Pipeline Data Guide
3. Spectral Data Product Files
5. Primary Object Catalog - Merged FUV+NUV Catalog (mcat file)
1. Pipeline Overview
The GALEX data pipeline converts GALEX satellite telemetry data and any necessary corollary data into calibrated images and catalogs. The GALEX Science Operations Center (SOC) receives data from the satellite and ingestpipe unpacks it into time-tagged photon lists, instrument/SC housekeeping and satellite aspect information. From these data sets, orbpipe generates images, spectra and source catalogs.
Astrometric modules rta (for rectify, transform and aspect) and deltaphot correct the photon positions for detector and optical distortions and determines an aspect solution using star positions from the time-tagged photon data. The astrometric refinement process is diagrammed below.
A photometric module simplemap accumulates the photons into count and intensity maps and sextra extracts sources from images. A spectroscopic module galexspac uses image source catalog inputs to extract spectra of these sources from the multiple slitless grism observations.
2. Pipeline Products
Data from each single-orbit visit stored in a single directory in the GALEX file system. The directory path has the following format:
<ROOT>/<proc ver>/<tile>/<obs mode>/<product>/<image>/<try>/.
An example path and filename is:
Path: <root>/01-vsn/10330-AISCHV2_381_40554/d/00-visits/0002-img/03-try/
Filename: AISCHV2_381_40554_0002_sv12-xd-mcat.fits
This path contains the pipeline processing version number, a tile identification string, instrument observing mode (direct, grism, opaque; represented by d, g, o, in each case preceded by the wavelength, data product type (single visit, multiple visit), and the pipeline processing try. Additionally, a unique source ID tag is be generated by the pipeline which uniquely encodes both the path information and the source number from merged source and spectra catalogs.
All of the pipeline products are described in the table below.
Table 3.1 Pipeline Products Summary
Filename Suffix |
File type |
Description |
Low-level pipeline products |
Photon and housekeeping files |
|
-asp.rec |
Binary record |
Satellite attitude solution |
-asprta.rec |
Binary record |
Refined attitude solution |
-rtastar.fits |
FITS binary table |
Star catalog for attitude refinement |
-scst.fits |
FITS binary table |
Spacecraft state file |
-nd-dphcent.txt |
ASCII record |
Deltaphot attitude output |
-nd-dph.fits |
FITS binary table |
Deltaphot photon delta output |
-[n or f]d-raw6.fits |
FITS binary table |
Raw photon data |
-[n or f]d-x.fits |
FITS binary table |
Extended photon record |
Images |
Maps and associated files |
|
-[n or f]d-cnt.fits |
FITS image |
Count map (J2000) |
-[n or f]d-dose.fits |
FITS image |
Dose map (detector frame) |
-[n or f]d-exp.fits |
FITS image |
Exposure map (J2000) |
-[n or f]d-intbgsub.fits |
FITS image |
Background subtracted intensity map (J2000) |
-[n or f]d-int.fits |
FITS image |
Intensity map (J2000) |
-[n or f]d-movie.fits |
FITS image cube |
Time-slice count maps (J2000) |
-[n|f]d-rr.fits |
FITS image |
low res relative response (J2000) |
-[n or f]d-rrhr.fits |
FITS image |
high-res relative response (J2000) |
-[n or f]d-skybg.fits |
FITS image |
sky background image (J2000) |
-[n or f]d-wt.fits |
FITS image |
weight/mask image (J2000) |
Catalogs |
FUV, NUV and merged catalogs |
|
-[n or f]d-cat.fits |
FITS binary table |
Sextractor catalogs for images |
-fd-ncat.fits |
FITS binary table |
FUV extractions using NUV positions |
-nd-fcat.fits |
FITS binary table |
NUV extractions using FUV positions |
-xd-mcat.fits |
FITS binary table |
Merged source catalog |
Flags |
Artifact flag information |
|
-[n or f]d-flags.fits |
FITS image |
Artifact Flag image (J2000) |
-[n or f]d-flagstar.fits |
FITS binary table |
Star catalog for flagging |
-[n or f]d-flag_bright.ds9reg |
ds9 Region file |
Bright star flag regions |
-[n or f]d-flag_dichroic.ds9reg |
ds9 Region file |
Dichroic reflection flag regions |
-[n or f]d-flag_edge.ds9reg |
ds9 Region file |
Edge flag regions |
-[n or f]d-flag_near.ds9reg |
ds9 Region file |
Near bright star flag regions |
-[n or f]d-flag_window.ds9reg |
ds9 Region file |
Window reflection regions |
Grism-specific files |
||
-[n or f]g-gsax.fits |
FITS binary table |
Spectral extraction parameter information for each source |
-[n or f]g-pri.fits |
FITS binary table |
Image strips for each source from a single visit |
-[n or f]g-prc.fits |
FITS binary table |
Image strips (combined) for each source from multiple visits |
-[n or f]g-prm.fits |
FITS binary table |
Image strips (median) for each source from multiple visits |
-[n or f]g-gsp.fits |
FITS binary table |
Spectral data for each extracted source vs. wavelength |
-xg-gsp.fits |
FITS binary table |
Spectral data for each extracted source vs.wavelength (both bands) |
-[n or f]g-xsp.fits |
FITS binary table |
Spectral data for each extracted source vs. offset |
3. Spectral Data Product Files
The spectral data product files are stored in binary FITS format, but they are GALEX-specific. The formats of these files is described below:
-pri.fits (not included in ERO release)
This file contains the image strips for individual exposures for each spectral-extracted source. The photon data, response, and masking
images are recorded for each source. Masking for the image strip is stored in the response image (neighbor masking) and the
photon data image (other masking) as negative numbers. Spectral response variations with position (column) are stored in the response
image in the final row. These images contain the total accumulated photon data for each source for a given single visit or exposure.
Each source has its own FITS header unit. The order of the image strips is identical to the order of sources in the extracted source catalog given
in the (root)-gsax.fits file.
First Header Unit: Grism angle used for these extractions, total exposure time, total number of spectrally extracted sources (ECOUNT),
field center, and other extraction parameters.
Second through “N" Header Unit: Accumulated image strips for photon data and response for any of N-1 sources in the field of view.
The header portion defines the image dimensions (PRI_NC,PRI_NR). The scale is given in arcseconds per pixel in both spatial and dispersion
directions. The header key words also include the blue limit offset in arcseconds (ARCSEC1) relative to the object center (undeviated) position,
which is used to derive the wavelength scale. The image strips typically cover multiple grism orders, e.g. 1st, 2nd, and 0th. The image data is
stored as 2-byte integers, which can be scaled to true data values using the header key words DATZERO, DATSCALE, RSPZERO, and RSPSCALE.
-prc.fits
This file contains the combined or summed image strips for multiple exposures for each spectral-extracted source. The format is the same as
for the pri files, except that masking has been applied before summing. That is, all masked pixels in the individual (pri) image strips were
set to zero before summing.
First Header Unit: Contains the filenames of all *-pri.fits which have been combined, as well as their respective grism angles.
