid on the 2MASS images, and the WISE catalog is overlaid on the WISE images, but because we asked for just one source per catalog, and because they are nicely coincident with the target position, it does not LOOK like the catalogs are overlaid... but they are!
  4. These targets are ones for which we would like to know if there are any IR excesses. Click on the WISE catalog tab in the catalog window pane. Go to the upper right of the window, to "view options" (). Click on the plot icon. The plot appears on the bottom, probably too small to read at all. Put your mouse over the plot window pane, and look for the expand arrows (). Click on them.
  5. Now we have a full-screen view of the plot, but it's pretty useless because it is a plot of two integer counters (the first two numerical columns it found in the catalog). Click on the gear icon in the upper left of the plot window.
  6. Enter in the x box: w1mpro-w4mpro. This is WISE-1 profile-fitted measurement in magnitudes minus WISE-4 profile-fitted measurement in magnitudes, or [W1]-[W4].
  7. Click on the triangle next to "X label/unit", and enter "[W1]-[W4]" for the label. Enter "mag" for the unit.
  8. Enter in the y box: -w1mpro (the minus sign is important to put the bright objects at the top of the plot, but note that the numbers as plotted will then be negative.)
  9. Click on the triangle next to "Y label/unit", and enter [W1] for the label. Enter "mag" for the unit.
  10. Leave the "grid" box checked.
  11. Click "Apply."
  12. Obtain this plot:

    Note that each one of the points as shown is a small black box, so each point represents one line in the catalog (the data are not binned). The things brighter than [W1]~3 are likely saturated, given the structure seen in this plot. There are some bright red things, and some faint red things.
  13. Locate the bright red thing near [W1]-[W4]~3, [W1]~2. Click on it. Close the expanded plot view. Go back to "View options" (at the top right) and pick the table view. Find the highlighted object in the list, which corresponds to this bright red object. It is number 241.
  14. Go up to the target list on the left. Click on the filter icon to reveal the filter boxes. Locate the "in_row_id" column. Type in the filter box "=241" and hit return.
  15. The target list is now filtered down to just be target #241, and the images change accordingly. Go and inspect the images in all bands. This sure looks like a point source!
  16. Go back to the Plot view of the WISE catalog window. Click on the expand arrows. Locate the reddest source there. Click on it. Close the expanded plot view. Go back to "View options" (at the top right) and pick the table view. This red object is object 269 in the list.
  17. Go up to the target list on the left. Click on the filter icon to reveal the filter boxes. Locate the "in_row_id" column. Type in the filter box "=269" and hit return. Look at the images. There does not seem to be a point source there at POSS or 2MASS bands, but there is a source with a very steeply rising SED through the WISE bands; it looks like it might even be there in IRAS. We conclude that this is probably not a K giant.
  18. It is useful in general to look at each set of images in concert with the catalogs. In the interest of space, we do not work through each of these ~300 sources, but this target list provides a great example of some of the things to look for. In this list of targets, at least one source has substantial proper motion, such that the automatic catalog 1-to-1 matching is not going to work well enough to find the true match across catalogs, and you have to do a separate search via the catalogs tab to find its true measurement at the other bands. Three sources have WISE measurements that do not appear in the AllWISE catalog, but erroneously instead in the catalog of WISE rejects - that, too, you can search via the 'catalogs' tab. Many of these sources appear in other catalogs housed at IRSA, such as the Akari catalog. Many of these sources really are saturated (as you can see in the plot above), and checking the images helps assess the degree of saturation. Several of the sources were point sources for IRAS but not for WISE. Several of the IRAS point source positions are likely physically associated with but not well-matched to the positions of the brightest source seen in the WISE images, meaning that 1-to-1 matching fails because human judgement is required to make the match. There are other irregularities as well. We encourage you to explore. (The journal article that came out of this work has long discussions of individual targets if you want to learn more about them.)
  19. Saving the catalogs: For each of the catalogs, click on the diskette icon and save it to disk. Because each catalog has 316 data rows exactly, merging these lists together is straightforward. (Note that the catalogs might have different lengths of header information, however!)
  20. Saving the images: To save the FITS images to disk, click on "Download" in the upper left of the image window pane. From the pop-up, select "all targets", FITS, "separate by object". Click "prepare download" and wait until it is done to download it. Unzip it, and you have the images sorted by target name to browse offline. You can also save png images or pdf files (both of which include stretches and overlays as you customize interactively).