KOA Glossary

General Archive Terms

caliblist: For each science file, the KOA generates an ASCII metadata table describing all its associated calibration files, and given a ".caliblist" extension.

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).

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KOAID: A unique file name assigned by the archive software to each FITS file. Each filename is in the form HI.YYYYMMDD.#####, where HI denotes the instrument name (i.e., HIRES), YYYYMMDD is the UT date of observation (from the DATE-OBS keyword in the FITS header), and ##### is the UTC time (in seconds) at which the exposure was taken (from the UTC keyword). When the KOAID column contsains an active link, clicking on it will initiate a download of that FITS file. Selecting the checkbox to the left of the KOAID will add the FITS file to your download selection list.

CCD Previews: HIRES is comprised of 3 CCDs; each HDU in the FITS file contains data from only one of the CCDs. (Which CCD can be determined from the CCDLOC keyword.) For each HDU, a JPEG preview is generated; this column contains links to any available JPEG images.

Associated Calibration Files: 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.

Frame Number: [FITS keyword: FRAMENO] The frame number of the FITS file, as assigned by the observer. The first exposure taken genereally has a frame number of 1, but can be any number the observer chooses; thereafter, the frame number is incremented for each exposure. Since the archive stores all frames (not only those which the observer chooses to save), it is possible for there to be several FITS files archived with the same frame number.

Available CCDs: Each HIRES CCD mosaic consists of 3 individual CCDs, each of which can have a different proprietary period. This column shows the number of CCDs which are currently available to the user for download. For Deep Impact data, the entire mosaic is public from the date of observation.

Target Name: [FITS keyword: TARGNAME, or OBJECT (if TARGNAME is blank)] The name of the observed target, as found in the observer's target list.

RA: [FITS keyword: RA] Right ascension of the observed target, in J2000 coordinates

DEC: [FITS keyword: DEC] Declination of the observed target, in J2000 coordinates

Date of Observation: [FITS keyword: DATE-OBS] Universal date of observation, in the format YYYY-MM-DD.

Time of Observation: [FITS keywords: UT, UTC] Coordinated universal time at the start of the exposure.

Exposure Time: [FITS keyword: ELAPTIME] Actual exposure time, rounded to the nearest second. (TTIME keyword contains the exposure time requested by the observer; EXPTIME keyword contains the time in seconds from shutter open to shutter close, and is a real number.)

Image Type: [FITS keyword: IMAGETYP] For science files, the image type is "object." For calibration files, the image type can be any of the following: bias, dark, arclamp, flatlamp, focus, or trace.

Wavelength Range: [FITS keywords: WAVEBLUE, WAVERED] The approximate wavelength range (in Angstroms) for the observed spectrum. The short wavelength is the central wavelength of the bluest order (WAVEBLUE), and the long wavelength is the central wavelength of the reddest order (WAVERED). These wavelengths are determined by the KOA software, using the ehcelle and cross-disperser angles (found in the ECHANGL and XDANGL keywords).

Iodine Cell: [FITS keywords: IODIN, IODOUT] The iodine cell is used to create a reference wavelgnth 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).

Program ID: [FITS keyword: PROGID] Unique identifier assigned to each observing program when observing time is granted.

Program Institution:[FITS keyword: PROGINST] Institution of the principal investigator for this observing program.

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

Program Title: [FITS keyword: PROGTITL] Title given to the observing program.

Readout Quality: [FITS keyword: ROQUAL] 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 red.

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's HIRES keywords page.

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.

FITS Keywords

A complete description of the FITS keywords can be found at WMKO's HIRES keywords page.

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:

PROPN: Whether or not CCD #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.

PROPMIN: The shortest of the three possible proprietary periods (one per CCD), in interval notation: DD HH:MM:SS.

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

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)

RA: Decimal conversion of RA FITS keyword

DEC: Decimal conversion of DEC FITS keyword

CRA: Copy of original sexagesimal coordinate string in RA keyword

CDEC:Copy of original sexagesimal coordinate string in DEC keyword

Please contact KOA Support with questions or problems.