Second through ”N” Header Unit: Accumulated image strips for photon data and response for any of N-1 sources in the field of view.
-prm.fits
This file contains the medianed image strips for multiple exposures for each spectral-extracted source. The format is the same as for the pri files, except that masked pixels have been ignored by the median value calculation.
First Header Unit: Contains the filenames of all *-pri.fits which have been medianed, as well as their respective grism angles.
Second through “N” Header Unit: Accumulated image strips for photon data and response for any of N-1 sources in the field of view.
-gsax.fits
General information (binary FITS table). This file contains parameter information, as well as a source list table including extraction
parameters for each source. This source list catalog is created on the first exposure and read in and used for each subsequent exposure. This
file also contains a table of data for each accumulated exposure.
First Header Unit: Header key words contain various extraction parameters for ``galaxspac" (spectral accumulation program). These
include the flux cutoff (i.e., the brightest ``N" sources) used on the direct image source catalog, the field RA,Dec origin, the masking parameters,
band number, the total number of exposures (or orbits) and exposure time accumulated.
Second Header Unit: Extracted source list. This contains a source catalog of all the sources which have been extracted. This
includes the RA,Dec positions, global IDs, direct image FUV and NUV flux rates, direct image FWHMs, and extraction parameters (object and
background widths and length of the spectrum) for each source.
Third Header Unit: Accumulated exposures (orbits) list. This contains a catalog of all the photon data sets added into the image
strips. This includes all the *-pri.fits filenames, grism angles, field offsets used (x, y, twist (rotation) relative to the direct image source
positions), exposure times, and reduction dates.
-xsp.fits
An xsp file, labeled *-fg-xsp and *-ng-xsp, is extracted for each wavelength band. Each file represents two sequential spectral orders as recorded along the spectral axis on the detector, so units are photons per second per arcsecond. Each source has its own FITS header unit, in the same order as the data occur in the -pri.fits file.
First Header Unit: Contains the header key word for the total number of sources extracted (ECOUNT).
Second through ``N" Header Unit: Spectra for each source and its computed 1 sigma error. Spectra are given in photons/second/pixel vs.
offset arcsecond (position relative to object center or undeviated object position).
-gsp.fits
There are three gsp files for each spectrum: *-fg-gsp, *-ng-gsp, and *-xg-gsp. The first two are grism-order combined (m =1 and 2 for NUV, and 2 and 3 for FUV), flux calibrated, and rebinned onto a linear wavelength scale. The third is the conjoined spectrum of the first two. The units for these are photons s-1 cm-2 Angstrom-1. The fg-gsp and ng-gsp files are for many purposes rendered obsolete by the xg-gsp file. Since the dispersion is linear, the zero point and dispersion of the wavelength scale are given as table entries. Two of the vector entries (flux and error) are for a simple (summation) extraction, and two vectors are for the optimal extraction.
Each file consists of a short primary header (giving the number of spectra in the file) and a single extension. In this extension each row gives spectral information (default fluxes, associated errors, optimally extracted fluxes, associated errors) for an astronomical object. These rows are listed in order of their appearance in the extracted source catalog in the (root)-gsax.fits file. However, ”masked” sources appearing in the gsax file are not extracted as spectra and thus not included in the gsp file listing.
4. Source Extraction
For source extraction, the GALEX pipeline utilizes the program SExtractor (Bertin & Arnouts 1996) for detection and photometry of sources in the GALEX imaging data. A general description of SExtractor is given in Bertin & Arnouts (1996) as well as in the Sextractor manual (Available from http://terapix.iap.fr/soft/sextractor/). Another useful reference is the ``SExtractor for Dummies'' manual written by Benne Holwerda {Available from his web site http://www-int.stsci.edu/~holwerda/SE/}. The pipeline includes a module poissonbg which computes a background map for each image as well as a corresponding detection threshold image. Typical backgrounds in high Galactic latitude GALEX fields are ~103 and 104 photons s-1 arcsec-2 in the FUV and NUV bands, respectively. With such low count rates, the distribution of count rates in each image is typically quite non-Gaussian, even for relatively long exposures. In order to deal with these low backgrounds, uses a modified clipping algorithm which makes use of the full Poisson distribution.
When running SExtractor, we use two images as input: one for detection and the second for photometry. For the detection image we use the ratio of the background-subtracted data image to the detection threshold map. All pixels in this ratio map which rise above the detection threshold will have values greater than one and we have therefore set the parameters in SExtractor so that it will consider all of these pixels as possibledetections. The image used for photometry is simply the background subtracted data image. Since we subtract the background from the data before running SExtractor, the background value within SExtractor is explicitly set to zero. As a result, the error estimates computed by Sextractor do not include the uncertainty due to the background counts. In the FUV-NUV merged catalog, we have updated the magnitude and flux errors to account for the background counts. (These are the fields called NUV_MAGERR, NUV_FLUXERR, FUV_MAGERR and FUV_FLUXERR in the merged catalog). These fluxes and errors refer to the Kron magnitudes measured by SExtractor and are computed as follows:
where f is the flux from the source in counts/sec, s is the sky level in counts/sec/pixel, is the area over which the flux is measured
( 
for the Kron flux) and t is the effective exposure time in seconds. Then the corresponding magnitude error is
.
SExtractor makes a few different measurements of the total flux of a source. For resolved sources, the MAG_AUTO measurement is probably the most appropriate choice while MAG_APER would be better suited for measurements of unresolved sources. Despite its name, MAG_BEST is not necessarily the best choice for most applications since the measurement for all objects are not made in a consistent way.
5. Primary Object Catalog - Merged FUV+NUV Catalog (mcat file)
The merged object catalog is the final catalog product from the GALEX data pipeline. It contains the full complement of source extractions from both the FUV and NUV images. The columns of the mcat file fall into the following major categories:
· Observation description
o Contains global object ID, pipeline version, image tile number, observation type, optics wheel position, image product type, pipeline re-run (try) number, band, mcat ID, subvisit number and leg number (where applicable)
· Band merger output quantities and flags
o Includes merged position in Equatorial and Galactic coordinates, extinction E(B-V) from Schlegel maps, and calibrated fluxes, magnitudes and errors. “Calibrated”currently means that values have been converted to AB magnitudes. Four additional columns contain FUV fluxes extracted at NUV detection positions, NUV fluxes extracted at FUV detection positions and their errors. These are useful for any study that is best performed using identical aperture photometry in each band (e.g. for colors, photometric redshifts)
· Neighbor properties
o Includes neighbor count and total flux out to three radii (currently set to 5”, 10” and 30”), closest neighbor distance, PA and nuv and fuv mag.
· Derived quantities and map levels at merged output position
o Includes extractions from pipeline-generated maps at the position of the detected source. Sky background [counts s-1 pixel-1], artifact [flag value], weight [exposure-relative response product], contrast [dimensionless] and masked pixel counts [number] values are given for each source.
