KOA Glossary

General Archive Terms
Search Results
FITS Keywords
Additional Archive Metadata

General Archive Terms

caliblist: For each science file, KOA determines a set of calibration files that was taken with the same instrument configuration. Metadata describing these calibration files are recorded in a "caliblist" file which is named after the science file; these are available for browsing, and are also included in user-selected download packages.

Header Data Unit (HDU): A FITS file can be comprised of any number of "extensions," each of which can consist of a header and a data block. HIRES stores the readouts from each CCD on separate HDUs, each of which has their own set of keywords. Keywords that describe the entire FITS file are stored in the primary FITS extension, which contains no data block.

Metadata: A set of information that fully describes each data file in the archive. Metadata stored in the KOA database includes: FITS header keyword values (both those written by the telescope, and those added by the archive processing software); file location information; spatial coordinates and spatial bin assignments; proprietary period information; and certain transformations of original FITS keyword values (for instance, RA and DEC are stored as decimal values; the original FITS sexagesimal strings are kept in CRA and CDEC database columns).

Search Results

ASCII Table of Calibration Files: Click on this link to see the ASCII table containing a subset of the archive metadata for each displayed calibration file.

ASCII Table of Science Files: Click on this link to see the ASCII table containing the complete set of archive metadata for each displayed science file. All the header keywords from the primary FITS extension are represented as columns in this table; additional columns containing archive-specific metadata are also present. A complete description of the FITS keywords can be found at WMKO:

Associated Calibration Files: For each science file, KOA determines a set of calibration files that was taken with the same instrument configuration. (See: calibration association.) Clicking on the "caliblist" filename in this column will take you to a table of metadata describing all the associated calibration files. The "caliblist" is useful in determining which files to use when reducing this particular science file. Note: if there are no associated calibration files found for the science file, the caliblist will contain a table header but not data rows.

Date of Observation: Universal date of observation on which the exposure was begun, in the format YYYY-MM-DD.

DEC: Declination of the observed target, in sexagesimal DMS J2000 coordinates.

Exposure Time: Total exposure time. For NIRC2 and NIRSPEC, this is the exposure time per coadd multiplied by the number of coadds (ITIME x COADDS). Since December 2018, NIRSPEC's exposure time is TRUITIME x COADDS>.

FITS Keywords

A complete description of the FITS keywords can be found at WMKO:

Frame Number: For KPF, The frameno is incremented as an exposure count for the instrument over all time.

All other instruments: A number identifying the order in which FITS files were recorded during an observing run. The first exposure on a given night generally has a frame number of 1, but can be any number the observer chooses; thereafter, the frame number is automatically incremented for each exposure which the observer chooses to save to disk. Since the archive stores all exposures (not only those which the observer chooses to keep), it is possible for there to be several FITS files archived with the same frame number.

Image Type: KOAIMTYP describes the image type for the file.

For science files, the image type is "object." For calibration files, the image type can be any of the following: arclamp, bias, bias_lamp_on, dark, dark_lamp_on, eng calib, fcscal, flatlamp, flatlampoff, focus, polcal, trace, or undefined. For more information, see calibration types.

Iodine Cell: For HIRES, The iodine cell is used to create a reference wavelength in order to measure very precise radial velocities. This column specifies whether or not the iodine cell was in the light path during the observation, as determined from the IODIN and IODOUT keywords (i.e, if IODIN = F and IODOUT = T, then the iodine cell was not in the light path).

KOAID: Provides a link to download the FITS file directly. Note: clicking on this link will stream the FITS file to your browser, and may require you to have proprietary access to the requested FITS file. If you e-mail this link to a collaborator and any part of the FITS file is still proprietary, they will not be able to download the file without the appropriate username and password. The [TRS] link provides direct access to the TRS (Telemetry Recording System) data for that particular NIRC2 science file. Note that these files can be large (30--200 MB).

Program ID: A unique identifier assigned to each observing program when observing time is granted, and linked to a title and principal investigator. The same program ID may be used over muiltiple semesters.

Program Institution: Institution through which this observing program was proposed.

Program PI: The last name (and sometimes the first initial) of the observing program's principal investigator.

Program Title: Title given to the observing program.

Quicklook Previews: [Hdr] All instruments - will display the FITS header.

[Raw] All instruments - will display JPEG previews of the uncalibrated images when available.

[Lev1], [Lev2], or [Lev1 Lev2] DEIMOS, KCWI, MOSFIRE, and OSIRIS - will return a page with all of the Level 1 (quicklook) and/or Level 2 (science ready) reduced data products.

