• ChaSeR FAQ
• Feedback, known bugs, and current limitations
• Engineering Request data
• Download and installation

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The CDA Search and Retrieval interface allows Chandra users to browse the archive and retrieve any data - public or proprietary - provided that they are authorized to receive the products.

To run ChaSeR:

	chaser
  

NOTE: If you are not on your own machine and are using ssh to remotely log into another machine to run ChaSeR, you must explicitly set the DISPLAY environment variable, as in:

	setenv DISPLAY yourmachine:0.0
    

In general, we advise against running Java applications (this is not peculiar to ChaSeR) remotely.

The S&R application has three interactive screens:

• Observation Search
• Search Results
• Retrieval List

For a graphical representation of the functional flow (PDF format), click here.

Engineering Request Data

ChaSeR cannot access data products associated with Engineering Requests (ER). For access to ER data use RetrievER. Note that ERs do not contain any data that are of scientific interest and users may safely ignore them.

Observation Search

The first screen allows the user to specify constraints in order to find observations that match what (s)he wants.

Search Options

Each of the search parameters listed below acts as a constraint on the search for observations. A logical AND is applied to all constraints that are not left blank in order to decide which observations satisfy the search constraints.

Instrument

Select which instrument(s) should be used for the selected observations. These selections are combined in a logical OR.

Grating

Select either, both, or no grating. These selections are combined in a logical OR.

File input

Target names or positions may be provided through an ASCII file, rather than the input fields on the screen, allowing multiple searches to be executed in one query. When doing so, the other search constraints remain in effect. The input file needs to have on its first line the name(s) of the field(s) that are provided in the input file, separated by a tab if more than one. Valid fields are:

• Target Name; or
• RA, DEC; or
• LONG, LAT; or
• L2, B2 (Searching with galactic coordinates does not work properly and may not return an complete set.)

The search values are given, each set on a separate line, and again separated by a tab; the only whitespace allowed are blanks within a single value field (e.g., a target name or a sexagesimal string) and a single tab separating two fields on the same line. The coordinates and coordinate format should agree with what is specified on the screen. For example:

	RA	DEC
	123.4	12.3
	56.78	-45.678
      

or:

	RA	DEC
	08 13 36.00	+12 18 00.00
	03 47 07.20	-45 40 40.80
      

or:

	Target Name
	M81
	2MASX J06094582-21402
      

Target Name

Name of the targets to be selected: all targets containing the given string as a substring are selected; case-insensitive and blanks are ignored.

PI Name

Name of the observations' Principal Investigator: all PIs whose last names contains the given string as a substring are selected; case-insensitive.

Proposal Number

Restrict the search to a single proposal or a range of proposals.

Sequence Number

Restrict the search to a single Sequence Number or a range of Sequence Numbers.

ObsId

Restrict the search to a single ObsId or a range of ObsIds.

Exposure (ks)

Restrict the search to a range of exposure times (in ks).

Time range

Select only observations that fall in the specified time range.

Status

Optionally, only select observations with a particular status. Observations with status Archived have been publicly released.

Type

Optionally, restrict the search to observations of a particular type (CAL, GTO, GO, TOO, DDT).

Category

Optionally, restrict the search to observations of a particular category of objects.

Search by Position

Coordinate System

Selects the coordinate system of input and output coordinates independently.

Equinox

Selects the equinox of input and output coordinates independently.

hh mm ss.s/ +/-dd mm ss

Use sexigesimal format for input and output coordinates independently.

decimal degrees

Use decimal degrees format for input and output coordinates independently.

RA, Dec, Radius

A search area may be specified, either as a cone (single RA and DEC, and a cone radius) or as a rectangle on the sky (ranges in RA and DEC). The choice is made through a pop-up window.

Display Options

Table

The results of the search will be displayed in the Search Results window.

File

The results of the search will be written to a file; the user has the choice of summary or detailed information and will be asked for a file name.