· Sextractor output columns from FUV image extractions
· Sextractor output columns from NUV image extractions
o Please consult the sextractor manual and Sextractor for Dummies for definitions of these outputs
Catalog Fields
Table 3.2 Merged Object Catalog (-mcat.fits)
Name |
Format |
Unit |
Definition |
Object ID and orbpipe info |
|||
ggoid |
2J |
Number |
Galex Global Object ID |
vsn |
1J |
Number |
Version number |
tile |
1J |
Number |
Tile number |
type |
1J |
Number |
Obs.type (0=single,1=multi) |
ow |
1J |
Number |
Optics wheel (1=drct,2=grsm,3=opaq) |
prod |
1J |
Number |
Product number (_visits,_main,etc.) |
img |
1J |
Number |
image number (exposure# for _visits) |
try |
1J |
Number |
Try number (processing attempt number) |
band |
1J |
Number |
Band number (1=nuv,2=fuv,3=both) |
id |
1J |
Number |
Merged ID. |
Subvisit |
1I |
Number |
Sub-visit number for AIS |
leg |
1I |
Number |
Planned leg number for AIS |
Merged object quantities |
|||
alpha_j2000 |
1D |
Degrees |
Merged Right Ascension(degrees). |
delta_j2000 |
1D |
Degrees |
Merged Declination (degrees). |
prob |
1E |
Probability |
Chi-squared probability of match. |
sep |
1E |
Arcseconds |
Separation between band positions. |
Extinction |
1E |
Number |
E(B-V) Galactic Reddening. |
glon |
1E |
Degrees |
Galactic longitude in degrees. |
glat |
1E |
Degrees |
Galactic latitude in degrees. |
nuv_flux |
1E |
flux |
NUV calibrated flux |
nuv_fluxerr |
1E |
flux |
NUV calibrated flux error |
nuv_mag |
1E |
mag |
NUV calibrated magnitude |
nuv_magerr |
1E |
mag |
NUV calibrated magnitude error |
fuv_flux |
1E |
flux |
FUV calibrated flux |
fuv_fluxerr |
1E |
flux |
FUV calibrated flux error |
fuv_mag |
1E |
mag |
FUV calibrated magnitude |
fuv_magerr |
1E |
mag |
FUV calibrated magnitude error |
nuv_fcat_flux |
1E |
flux |
NUV calibrated flux using FUV catalog position |
nuv_fcat_fluxerr |
1E |
flux |
Error for nuv_fcat_flux |
fuv_ncat_flux |
1E |
flux |
FUV calibrated flux using NUV catalog position |
fuv_ncat_fluxerr |
1E |
flux |
Error for fuv_ncat_flux |
Nearest neighbor |
|||
nuv_nc_r1 |
1I |
number |
NUV neighbor count out to radius R1 |
nuv_nc_r2 |
1I |
number |
NUV neighbor count out to radius R2 |
nuv_nc_r3 |
1I |
number |
NUV neighbor count out to radius R3 |
fuv_nc_r1 |
1I |
number |
FUV neighbor count out to radius R1 |
fuv_nc_r2 |
1I |
number |
FUV neighbor count out to radius R2 |
fuv_nc_r3 |
1I |
number |
FUV neighbor count out to radius R3 |
nuv_nf_r1 |
1E |
flux |
NUV neighbor flux out to radius R1 |
nuv_nf_r2 |
1E |
flux |
NUV neighbor flux out to radius R2 |
nuv_nf_r3 |
1E |
flux |
NUV neighbor flux out to radius R3 |
fuv_nf_r1 |
1E |
flux |
FUV neighbor flux out to radius R1 |
fuv_nf_r2 |
1E |
flux |
FUV neighbor flux out to radius R2 |
fuv_nf_r3 |
1E |
flux |
FUV neighbor flux out to radius R3 |
cn_radius |
1E |
arcseconds |
Closest neighbor radius in arcseconds |
cn_pa |
1E |
degrees |
Closest neighbor position angle in degrees |
cn_mag_nuv |
1E |
mag |
Closest neighbor NUV magnitude |
cn_mag_fuv |
1E |
mag |
Closest neighbor FUV magnitude |
Image/detection map values |
|||
nuv_skybg |
1E |
flux |
NUV sky background flux (photons |
fuv_skybg |
1E |
flux |
FUV sky background flux (photons |
nuv_weight |
1E |
seconds |
NUV effective exposure (response) |
fuv_weight |
1E |
seconds |
FUV effective exposure (response) |
nuv_contrast |
1E |
ratio |
NUV ratio of min to max response near source |
fuv_contrast |
1E |
ratio |
FUV ratio of min to max response near source |
nuv_maskpix |
1J |
number |
NUV number of masked pixels near source |
fuv_maskpix |
1J |
number |
FUV number of masked pixels near source |
nuv_artifact |
1J |
number |
NUV artifact flag |
fuv_artifact |
1J |
number |
FUV artifact flag |
Band merger QA |
|||
nuv_ambg |
1J |
number |
NUV ambiguity flag. |
fuv_ambg |
1J |
number |
FUV ambiguity flag. |
nuv_nc |
1J |
number |
NUV number of candidates. |
fuv_nc |
1J |
number |
FUV number of candidates. |
nuv_cid1 |
1J |
number |
First candidate for NUV source(FUV IDs) |
fuv_cid1 |
1J |
number |
First candidate for FUV source(NUV IDs) |
nuv_cid2 |
1J |
number |
Second candidate for NUV source(FUV IDs) |
fuv_cid2 |
1J |
number |
Second candidate for FUV source(NUV IDs) |
nuv_cid3 |
1J |
number |
Third candidate for NUV source(FUV IDs) |
fuv_cid3 |
1J |
number |
Third candidate for FUV source(NUV IDs) |
Sourcepa |
1E |
degrees |
position angle betw. band sources. |
Objtype |
1J |
number |
0=galaxy,1=star,-1=unknown,etc. |
Quality |
1J |
number |
Quality flag (undefined) |
NUV source extraction catalog |
|||
NUV_NUMBER |
1J |
value |
Running object number |
NUV_FLUX_ISO |
1E |
flux |
Isophotal flux |
NUV_FLUXERR_ISO |
1E |
flux |
RMS error for isophotal flux |
NUV_MAG_ISO |
1E |
mag |
Isophotal magnitude |
NUV_MAGERR_ISO |
1E |
mag |
RMS error for isophotal magnitude |
NUV_FLUX_ISOCOR |
1E |
flux |
Corrected isophotal flux |
NUV_FLUXERR_ISOCOR |
1E |
flux |
RMS error for corrected isophotal flux |
NUV_MAG_ISOCOR |
1E |
mag |
Corrected isophotal magnitude |
NUV_MAGERR_ISOCOR |
1E |
mag |