[Calibrated] NIRC2 - will show the calibrated image when available.

[Extracted] HIRES - will show GIF previews and interactive plot of the extracted spectra when available (browse product only - see HIRES Extracted Specra Visualization).

[Reduced] LWS - will show a two-dimensional coadded image converted from the raw 6-dimensional frame of chop-nod beams when available.

[Reduced] OSIRIS - will show an image of the reduced data cube when available.

RA: Right ascension of the observed target, in sexagesimal HMS J2000 coordinates.

Readout Quality: (HIRES only) Quality of the electronics readout of the FITS file. When the HIRES mosaic was commissioned in August 2004, it was found to display an electronics readout problem that appeared as "glitches," or abrupt jumps in baseline levels, in the data signal. A solution was found, and this problem was corrected. However, it was still possible to get "glitched" images on extremely over-exposed frames. When a "glitch" is found, the keyword ROQUAL is assigned a value of "bad." When a FITS file with a ROQUAL of "bad" is displayed in the archive, its row is highlighted orange.

Target Name: The name of the observed target, as recorded from the observer's target list at the time of observation.

Time of Observation: Coordinated universal time at the start of the exposure. Occasionally, DATE-OBS and UTC keyword values, showing the time that the data were taken, are missing from the original FITS files. A relatively small number of NIRSPEC files, mostly afternoon calibration files, are affected by this. For these cases, the KOA software has attempted to recreate values, but they are estimates only, and may be highly inaccurate in the case of UTC. You can identify these recreated UTC values by the comment line in the FITS header. Recreated values of UTC or DATE-OBS have the comment: "Original value missing - added by KOA"

Wavelength Range: The approximate blue or red wavelength in angstroms or microns (GUIDER). These wavelengths are determined by the KOA software, using details of the instrument setup such as grating angles, filters etc.

Not available for LWS or NIRC.

Archive Metadata

The following columns can be found in the ASCII tables of science and calibration files, but are not part of the FITS headers:

DEC: Decimal conversion of DEC FITS keyword

FILEHAND: Used by archive software to retrieve the FITS file.

FILEURL: URL of the FITS file (if URL-accessible; proprietary data can not be retrieved directly via URL)

KOAIMTYP: KOAIMTYP describes the image type for the file.

For science files, the image type is "object." For calibration files, the image type can be any of the following: arclamp, bias, bias_lamp_on, dark, dark_lamp_on, eng calib, fcscal, flatlamp, flatlampoff, focus, polcal, trace, or undefined. For more information, see calibration types.

INSTRUMENT: The results values are fixed to the name of the Instrument: DEIMOS, ESI, GUIDER, HIRES, KCWI, KPF, LRIS, LWS, MOSFIRE, NIRC, NIRC2, NIRES, NIRSPEC, OSIRIS.

FITS header keywords for instrument:
INSTRUME: DEIMOS, ESI, HIRES, KCWI, KPF, LRIS, LWS, MOSFIRE, NIRC, NIRC2, NIRES, NIRSPEC, OSIRIS

CURRINST: GUIDER

PROPN: Indicates whether or not detector #N is proprietary (ie, currently only retrievable by the PI associated with this FITS file). If "t," any HDUs representing that CCD will be blank when the file is downloaded. Only files with at least 1 available CCD are displayed to the user.

PROPINT: The proprietary period in units of months.

RA: Decimal conversion of RA FITS keyword

SEMID: Built from the keywords SEMESTER and PROGID, SEMID is a unique program identifier across all semesters.

Please acknowledge the use of KOA by including this text in your publications:

This research has made use of the Keck Observatory Archive (KOA), which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute (NExScI), under contract with the National Aeronautics and Space Administration.

Please also acknowledge the PI(s) of datasets that have been obtained through KOA, and please contact the KOA Help Desk if you publish archival data.

If your research uses data reduced by the DEIMOS DRP or MOSFIRE DRP, please use the PypeIt Citation.

The Keck Observatory Archive (KOA) is a collaboration between the NASA Exoplanet Science Institute (NExScI) and the W. M. Keck Observatory (WMKO). NExScI is sponsored by NASA's Exoplanet Exploration Program, and operated by the California Institute of Technology in coordination with the Jet Propulsion Laboratory (JPL).