Order by

The search results may be ordered by any of the parameters appearing in the summary listing.

Action Buttons

Submit

Submit the search query. If the Table option is selected, the results will be returned in the Search Results window. If file output is selected, the user will be queried for a file name.

Clear

Clear all fields.

Use SIMBAD

Use the SIMBAD name resolver to transform a target name into celestial position.

Help

A few Help items.

Exit

Exit ChaSeR.

Search Results

The results of the search are presented in tabular form. Note that the cursor may be used to change the width and the order of the columns.

Observations may be selected by clicking on them. Control-clicking selects multiple entries. A contiguous range is selected by clicking on the first and Shift-clicking on the last.

Action Buttons

Order by

The list may be ordered by any column.

Detail

Provide detailed information on selected observations.

Images

Display quick images of the selected observations. If these include proprietary data, the user is asked to log into an authorized account (for publicly observations select status Archive or consult the public release date).

Save

Save the list into a file.

Return to query form

Return to the Observation Search screen.

Help

These web pages.

Exit

Exit ChaSeR.

Select Data Products

Select Products

The data products are divided into three categories: Primary, Secondary, and Supporting. By default all products in the Primary and Secondary categories are selected. However, the user may also customize the contents of these categories by clicking on the Primary and Secondary buttons. Supporting data products need to be explicitly selected.

Please be aware that Supporting data products need to be retrieved from a different archive server and that therefore retrievals that include supporting products are inherently slower.

The FILETYPE that is displayed in these menus is the value of the CONTENT keyword in the FITS files. See the list of data products.

Add to retrieval list

Add the selected products for the selected observations to the Retrieval List.

View retrieval list

Go to the Retrieval List screen.

Retrieval List

The user may edit the contents of the shopping cart by selecting items and deleting them.

Action Buttons

Delete selected

Delete the selected product items from the Retrieval List.

Delete all

Delete all products from the Retrieval List (empty the shopping cart).

Login

Change to a different archive account. This is in case the users wants to retrieve proprietary data; if the user omits this step and there are proprietary data in the cart, (s)he will be asked during retrieval. During this step the user will also be allowed to change the password.

Return to search results

Return to the Search Results screen. This allows the user to add more items to the shopping cart or to start a new retrieval process (in the latter case, empty the shopping cart before returning to results).

Help

Display these web pages.

Exit

Exit ChaSeR.

Browse selected products

Brings up a new window with a list of the actual data products that are included in the shopping cart, with file names and file sizes. One should note that the sizes are for the uncompressed products while transfer will take place in compressed form; on average, the compression is about a factor 2. Users are well-advised to check the size of their download before executing the retrieval.

Retrieve selected products

Starts the retrieval process, either directly to a user-specified directory or to the CDA ftp site. In both cases the data products are collected in a single tar file. But the latter method is significantly faster; in that case a retrieval report will be deposited in the file chaser.log in the user-specified directory (Place files in) which includes the name and location of the tar file. If the user requests proprietary data, (s)he will be asked to log in before the retrieval is executed. During this step the user will also be allowed to change the password. If the user elects not to log in, or logs in to an account that has no authorization for the requested observation(s), the proprietary data products are deleted from the retrieval request but all public products are retieved. The tar files will contain one directory per ObsId.

Cancel Browse/Retrieve

Cancel browsing or retrieval in progress.

Stage in anonymous ftp area

Retrievals will be staged in the CDA anonymous ftp area for later retrieval by the user. The exact location is provided in the log file. The files will remain in this location for 24 hours.

Download via application

The retrieval tar file is transmitted directly through ChaSeR. In principle, this method is slower that direct ftp, though this may not matter for users at the end of a narrow-bandwidth line; however, it is also safer, in case of transmission problems. It is only recommended for small transfers.

Place files in

The directory where directly downloaded tar files are to be placed. It is also the directory where the retrieval log is placed. Make sure you have write privileges in this directory.

See the Guide to Chandra Archive Data Products for the list of data products available.