Below, we briefly describe the contents of the DEEP2 “bintabs” files, which detail the design parameters for each DEIMOS slitmask in 8 separate binary tables:
(1) ObjectCat
(2) MaskDesign
(3) DesiSlits
(4) SlitObjMap
(5) MaskBlu
(6) BluSlits
(7) Observers
(8) PhotCat
To download the bintabs files or learn more about linking the various tables, refer to the bintabs primer.
In IDL, the various binary tables can be read in like so:
IDL> objcat = mrdfits(‘1243.bintabs.fits.gz’, 1)
where the second argument (“1”) specifies the particular binary table (the first — i.e. ObjectCat). To list the contents of a “bintabs” file (e.g. to confirm ordering of the tables), the fits_info.pro and fits_help.pro routines can be employed.
ObjectCat
The ObjectCat table gives info about the objects targeted on the slitmask:
| Catalog Tag | Data Type | Brief Description |
| OBJECTID | LONG | an object ID number assigned by the DEIMOS slitmask software (i.e. not the DEEP2 8-digit objno). This tag is useful for linking this table to other tables in the “bintabs” file, such as the SlitObjMap. |
| OBJECT | STRING | the 8-digit DEEP2 ID number as assigned in the photometry catalogs (or “pcats”) |
| RA_OBJ | DOUBLE | Right Ascension (in decimal degrees) for the object |
| DEC_OBJ | DOUBLE | Declination (in decimal degrees) for the object |
| RADECSYS | STRING | the RA/Dec system used (FK5) |
| EQUINOX | DOUBLE | the reference epoch for the RA/Dec system (J2000) |
| MJD_OBS | DOUBLE | MJD at the time of observation (not used) |
| MAG | FLOAT | the object’s R-band magnitude in the DEEP2 pcats |
| PBAND | STRING | the passband correspond to the magnitude value (always CFHT R band) |
| RADVEL | DOUBLE | radial velocity of target (not used) |
| MAJAXIS | FLOAT | major axis size in arcseconds (not set) |
| OBJCLASS | STRING | identifies the object (or slit) as being assigned to one of the following clases: Program_Target (i.e. a science target) Alignment_Star (i.e. an alignment star) Note that DEEP2 uses sky-only slits, in which no object is position. These slits are still listed as Program_Targets, but they can be identified based on the narrower slit widths (0.7” versus 1”). |
MaskDesign
The MaskDesign table gives general info about the DEIMOS slitmask:
| Catalog Tag | Data Type | Brief Description |
| DESID | LONG | an ID number assigned to the slitmask design |
| DESNAME | STRING | a name given to the design (typically DEEP2.1HS. plus the 4-digit slitmask #) |
| DESPID | LONG | not used |
| DESCREAT | STRING | the person and software responsible for mask creation |
| DESDATE | STRING | he date on which the mask was signed (i.e. submitted to the DEIMOS slitmask database/milling system) |
| DESNSLIT | LONG | the number of slitlets on the mask |
| DESNOBJ | LONG | the number of objects in the source catalog that fall on the slitmask — though, not necessarily assigned a slit |
| PROJNAME | STRING | the name of the project (i.e. DEEP2) |
| INSTRUME | STRING | the instrument used (i.e. DEIMOS) |
| MASKTYPE | STRING | unique ID identifying type of slitmask (not used) |
| RA_PNT | DOUBLE | Right Ascension of the telescope pointing axis |
| DEC_PNT | DOUBLE | Declination of the telescope pointing axis |
| RADEPNT | STRING | the RA/Dec system used (e.g. FK5) |
| EQUIPNT | FLOAT | the reference epoch for the RA/Dec |
| PA_PNT | DOUBLE | the position angle (E of N in degrees) of the mask on the sky |
| DATE_PNT | STRING | the anticipated date that the slitmask will be observed |
| LST_PNT | FLOAT | the anticipated local sidereal time of observation |
| UID | INT | ID code for Keck slitmask database |
| STAMP | STRING | timestamp corresponding to submission to the Keck database |
