II. User's Guide to the WISE Preliminary Data Release

4. Ancillary Products

c. Atlas Image Frame Cross Reference Table

The WISE Preliminary Release Atlas Image Frame Cross Reference Table provides a listing of all individual Single-exposure image frames that contribute to each Atlas Image in each band. It can be used to determine which frames contribute to a given Atlas Image, or it can be used to determine to which Atlas Images a particular Single-exposure image frame contributes. The criteria used to select and filter the scans, framesets and frames that are used as input for the Multiframe pipeline processing that generates the coadded Atlas Images and extracted Source Catalog are described in V.2.

i. Table Format Description

The following table contains brief descriptions of the parameters provided for each record the WISE Preliminary Data Release Atlas Image Frame Cross Reference Table.

The columns in the following table are:

Column Name: The parameter name in the Catalog table. Click on this to go to the section of the Explanatory Supplement section in which the derivation and/or usage of that parameter is described in greater detail.

Format: The ASCII-equivalent format of the field in the Catalog, expressed in "C"-readable notation. This is useful when parsing the aligned tabular output from IRSA/Gator. Although the data values will conform to these formats, the actual width of the field in the Gator output may be padded with extra blank spaces to accommodate column headers. Note that some fields contain null values that will require special handling when parsing Catalog tables from IRSA/Gator output.

Units: The units of the parameter. A value of "----" in this column means that the parameter is dimensionless or non-numeric.

nulls: A "yes" in this column means this parameter can be null in the Catalog. A "no" means there will always be a value in this column in the Catalog.

Description: A brief description of the parameter and its values.

Column Name	Format	Units	nulls	Description
coadd_id	%20s	----	no	tlas Tile identifier from which source was extracted. The identifier has the general form: RRRRsDDd_[trev], where RRRR = Tile center RA in deci-degrees, truncated not rounded (e.g. RRRR=int[10ra]). s = Tile center Declination sign ("p"="+", "m"="-") DDD* = Tile center Declination in deci-degrees. For positive declinations, the tenths of a degree is truncated not rounded (e.g. DDD=int[10dec]). For negative declinations, the tenths of a degree is always truncated leftward on the number line (e.g. DDD=ceil[10abs(dec)]. [trev] = Disambiguation string. t - Tile type ("a" = Atlas) r - Data Release ("a" = Preliminary) e - Sky coverage epoch ("1" = first) v - Processing version. The disambiguation string is always aa11 for Tiles in the WISE Preliminary Data Release. For example, the identifier of the Atlas Tile with center at (α,δ = 304.13896,-13.63000) is 3041m137_aa11.
band	%1d	----	no	WISE band number. 1=W1, 2=W2, 3=W3, 4=W4.
scan_id	%6s	----	no	Scan identifier. This is a six character string that identifies a block of survey exposures that are acquired between two flight system maneuvers, such as reorientation of the instrument boresite near the ecliptic poles, or slews to acquire TDRSS for data downlink contacts. Because maneuvers often take place near the ecliptic poles, the scan number is roughly associated with a half-orbit's worth of images. However, scans can cover less or more than half of the arc between ecliptic poles. The scan_id has the general form SSSSSx, where SSSSS is a zero-filled, five-digit integer that is twice the WISE orbit number. The orbit number increments each time the flight system passes the north ecliptic pole (NEP). Orbit number 1 was defined to start with the fictitious NEP passage immediately prior to WISE launch. x is a letter assigned based on sequential count of scans started in a specific half-orbit. The first scan has x="a", the next x="b", up to a maximum of x="d" for scans in the Preliminary Release. The first scan whose data are used in the Preliminary Data Release is scan 00936a. This was the first scan after the NEP crossing in the 468th WISE orbit. The final scan included in the Release is 04125a, the first scan after the SEP crossing in the 2062nd WISE orbit.
frame_num	%3d	----	no	Number of the frameset on which this source was extracted. The identifier has the general form MMM, a zero-filled three-digit number. The frameset number is computed based on time bins which count from the scan start time: fr_num = int[(((frame_utc - dt_beg) - scan_start_utc)/bin_size] + 1 where int[] means truncate to an integer frame_utc is the nominal frame exposure center UTC (when the boresite crosses the image center) in seconds dt_beg is 4.4s. This is a nominal offset to approximate when the exposure began scan_start_utc is the scan start time in seconds bin_size is 10s. For example, a frame with a start time 1234 secs after the scan start time would have a frame number of 124. N.B. Frame_num is not a frameset sequence number As a result of using a 10 sec bin, every 11th frame skips a number, so it is normal to see breaks in the frame numbering and it doesn't indicate missing data. Because frameset numbering is based on the predicted scan start time from the survey plan, and because frameset data may not start being acquired until well after the start of the scan, frameset numbers often do not start at 1 for a scan.
load_id	%3d	----	no	This is an internal archive accounting number that tracks in what batch of data the information in this record were loaded into the database.
cntr	%10d	----	no	Unique identification number for the Atlas Image Frame Cross Reference table entry created sequentially in the order of the Archive load processing.

Last Updated: 2011 April 26

Previous page Next page
Return to Explanatory Supplement TOC