RMS error for corrected isophotal magnitude |
NUV_FLUX_APER |
1E |
flux |
Flux vector within fixed circular aperture(s) |
NUV_FLUXERR_APER |
1E |
flux |
RMS error vector for aperture flux(es) |
NUV_MAG_APER |
1E |
mag |
Fixed aperture magnitude vector |
NUV_MAGERR_APER |
1E |
mag |
RMS error vector for fixed aperture mag. |
NUV_FLUX_AUTO |
1E |
flux |
Flux within a Kron-like elliptical aperture |
NUV_FLUXERR_AUTO |
1E |
flux |
RMS error for AUTO flux |
NUV_MAG_AUTO |
1E |
mag |
Kron-like elliptical aperture magnitude |
NUV_MAGERR_AUTO |
1E |
mag |
RMS error for AUTO magnitude |
NUV_FLUX_BEST |
1E |
flux |
Best of FLUX_AUTO and FLUX_ISOCOR |
NUV_FLUXERR_BEST |
1E |
flux |
RMS error for BEST flux |
NUV_MAG_BEST |
1E |
mag |
Best of MAG_AUTO and MAG_ISOCOR |
NUV_MAGERR_BEST |
1E |
mag |
RMS error for MAG_BEST |
NUV_ZPMAG |
1E |
mag |
NUV zero point magnitude correction. |
NUV_KRON_RADIUS |
1E |
pixel |
Kron apertures in units of A or B |
NUV_BACKGROUND |
1E |
count |
Background at centroid position |
NUV_THRESHOLD |
1E |
number |
Detection threshold above background |
NUV_MU_THRESHOLD |
1E |
number |
Detection threshold above background |
NUV_FLUX_MAX |
1E |
number |
Peak flux above background |
NUV_MU_MAX |
1E |
number |
Peak surface brightness above background |
NUV_ISOAREA_IMAGE |
1E |
number |
Isophotal area above Analysis threshold |
NUV_ISOAREA_WORLD |
1E |
number |
Isophotal area above Analysis threshold |
NUV_XMIN_IMAGE |
1J |
pixel |
Minimum x-coordinate among detected pixels |
NUV_YMIN_IMAGE |
1J |
pixel |
Minimum y-coordinate among detected pixels |
NUV_XMAX_IMAGE |
1J |
pixel |
Maximum x-coordinate among detected pixels |
NUV_YMAX_IMAGE |
1J |
pixel |
Maximum y-coordinate among detected pixels |
NUV_X_IMAGE |
1E |
pixel |
Object position along x |
NUV_Y_IMAGE |
1E |
pixel |
Object position along y |
NUV_XPEAK_IMAGE |
1J |
count |
x-coordinate of the brightest pixel |
NUV_YPEAK_IMAGE |
1J |
count |
y-coordinate of the brightest pixel |
NUV_ALPHA_J2000 |
1D |
degrees |
Right ascension of barycenter (J2000) |
NUV_DELTA_J2000 |
1D |
degrees |
Declination of barycenter (J2000) |
NUV_X2_IMAGE |
1E |
pixel |
Variance along x |
NUV_Y2_IMAGE |
1E |
pixel |
Variance along y |
NUV_XY_IMAGE |
1E |
pixel |
Covariance between x and y |
NUV_X2_WORLD |
1E |
number |
Variance along X-WORLD (alpha) |
NUV_Y2_WORLD |
1E |
number |
Variance along Y-WORLD (delta) |
NUV_XY_WORLD |
1E |
number |
Covariance between X-WORLD and Y-WORLD |
NUV_CXX_IMAGE |
1E |
number |
Cxx object ellipse parameter |
NUV_CYY_IMAGE |
1E |
number |
Cyy object ellipse parameter |
NUV_CXY_IMAGE |
1E |
number |
Cxy object ellipse parameter |
NUV_CXX_WORLD |
1E |
number |
Cxx object ellipse parameter (WORLD units) |
NUV_CYY_WORLD |
1E |
number |
Cyy object ellipse parameter (WORLD units) |
NUV_CXY_WORLD |
1E |
number |
Cxy object ellipse parameter (WORLD units) |
NUV_A_IMAGE |
1E |
number |
Profile RMS along major axis |
NUV_B_IMAGE |
1E |
number |
Profile RMS along minor axis |
NUV_A_WORLD |
1E |
number |
Profile RMS along major axis (world units) |
NUV_B_WORLD |
1E |
number |
Profile RMS along minor axis (world units) |
NUV_THETA_IMAGE |
1E |
degrees |
Position angle (CCW |
NUV_THETA_WORLD |
1E |
degrees |
Position angle (CCW |
NUV_THETA_J2000 |
1E |
degrees |
Position angle (east of north) (J2000) |
NUV_ELONGATION |
1E |
number |
A_IMAGE |
NUV_ELLIPTICITY |
1E |
number |
1 - B_IMAGE |
NUV_ERRX2_IMAGE |
1D |
number |
Variance of position along x |
NUV_ERRY2_IMAGE |
1D |
number |
Variance of position along y |
NUV_ERRXY_IMAGE |
1E |
number |
Covariance of position between x and y |
NUV_ERRX2_WORLD |
1D |
number |
Variance of position along X-WORLD (alpha) |
NUV_ERRY2_WORLD |
1D |
number |
Variance of position along Y-WORLD (delta) |
NUV_ERRXY_WORLD |
1E |
number |
Covariance of position X-WORLD |
NUV_ERRCXX_IMAGE |
1E |
number |
Cxx error ellipse parameter |
NUV_ERRCYY_IMAGE |
1E |
number |
Cyy error ellipse parameter |
NUV_ERRCXY_IMAGE |
1E |
number |
Cxy error ellipse parameter |
NUV_ERRCXX_WORLD |
1E |
number |
Cxx error ellipse parameter (WORLD units) |
NUV_ERRCYY_WORLD |
1E |
number |
Cyy error ellipse parameter (WORLD units) |
NUV_ERRCXY_WORLD |
1E |
number |
Cxy error ellipse parameter (WORLD units) |
NUV_ERRA_IMAGE |
1E |
number |
RMS position error along major axis |
NUV_ERRB_IMAGE |
1E |
number |
RMS position error along minor axis |
NUV_ERRA_WORLD |
1E |
number |
World RMS position error along major axis |
NUV_ERRB_WORLD |
1E |
number |
World RMS position error along minor axis |
NUV_ERRTHETA_IMAGE |
1E |
number |
Error ellipse position angle (CCW |
NUV_ERRTHETA_WORLD |
1E |
number |
Error ellipse pos. angle (CCW |
NUV_ERRTHETA_J2000 |
1E |
number |
J2000 error ellipse pos. angle (east of north) |
NUV_FWHM_IMAGE |
1E |
pixel |
FWHM assuming a gaussian core |
NUV_FWHM_WORLD |
1E |
deg |
FWHM assuming a gaussian core |
NUV_FLAGS |
1I |
value |
Extraction flags |
NUV_CLASS_STAR |
1E |
value |
S |
FUV source extraction catalog |
|||
FUV_NUMBER |
1J |
value |
Running object number |
FUV_FLUX_ISO |
1E |
flux |
Isophotal flux |