DesiSlits
The DesiSlits table gives useful info about each of the slitlets on the DEIMOS slitmask:
| Catalog Tag | Date Type | Brief Description |
| DSLITID | LONG | an id number assigned to the slit — again, this is useful for linking this table with others such as the ObjectCat (i.e. allowing for matching of objects to their slitlets). |
| DESID | LONG | not id number assigned to the slitmask |
| SLITRA | DOUBLE | the RA of the slits |
| SLITDEC | DOUBLE | the Dec of the slits |
| SLITTYP | STRING | the type of slit: ‘P’ for porgram target and ‘A’ for alignment star. |
| SLITLEN | FLOAT | the length of the slit in arcseconds |
| SLITLPA | FLOAT | the slit PA (E of N in deg) — note that this is given in absolute terms and NOT relative to the PA of the mask |
| SLITWID | FLOAT | the width of the slit in arcseconds |
| SLITWPA | FLOAT | projected PA of the slit width on the sky (not used) |
| SLITNAME | STRING | the slit # (the same # as used by the DEEP2 spec2d reduction code and given in the filenames for the DR4 |
SlitObjMap
The SlitObjMap table gives more useful info for each slitlet on the slitmask and is the key to linking the other tables to each other:
| Catalog Tag | Data Type | Brief Description |
| DESID | LONG | ID number assigned to the slitmask |
| OBJECTID | LONG | the DEEP2 8-digit object ID number (as also given in the ObjectCat) |
| DSLITID | LONG | an id number assigned to the slit |
| TOPDIST | FLOAT | the distance from the targeted object to the top end of the slitlet (in arcseconds) |
| BOTDIST | FLOAT | same as TOPDIST, but from the opposite end of the slitlet |
MaskBlu
The MaskBlu table gives general info about the DEIMOS slitmask design and milling:
| Catalog Tag | Data Type | Brief Description |
| BLUID | LONG | the ID number assigned to the slitmask design |
| DESID | LONG | a different ID number (see MaskDesign table) |
| BLUNAME | STRING | a name given to the design (typically DEEP2.1HS. plus the 4-digit slitmask number) |
| BLUPID | LONG | not used |
| BLUCREAT | STRING | the software used to create the mask design |
| BLUEDATE | STRING | the date on which the mask design was submitted |
| LST_USE | LONG | the local sideral time during planned observations |
| DATE_USE | STRING | the date of planned observations |
| TABLEID | LONG | a telescope id number |
| REFID | LONG | not used |
| ATMTEMPC | FLOAT | various atmospheric properties assumed in designing and milling the mask… |
| ATMPRES | FLOAT | |
| ATMHUMID | FLOAT | |
| ATMTLAP | FLOAT | |
| REFWAVE | FLOAT | |
| DISTID | LONG | not used |
| GUINAME | STRING | the name that the slitmask was given within the milling system and on the DEIMOS dashboard GUI |
| MILLSEQ | STRING | empty |
| STATUS | INT | not used |
| LOC | STRING | empty |
| STAMP | STRING | a timestamp corresponding to the design date |
BluSlits
The BluSlits table gives info about the position of the slitlets on the DEIMOS slitmask:
| Catalog Tag | Data Type | Brief Description |
| BSLITID | LONG | the ID number assigned to the slitmask design |
| BLUID | LONG | a different ID number (see MaskBlu table) |
| DSLITID | LONG | a name given to the design (typically DEEP2.1HS. plus the 4-digit slitmask number) |
| SLITX1 | DOUBLE | the positions of the 4 corners of each slitlet in the x- and y-directions… |
| SLITY1 | DOUBLE | |
| SLITX2 | DOUBLE | |
| SLITY2 | DOUBLE | |
| SLITX3 | DOUBLE | |
| SLITY3 | DOUBLE | |
| SLITX4 | DOUBLE | |
| SLITY4 | DOUBLE | |
| BAD | LONG |
Observers
The Observers table gives reference info for the observer/designer of the slitmask.
PhotCat
The PhotCat table gives info from the DEEP2 photometry catalog. The tags are explained in the DR4 photometry primer.