\#koashare.html\

+ Getting Started + KOA Search Form + KOA and Python + KI Search Form + Publicly Available Data + Contributed Datasets + KOA User Guide + Image API + Reducing Keck Data + KOA Helpdesk + KOA News + Related Archives + Login / Logout	KOA Glossary General Archive Terms Search Results FITS Keywords Additional Archive Metadata General Archive Terms caliblist: For each science file, KOA determines a set of calibration files that was taken with the same instrument configuration. Metadata describing these calibration files are recorded in a "caliblist" file which is named after the science file; these are available for browsing, and are also included in user-selected download packages. Header Data Unit (HDU): A FITS file can be comprised of any number of "extensions," each of which can consist of a header and a data block. HIRES stores the readouts from each CCD on separate HDUs, each of which has their own set of keywords. Keywords that describe the entire FITS file are stored in the primary FITS extension, which contains no data block. Metadata: A set of information that fully describes each data file in the archive. Metadata stored in the KOA database includes: FITS header keyword values (both those written by the telescope, and those added by the archive processing software); file location information; spatial coordinates and spatial bin assignments; proprietary period information; and certain transformations of original FITS keyword values (for instance, RA and DEC are stored as decimal values; the original FITS sexagesimal strings are kept in CRA and CDEC database columns). Search Results ASCII Table of Calibration Files: Click on this link to see the ASCII table containing a subset of the archive metadata for each displayed calibration file. ASCII Table of Science Files: Click on this link to see the ASCII table containing the complete set of archive metadata for each displayed science file. All the header keywords from the primary FITS extension are represented as columns in this table; additional columns containing archive-specific metadata are also present. A complete description of the FITS keywords can be found at WMKO: DEIMOS keywords ESI keywords HIRES keywords KCWI keywords LRIS keywords LWS keywords MOSFIRE keywords NIRC keywords NIRC2 keywords NIRSPEC keywords OSIRIS keywords Associated Calibration Files: For each science file, KOA determines a set of calibration files that was taken with the same instrument configuration. (See: calibration association.) Clicking on the "caliblist" filename in this column will take you to a table of metadata describing all the associated calibration files. The "caliblist" is useful in determining which files to use when reducing this particular science file. Note: if there are no associated calibration files found for the science file, the caliblist will contain a table header but not data rows. Date of Observation: Universal date of observation on which the exposure was begun, in the format YYYY-MM-DD. DEC: Declination of the observed target, in sexagesimal DMS J2000 coordinates. Exposure Time: Total exposure time. For NIRC2 and NIRSPEC, this is the exposure time per coadd multiplied by the number of coadds (`ITIME` x `COADDS`). Since December 2018, NIRSPEC's exposure time is `TRUITIME` x `COADDS`>. FITS Keywords A complete description of the FITS keywords can be found at WMKO: DEIMOS keywords ESI keywords HIRES keywords KCWI keywords LRIS keywords LWS keywords MOSFIRE keywords NIRC keywords NIRC2 keywords NIRSPEC keywords OSIRIS keywords Frame Number: For KPF, The frameno is incremented as an exposure count for the instrument over all time. All other instruments: A number identifying the order in which FITS files were recorded during an observing run. The first exposure on a given night generally has a frame number of 1, but can be any number the observer chooses; thereafter, the frame number is automatically incremented for each exposure which the observer chooses to save to disk. Since the archive stores all exposures (not only those which the observer chooses to keep), it is possible for there to be several FITS files archived with the same frame number. Image Type: `KOAIMTYP` describes the image type for the file. For science files, the image type is "object." For calibration files, the image type can be any of the following: arclamp, bias, bias_lamp_on, dark, dark_lamp_on, eng calib, fcscal, flatlamp, flatlampoff, focus, polcal, trace, or undefined. For more information, see calibration types. Iodine Cell: For HIRES, The iodine cell is used to create a reference wavelength in order to measure very precise radial velocities. This column specifies whether or not the iodine cell was in the light path during the observation, as determined from the `IODIN` and `IODOUT` keywords (i.e, if `IODIN = F` and `IODOUT = T`, then the iodine cell was not in the light path). KOAID: Provides a link to download the FITS file directly. Note: clicking on this link will stream the FITS file to your browser, and may require you to have proprietary access to the requested FITS file. If you e-mail this link to a collaborator and any part of the FITS file is still proprietary, they will not be able to download the file without the appropriate username and password. The [TRS] link provides direct access to the TRS (Telemetry Recording System) data for that particular NIRC2 science file. Note