FUV_FLUXERR_ISO |
1E |
flux |
RMS error for isophotal flux |
FUV_MAG_ISO |
1E |
mag |
Isophotal magnitude |
FUV_MAGERR_ISO |
1E |
mag |
RMS error for isophotal magnitude |
FUV_FLUX_ISOCOR |
1E |
flux |
Corrected isophotal flux |
FUV_FLUXERR_ISOCOR |
1E |
flux |
RMS error for corrected isophotal flux |
FUV_MAG_ISOCOR |
1E |
mag |
Corrected isophotal magnitude |
FUV_MAGERR_ISOCOR |
1E |
mag |
RMS error for corrected isophotal magnitude |
FUV_FLUX_APER |
1E |
flux |
Flux vector within fixed circular aperture(s) |
FUV_FLUXERR_APER |
1E |
flux |
RMS error vector for aperture flux(es) |
FUV_MAG_APER |
1E |
mag |
Fixed aperture magnitude vector |
FUV_MAGERR_APER |
1E |
mag |
RMS error vector for fixed aperture mag. |
FUV_FLUX_AUTO |
1E |
flux |
Flux within a Kron-like elliptical aperture |
FUV_FLUXERR_AUTO |
1E |
flux |
RMS error for AUTO flux |
FUV_MAG_AUTO |
1E |
mag |
Kron-like elliptical aperture magnitude |
FUV_MAGERR_AUTO |
1E |
mag |
RMS error for AUTO magnitude |
FUV_FLUX_BEST |
1E |
flux |
Best of FLUX_AUTO and FLUX_ISOCOR |
FUV_FLUXERR_BEST |
1E |
flux |
RMS error for BEST flux |
FUV_MAG_BEST |
1E |
mag |
Best of MAG_AUTO and MAG_ISOCOR |
FUV_MAGERR_BEST |
1E |
mag |
RMS error for MAG_BEST |
FUV_ZPMAG |
1E |
mag |
FUV zero point magnitude correction. |
FUV_KRON_RADIUS |
1E |
pixel |
Kron apertures in units of A or B |
FUV_BACKGROUND |
1E |
count |
Background at centroid position |
FUV_THRESHOLD |
1E |
number |
Detection threshold above background |
FUV_MU_THRESHOLD |
1E |
number |
Detection threshold above background |
FUV_FLUX_MAX |
1E |
number |
Peak flux above background |
FUV_MU_MAX |
1E |
number |
Peak surface brightness above background |
FUV_ISOAREA_IMAGE |
1E |
number |
Isophotal area above Analysis threshold |
FUV_ISOAREA_WORLD |
1E |
number |
Isophotal area above Analysis threshold |
FUV_XMIN_IMAGE |
1J |
pixel |
Minimum x-coordinate among detected pixels |
FUV_YMIN_IMAGE |
1J |
pixel |
Minimum y-coordinate among detected pixels |
FUV_XMAX_IMAGE |
1J |
pixel |
Maximum x-coordinate among detected pixels |
FUV_YMAX_IMAGE |
1J |
pixel |
Maximum y-coordinate among detected pixels |
FUV_X_IMAGE |
1E |
pixel |
Object position along x |
FUV_Y_IMAGE |
1E |
pixel |
Object position along y |
FUV_XPEAK_IMAGE |
1J |
count |
x-coordinate of the brightest pixel |
FUV_YPEAK_IMAGE |
1J |
count |
y-coordinate of the brightest pixel |
FUV_ALPHA_J2000 |
1D |
degrees |
Right ascension of barycenter (J2000) |
FUV_DELTA_J2000 |
1D |
degrees |
Declination of barycenter (J2000) |
FUV_X2_IMAGE |
1E |
pixel |
Variance along x |
FUV_Y2_IMAGE |
1E |
pixel |
Variance along y |
FUV_XY_IMAGE |
1E |
pixel |
Covariance between x and y |
FUV_X2_WORLD |
1E |
number |
Variance along X-WORLD (alpha) |
FUV_Y2_WORLD |
1E |
number |
Variance along Y-WORLD (delta) |
FUV_XY_WORLD |
1E |
number |
Covariance between X-WORLD and Y-WORLD |
FUV_CXX_IMAGE |
1E |
number |
Cxx object ellipse parameter |
FUV_CYY_IMAGE |
1E |
number |
Cyy object ellipse parameter |
FUV_CXY_IMAGE |
1E |
number |
Cxy object ellipse parameter |
FUV_CXX_WORLD |
1E |
number |
Cxx object ellipse parameter (WORLD units) |
FUV_CYY_WORLD |
1E |
number |
Cyy object ellipse parameter (WORLD units) |
FUV_CXY_WORLD |
1E |
number |
Cxy object ellipse parameter (WORLD units) |
FUV_A_IMAGE |
1E |
number |
Profile RMS along major axis |
FUV_B_IMAGE |
1E |
number |
Profile RMS along minor axis |
FUV_A_WORLD |
1E |
number |
Profile RMS along major axis (world units) |
FUV_B_WORLD |
1E |
number |
Profile RMS along minor axis (world units) |
FUV_THETA_IMAGE |
1E |
degrees |
Position angle (CCW |
FUV_THETA_WORLD |
1E |
degrees |
Position angle (CCW |
FUV_THETA_J2000 |
1E |
degrees |
Position angle (east of north) (J2000) |
FUV_ELONGATION |
1E |
number |
A_IMAGE |
FUV_ELLIPTICITY |
1E |
number |
1 - B_IMAGE |
FUV_ERRX2_IMAGE |
1D |
number |
Variance of position along x |
FUV_ERRY2_IMAGE |
1D |
number |
Variance of position along y |
FUV_ERRXY_IMAGE |
1E |
number |
Covariance of position between x and y |
FUV_ERRX2_WORLD |
1D |
number |
Variance of position along X-WORLD (alpha) |
FUV_ERRY2_WORLD |
1D |
number |
Variance of position along Y-WORLD (delta) |
FUV_ERRXY_WORLD |
1E |
number |
Covariance of position X-WORLD |
FUV_ERRCXX_IMAGE |
1E |
number |
Cxx error ellipse parameter |
FUV_ERRCYY_IMAGE |
1E |
number |
Cyy error ellipse parameter |
FUV_ERRCXY_IMAGE |
1E |
number |
Cxy error ellipse parameter |
FUV_ERRCXX_WORLD |
1E |
number |
Cxx error ellipse parameter (WORLD units) |
FUV_ERRCYY_WORLD |
1E |
number |
Cyy error ellipse parameter (WORLD units) |
FUV_ERRCXY_WORLD |
1E |
number |
Cxy error ellipse parameter (WORLD units) |
FUV_ERRA_IMAGE |
1E |
number |
RMS position error along major axis |
FUV_ERRB_IMAGE |
1E |
number |
RMS position error along minor axis |
FUV_ERRA_WORLD |
1E |
number |
World RMS position error along major axis |
FUV_ERRB_WORLD |
1E |
number |
World RMS position error along minor axis |
FUV_ERRTHETA_IMAGE |
1E |
number |
Error ellipse position angle (CCW |
FUV_ERRTHETA_WORLD |
1E |
number |
Error ellipse pos. angle (CCW |
