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ChaSeR: Search and Retrieval from the Chandra Data Archive
Reference
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:
For a graphical representation of the functional flow (PDF format),
click here.
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.
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". 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.
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.
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.
This page is maintained by the Chandra Data Archive Operations
group
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