that these files can be large (30--200 MB). Program ID: A unique identifier assigned to each observing program when observing time is granted, and linked to a title and principal investigator. The same program ID may be used over muiltiple semesters. Program Institution: Institution through which this observing program was proposed. Program PI: The last name (and sometimes the first initial) of the observing program's principal investigator. Program Title: Title given to the observing program. Quicklook Previews: `[Hdr]` All instruments - will display the FITS header. `[Raw]` All instruments - will display JPEG previews of the uncalibrated images when available. `[Lev1], [Lev2], or [Lev1 Lev2]` DEIMOS, KCWI, MOSFIRE, and OSIRIS - will return a page with all of the Level 1 (quicklook) and/or Level 2 (science ready) reduced data products. `[Calibrated]` NIRC2 - will show the calibrated image when available. `[Extracted]` HIRES - will show GIF previews and interactive plot of the extracted spectra when available (browse product only - see HIRES Extracted Specra Visualization). `[Reduced]` LWS - will show a two-dimensional coadded image converted from the raw 6-dimensional frame of chop-nod beams when available. `[Reduced]` OSIRIS - will show an image of the reduced data cube when available. RA: Right ascension of the observed target, in sexagesimal HMS J2000 coordinates. Readout Quality: (HIRES only) Quality of the electronics readout of the FITS file. When the HIRES mosaic was commissioned in August 2004, it was found to display an electronics readout problem that appeared as "glitches," or abrupt jumps in baseline levels, in the data signal. A solution was found, and this problem was corrected. However, it was still possible to get "glitched" images on extremely over-exposed frames. When a "glitch" is found, the keyword `ROQUAL` is assigned a value of "bad." When a FITS file with a `ROQUAL` of "bad" is displayed in the archive, its row is highlighted orange. Target Name: The name of the observed target, as recorded from the observer's target list at the time of observation. Time of Observation: Coordinated universal time at the start of the exposure. Occasionally, DATE-OBS and UTC keyword values, showing the time that the data were taken, are missing from the original FITS files. A relatively small number of NIRSPEC files, mostly afternoon calibration files, are affected by this. For these cases, the KOA software has attempted to recreate values, but they are estimates only, and may be highly inaccurate in the case of UTC. You can identify these recreated UTC values by the comment line in the FITS header. Recreated values of UTC or DATE-OBS have the comment: "Original value missing - added by KOA" Wavelength Range: The approximate blue or red wavelength in angstroms or microns (GUIDER). These wavelengths are determined by the KOA software, using details of the instrument setup such as grating angles, filters etc. Not available for LWS or NIRC. Archive Metadata The following columns can be found in the ASCII tables of science and calibration files, but are not part of the FITS headers: DEC: Decimal conversion of DEC FITS keyword FILEHAND: Used by archive software to retrieve the FITS file. FILEURL: URL of the FITS file (if URL-accessible; proprietary data can not be retrieved directly via URL) KOAIMTYP: `KOAIMTYP` describes the image type for the file. For science files, the image type is "object." For calibration files, the image type can be any of the following: arclamp, bias, bias_lamp_on, dark, dark_lamp_on, eng calib, fcscal, flatlamp, flatlampoff, focus, polcal, trace, or undefined. For more information, see calibration types. INSTRUMENT: The results values are fixed to the name of the Instrument: DEIMOS, ESI, GUIDER, HIRES, KCWI, KPF, LRIS, LWS, MOSFIRE, NIRC, NIRC2, NIRES, NIRSPEC, OSIRIS. FITS header keywords for instrument: `INSTRUME`: DEIMOS, ESI, HIRES, KCWI, KPF, LRIS, LWS, MOSFIRE, NIRC, NIRC2, NIRES, NIRSPEC, OSIRIS `CURRINST`: GUIDER PROPN: Indicates whether or not detector #N is proprietary (ie, currently only retrievable by the PI associated with this FITS file). If "t," any HDUs representing that CCD will be blank when the file is downloaded. Only files with at least 1 available CCD are displayed to the user. PROPINT: The proprietary period in units of months. RA: Decimal conversion of RA FITS keyword SEMID: Built from the keywords `SEMESTER` and `PROGID`, `SEMID` is a unique program identifier across all semesters.

Please acknowledge the use of KOA by including this text in your publications: This research has made use of the Keck Observatory Archive (KOA), which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute (NExScI), under contract with the National Aeronautics and Space Administration. Please also acknowledge the PI(s) of datasets that have been obtained through KOA, and please contact the KOA Help Desk if you publish archival data. If your research uses data reduced by the DEIMOS DRP or MOSFIRE DRP, please use the PypeIt Citation. Privacy Policy Image Use Policy The Keck Observatory Archive (KOA) is a collaboration between the NASA Exoplanet Science Institute (NExScI) and the W. M. Keck Observatory (WMKO). NExScI is sponsored by NASA's Exoplanet Exploration Program, and operated by the California Institute of Technology in coordination with the Jet Propulsion Laboratory (JPL). KOA WMKO \#koashare.html\