FUV_ERRTHETA_J2000 |
1E |
number |
J2000 error ellipse pos. angle (east of north) |
FUV_FWHM_IMAGE |
1E |
pixel |
FWHM assuming a gaussian core |
FUV_FWHM_WORLD |
1E |
deg |
FWHM assuming a gaussian core |
FUV_FLAGS |
1I |
Value |
Extraction flags |
FUV_CLASS_STAR |
1E |
Value |
S |
Primary Header Card for mcat.fits file
FITS Preamble
SIMPLE = T / file does conform to FITS standard
BITPIX = 16 / number of bits per data pixel
NAXIS = 0 / number of data axes
EXTEND = T / FITS dataset may contain extensions
COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H
ORIGIN = 'galexmerge.c'
Band Merger Input Files
NUVFILE = '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/AISCHV2_149_29047_0001_sv12-nd-cat.fits'
FUVFILE = '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/AISCHV2_149_29047_0001_sv12-fd-cat.fits'
NUVWTFIL= '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/AISCHV2_149_29047_0001_sv12-nd-rrhr.fits'
FUVWTFIL= '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/AISCHV2_149_29047_0001_sv12-fd-rrhr.fits'
NUVCNTFI= '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/AISCHV2_149_29047_0001_sv12-nd-cnt.fits'
FUVCNTFI= '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/AISCHV2_149_29047_0001_sv12-fd-cnt.fits'
NUVSKYFI= '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/AISCHV2_149_29047_0001_sv12-nd-skybg.fits'
FUVSKYFI= '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/AISCHV2_149_29047_0001_sv12-fd-skybg.fits'
NUVFLGFI= '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/AISCHV2_149_29047_0001_sv12-nd-flags.fits'
FUVFLGFI= '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/AISCHV2_149_29047_0001_sv12-fd-flags.fits'
Band Merger Parameters and Output Quantities
NUVS2N = 2. / Minimum S/N for NUV merges.
FUVS2N = 2. / Minimum S/N for FUV merges.
NUVS2NCU= 0. / S/N Cutoff for any NUV sources.
FUVS2NCU= 0. / S/N Cutoff for any FUV sources.
NUVNUM = 948 / Number of NUV sources.
FUVNUM = 207 / Number of FUV sources.
SEPLIM = 7. / Maximum separation in arcsec.
PROBLIM = 0. / Minimum probability for matches.
RPOSERR = 1.84049156740606 / Radial position error.
RA_CENT = 350.717645 / RA center for this field.
DEC_CENT= -0.389996 / DEC center for this field.
RAO = 350.717645 / RA center for this field.
DECO = -0.389996 / DEC center for this field.
TOTNUM = 1046 / Total number of sources.
TOTFILL = 109 / Number of filled sources.
TOTUFN = 839 / Number of unfilled NUV sources.
TOTUFF = 98 / Number of unfilled FUV sources.
LRGNUVID= 949 / Largest NUV ID number plus one.
N_ZPMAG = 20.0823753525469 / NUV Zero Point Magnitude
F_ZPMAG = 18.8170737879193 / FUV Zero Point Magnitude
N_ZPSCAL= 1. / NUV Zero Point Scale Factor
F_ZPSCAL= 1. / FUV Zero Point Scale Factor
CALMAG = 'AUTO ' / Calibration magnitude type
R1 = 5. / Neighbor radius limit 1 (arcsec)
R2 = 10. / Neighbor radius limit 2 (arcsec)
R3 = 30. / Neighbor radius limit 3 (arcsec)
N_AMBG0 = 839 / Number of NUV 0 ambig.
N_AMBG1 = 109 / Number of NUV 1 ambig.
N_AMBG2 = 0 / Number of NUV 2 ambig.
N_AMBG3 = 0 / Number of NUV 3 ambig.
N_AMBG4 = 0 / Number of NUV 4 ambig.
N_AMBG5 = 0 / Number of NUV 5 ambig.
N_AMBG6 = 0 / Number of NUV 6 ambig.
N_AMBGM6= 0 / Number of NUV -6 ambig.
N_AMBGM1= 0 / Number of NUV -1 ambig.
F_AMBG0 = 95 / Number of FUV 0 ambig.
F_AMBG1 = 109 / Number of FUV 1 ambig.
F_AMBG2 = 0 / Number of FUV 2 ambig.
F_AMBG3 = 3 / Number of FUV 3 ambig.
F_AMBG4 = 0 / Number of FUV 4 ambig.
F_AMBG5 = 0 / Number of FUV 5 ambig.
F_AMBG6 = 0 / Number of FUV 6 ambig.
F_AMBGM6= 0 / Number of FUV -6 ambig.
F_AMBGM1= 0 / Number of FUV -1 ambig.
COMMENT AMBG 0: unfilled, no candidates, no ambiguity.
COMMENT AMBG 1: filled, first choice candidates agree, no ambiguity.
COMMENT AMBG 2: filled, first choice matches second choice candidate.
COMMENT AMBG 3: unfilled, first choice taken, no second choice candidate.
COMMENT AMBG 4: filled, second choice matches a first choice candidate.
COMMENT AMBG 5: filled, second choice matches a second choice candidate.
COMMENT AMBG 6: unfilled, first and second taken, no third choice.
COMMENT AMBG -6: unfilled, first and second taken, third choice exists.
COMMENT AMBG -1: unfilled, cleared, unchecked.
COMMENT AMBG -2: not applicable, does not exist, blank.
FILENAME= '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/AISCHV2_149_29047_0001_sv12-xd-mcat.fits'
DIRECTRY= '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try/'
VSN = 1 / Reduction version (high level)
TILE = 10221 / Tile number (a.k.a. field or target)
TYPE = 1 / Observation type (0=single,1=multi)
OW = 1 / Optics wheel (1=drct,2=grsm,3=opaq)
PROD = 0 / Reduction product number (type)
IMG = 1537 / Image number (exposure or run)
TRY = 3 / Reduction try number (low level)
HISTORY NUV: HISTORY 03/11/03 00:22 Catalog created
Header card from NUV catalog file Sextractor Output
NEPOCH = 2000.
NOBJECT = 'AISCHV2_149_29047_0001_sv12'
NORIGIN = 'SExtractor'
NCRVAL1 = 350.717645
NCRVAL2 = -0.389996
NCRPIX1 = 1920.5
NCRPIX2 = 1920.5
NCDELT1 = -0.000416666666666667
NCDELT2 = 0.000416666666666667
NCROTA1 = 0.
NCROTA2 = 0.
Sextractor Parameters and Outputs (NUV)
NSXIMASX= 3840 / IMAGE WIDTH (PIXELS) originally SEXIMASX
NSXIMASY= 3840 / IMAGE HEIGHT (PIXELS)
NSXSTRSY= 1024 / STRIP HEIGHT (LINES)
NSXIMABP= -32 / FITS IMAGE BITPIX
NSXPIXS = 1.5 / PIXEL SCALE (ARCSEC)
NSXSFWHM= 4.5 / SEEING FWHM (ARCSEC)
NSXNNWF = 'default.nnw' / CLASSIFICATION NNW FILENAME
NSXGAIN = 71. / GAIN (IN E- PER ADU)
NSXBKGND= 0. / MEDIAN BACKGROUND (ADU)
NSXBKDEV= 0.006104021799 / MEDIAN RMS (ADU)
NSXBKTHD= 0.02816901356 / EXTRACTION THRESHOLD (ADU)
NSXCONFF= 'default.sex' / CONFIGURATION FILENAME
NSXDETT = 'CCD ' / DETECTION TYPE
NSXTHLDT= 'SIGMA ' / THRESHOLD TYPE
NSXTHLD = 1. / THRESHOLD
NSXMINAR= 10 / EXTRACTION MINIMUM AREA (PIXELS)
NSXCONV = T / CONVOLUTION FLAG
NSXCONVN= T / CONVOLUTION NORM. FLAG
NSXCONVF= 'gauss_3.0_7x7.conv' / CONVOLUTION FILENAME
NSXDBLDN= 32 / NUMBER OF SUB-THRESHOLDS
NSXDBLDC= 0.005 / CONTRAST PARAMETER
NSXCLN = T / CLEANING FLAG
NSXCLNPA= 1. / CLEANING PARAMETER
NSXCLNST= 32 / CLEANING OBJECT-STACK
NSXAPERD= 0 / APERTURE DIAMETER (PIXELS)
NSXAPEK1= 2.5 / KRON PARAMETER
NSXAPEK2= 2.5 / KRON ANALYSIS RADIUS
NSXAPEK3= 3.5 / KRON MINIMUM RADIUS
NSXSATLV= 999999999. / SATURATION LEVEL (ADU)
NSXMGZPT= 0. / MAGNITUDE ZERO-POINT
NSXMGGAM= 4. / MAGNITUDE GAMMA
NSXBKGSX= 128 / BACKGROUND MESH WIDTH (PIXELS)
NSXBKGSY= 128 / BACKGROUND MESH HEIGHT (PIXELS)
NSXBKGFX= 5 / BACKGROUND FILTER WIDTH
NSXBKGFY= 5 / BACKGROUND FILTER HEIGHT
NSXPBKGT= 'GLOBAL ' / PHOTOM BACKGROUND TYPE
NSXPBKGS= 24 / LOCAL AREA THICKNESS (PIXELS)
NSXPIXSK= 50000 / PIXEL STACKSIZE (PIXELS)
NSXFBUFS= 1024 / FRAME-BUFFER SIZE (LINES)
NSXISAPR= 0. / ISO-APER RATIO
NSXNDET = 1080 / NB OF DETECTIONS
NSXNFIN = 948 / NB OF FINAL EXTRACTED OBJECTS
NSXNPARA= 83 / NB OF PARAMETERS PER OBJECT
NUV Image and Exposure Data
NCTYPE1 = 'RA---TAN'
NCTYPE2 = 'DEC--TAN'
NEQUINOX= 2000.
NRA_CENT= 350.717645
NDEC_CEN= -0.389996 / originally DEC_CENT
NEXPTIME= 71.
NEXPSTAR= 1066079748.00512 / originally EXPSTART
NEXPEND = 1066079825.98502
NOBS-DAT= '2003-10-13' / originally OBS-DATE
NOBS-TIM= 'unknown ' / originally OBS-TIME
NOBSSECS= 1066079748.00512
NOBSDATI= '031013T211548Z' / originally OBSDATIM
NIMAGSZX= 3840
NIMAGSZY= 3840
NINTIMAG= '/home/ops1/tim/work/ir0.2/ais/AISCHV2_149_29047_0001/AISCHV2_149_29&'
CONTINUE '047_0001_sv12-nd-int.fits' / orginally INTIMAGE
HISTORY FUV: HISTORY 03/11/03 00:29 Catalog created
Header card from NUV catalog file Sextractor Output
FEPOCH = 2000.
FOBJECT = 'AISCHV2_149_29047_0001_sv12'
FORIGIN = 'SExtractor'
FCRVAL1 = 350.717645
FCRVAL2 = -0.389996
FCRPIX1 = 1920.5
FCRPIX2 = 1920.5
FCDELT1 = -0.000416666666666667
FCDELT2 = 0.000416666666666667
FCROTA1 = 0.
FCROTA2 = 0.
Sextractor Parameters and Outputs (FUV)
FSXIMASX= 3840 / IMAGE WIDTH (PIXELS) originally SEXIMASX
FSXIMASY= 3840 / IMAGE HEIGHT (PIXELS)
FSXSTRSY= 1024 / STRIP HEIGHT (LINES)
FSXIMABP= -32 / FITS IMAGE BITPIX
FSXPIXS = 1.5 / PIXEL SCALE (ARCSEC)
FSXSFWHM= 4.5 / SEEING FWHM (ARCSEC)
FSXNNWF = 'default.nnw' / CLASSIFICATION NNW FILENAME
FSXGAIN = 71. / GAIN (IN E- PER ADU)
FSXBKGND= 0. / MEDIAN BACKGROUND (ADU)
FSXBKDEV= 4.721388791E-08 / MEDIAN RMS (ADU)
FSXBKTHD= 0.02816901356 / EXTRACTION THRESHOLD (ADU)
FSXCONFF= 'default.sex' / CONFIGURATION FILENAME
FSXDETT = 'CCD ' / DETECTION TYPE
FSXTHLDT= 'SIGMA ' / THRESHOLD TYPE
FSXTHLD = 1. / THRESHOLD
FSXMINAR= 10 / EXTRACTION MINIMUM AREA (PIXELS)
FSXCONV = T / CONVOLUTION FLAG
FSXCONVN= T / CONVOLUTION NORM. FLAG
FSXCONVF= 'gauss_3.0_7x7.conv' / CONVOLUTION FILENAME
FSXDBLDN= 32 / NUMBER OF SUB-THRESHOLDS
FSXDBLDC= 0.005 / CONTRAST PARAMETER
FSXCLN = T / CLEANING FLAG
FSXCLNPA= 1. / CLEANING PARAMETER
FSXCLNST= 32 / CLEANING OBJECT-STACK
FSXAPERD= 0 / APERTURE DIAMETER (PIXELS)
FSXAPEK1= 2.5 / KRON PARAMETER
FSXAPEK2= 2.5 / KRON ANALYSIS RADIUS
FSXAPEK3= 3.5 / KRON MINIMUM RADIUS
FSXSATLV= 999999999. / SATURATION LEVEL (ADU)
FSXMGZPT= 0. / MAGNITUDE ZERO-POINT
FSXMGGAM= 4. / MAGNITUDE GAMMA
FSXBKGSX= 128 / BACKGROUND MESH WIDTH (PIXELS)
FSXBKGSY= 128 / BACKGROUND MESH HEIGHT (PIXELS)
FSXBKGFX= 5 / BACKGROUND FILTER WIDTH
FSXBKGFY= 5 / BACKGROUND FILTER HEIGHT
FSXPBKGT= 'GLOBAL ' / PHOTOM BACKGROUND TYPE
FSXPBKGS= 24 / LOCAL AREA THICKNESS (PIXELS)
FSXPIXSK= 50000 / PIXEL STACKSIZE (PIXELS)
FSXFBUFS= 1024 / FRAME-BUFFER SIZE (LINES)
FSXISAPR= 0. / ISO-APER RATIO
FSXNDET = 221 / NB OF DETECTIONS
FSXNFIN = 207 / NB OF FINAL EXTRACTED OBJECTS
FSXNPARA= 83 / NB OF PARAMETERS PER OBJECT
FUV Image and Exposure Data
FCTYPE1 = 'RA---TAN'
FCTYPE2 = 'DEC--TAN'
FEQUINOX= 2000.
FRA_CENT= 350.717645
FDEC_CEN= -0.389996 / originally DEC_CENT
FEXPTIME= 71.
FEXPSTAR= 1066079748.00532 / originally EXPSTART
FEXPEND = 1066079825.9851
FOBS-DAT= '2003-10-13' / originally OBS-DATE
FOBS-TIM= 'unknown ' / originally OBS-TIME
FOBSSECS= 1066079748.00532
FOBSDATI= '031013T211548Z' / originally OBSDATIM
FIMAGSZX= 3840
FIMAGSZY= 3840
FINTIMAG= '/home/ops1/tim/work/ir0.2/ais/AISCHV2_149_29047_0001/AISCHV2_149_29&'
CONTINUE '047_0001_sv12-fd-int.fits' / orginally INTIMAGE
DATE = '2003-11-06T21:15:56' / file creation date (YYYY-MM-DDThh:mm:ss UT)
GRELEASE= 'int-3.2-RC1'
ABSCAL = '/home/galex/cal/targ/cal01.00'
ABSPIPE = '/home/ops1/tim/work/ir0.2/ais/pipe/01-vsn/10221-AISCHV2_149_29047/d&'
CONTINUE '/00-visits/0001-img/03-try'
END
6. Pipeline Products Gallery
The images below show ds9 snapshots of some of the main pipeline image products. FUV images are on the left, NUV on the right. Specific details can be seen in the magnifier image (upper right), which is providing a zoom around the cursor position (indicated by the white arrow in the image).
These images have been obtained from the pipeline a single visit to the target M51 (NGA_M51_0001)
Dose Map
The dose map contains photon positions in the instrument frame. The full field of view is 65 mm diameter, or 1.24 degrees in the telescope focal plane. Note that the NUV image frame is rotated 180 degrees from the FUV frame.
Because of the dither motion by the satellite, stars and galaxies move in this frame during an observation (appearing in this image as donuts or smeared objects). Point sources in these images are “detector hot spots” which are masked in further processing.
The four points at the corners are the images are generated by electronic stimulus pulses in the detector system. These are used for calibration of electronic drift and dead time corrections only and do not show up in the final images.
Count Map
The combination of time-tagged photon positions and satellite aspect satellite are used to generate a count map in sky coordinates. This observation was acquired at a roll angle of 90 degrees (measured with respect to the Y axis of the detector/instrument frame), which explains why the image is rotated with respect to the dose maps above.
The image quantities are in units of counts per pixel. Each pixel is 1.5”x1.5”. Note that at the position of the arrow, 50 counts were detected in this exposure.
Relative Response Map
The high resolution relative response map shows the effective normalized instrument response (based on flat field) * exposure (seconds) projected onto the sky. The small donuts result from regions of the detector active area (hot spots) which have been masked in pipeline processing.
Over most of the active area, the response varies by less than +/- 20%. The FUV detector shows much larger response variation across the field, particularly on one side where the response drops off significantly.
Intensity map
The intensity map is generated by dividing the count map by the relative response map. The units are in counts / pixel s (normalized effective area*bandwidth), which means that while the image is ‘flattened’ to reflect the true instrument response, the units correspond roughly to counts per second per pixel. At the position of the arrow (highlighted in the magnifier), we detected ~ 0.082 counts/(s normalized EA pixel) in the NUV image. This can easily be converted to a surface brightness using the conversion factors provided in the table above.
Note that in the low response region of the FUV detector, the average level is relatively flat, but the image becomes noisy as expected due to the low throughput in this region.
Sky Background Map
The GALEX pipeline generates a smoothed sky background map which is subtracted from the intensity image prior to the final source extraction processing step.
Grism Intensity Maps
Intensity maps are also built up in grism mode. The quad image below shows imaging and grism intensity maps of the ELAISS1_00 field. The grism data are from a single visit (and grism rotation).
7. GALEX Image Artifacts
The GALEX optics and detector produce several image artifacts which the pipeline flags to indicate regions where analysis problems may arise. Most image artifacts are observed in the NUV channel due to a bevel on the edge of the NUV window and the abundance of bright stars detected vs. the FUV. The principal artifacts are:
- Bright star halos (both)
- Bright star NUV beveled edge reflections (NUV only)
- Dichroic ghosts (NUV only)
- Detector window ghosts (both)
- Near-field stray light from bright stars
Other artifacts are produced by transient effects. These include
- Unmasked detector hot spots
- Satellite transits
- Asteroid motion
- Local flaring of detector count rate caused by South Atlantic Anomaly, solar activity
The pipeline flags possible artifacts for the NUV detector and masks known detector hot spots.
Table 3.3 -- Artifact Gallery
Artifact |
Pipeline Flag |
Picture [NUV=red/yellow, FUV=blue] |
Bright star halo [NUV] Due to diffraction, and electron halo due to proximity focused photocathode. |
NONE |
|
Bright star halo [FUV] |
NONE |
|
Ghosts—Window & Dichroic The largest (red, lower) ghost is due to the 10 mm thick NUV detector window. Detector window ghosts are radially offset due to curvature on the window. The small ghost to the upper right is due to the dichroic beam splitter. It is offset along the detector Y-axis (instrument X-axis) and oblique due to the oblique angle of the beam splitter. |
|
|
FUV hot spot Normally masked out in pipeline, new hotspots not in database will appear as spiral echoing dither pattern (since hot spots are fixed in detector coordinates). |
|
|
NUV Window Bevel Reflection Edge Ghost The NUV window has a beveled exterior surface required to mate to the microchannel plate surface. Total internal reflection causes light from stars within 5 arcminutes of the edge to reflect into the field of view. Depending on the exact location of the star, a ghost image can be produced far inside the field of view, as shown in the next image |
|
|
NUV Window Bevel Reflection Interior Ghost |
|
Responsible NASA Official: Susan G. Neff
Curators: Joan E. Hollis and Joel D. Offenberg