GALEX Grism Calibration

Four stars around 4 hours RA (November 2008):
HZ 2    0412+11  14.02   (lots of grism data, but few field stars)
GD 50   0348-00  14.05   (good field, 2.1 times brighter than HZ 2)
HZ 4    0355+09  14.45   (good field, 2.9 times fainter than HZ 2)
LB 227  0409+17  15.24   (7.7 times fainter than HZ 2)

Comparison between 2004 and 2007 calibrations: NUV 1st order ... FUV 2nd order ...

Comparison between Old ETC(<=2007) and New 2007 calibrations: NUV 1st order ... FUV 2nd order

Ground Calibration
ASCII tables of effective area:
EA_ground-nuv_1.tbl ... EA_ground-nuv_2.tbl ... EA_ground-fuv_2.tbl ... EA_ground-fuv_3.tbl
Space Calibration (as of 02 April 2004) (based on BD+33)
ASCII tables of effective area:
EA_02apr04-nuv_1.tbl ... EA_02apr04-nuv_2.tbl ... EA_02apr04-fuv_2.tbl ... EA_02apr04-fuv_3.tbl

Plots of ground vs. space calibration: ... ... ...

Here are the current (June 2004) wavelength cutoffs used for the final reduced spectra: extraction_ranges_jun04.txt .

Plots of relative variations of response among 42 spectra of BD+33 taken at different grism angles and different detector positions:
NUV 1st order (PS) ... NUV 2nd order (PS) ... FUV 2nd order (PS) ... FUV 3rd order (PS)

Tar file of ASCII tables of flux calibration (based on BD+33). Files contain four columns of wavelength, extracted flux (pho/sec/cm^2/sec), HST calibration spectrum, and smoothed HST calibration standard. Files with the same first 5 letters were taken during the same visit with the star at different positions on the detector.

GALEX Standard Stars for Grism Calibration

GIF image (10 x 10 arcmin): BD+33d2642 HZ 44 ... ...
GRSPA table (5=best,1=worst): BD+33d2642 HZ 44 ... ...
Plot of GRSPA angles: BD+33d2642 HZ 44 ... ...
Spectral data (Flam v. Ang): BD+33d2642 HZ 44 LDS 749B G 93-48
Simulated GALEX Spectra Plots: BD+33d2642 HZ 44 ... ...
List of observations: BD+33d2642 HZ 44 LDS 749B G 93-48
Coordinate Name (2000): 1551+3256 1323+3608 2132+0015 2152+0223
RA,Dec (2000): 237.99942, +32.94856 200.897375, +36.133333 323.06563, +00.25378 328.10554, +02.39008

Simulated LDS 749b plots (with 0.65 pessimism factor):
NUV pho/sec ... FUV pho/sec ... Flux Calibrated ... S/N per second per 5 Angstrom bin .
Simulated GALEX Spectral Plots with noise (red line is calibration spectrum):
BD+33: (100 seconds) (500 seconds) (1500 seconds)
HZ 44: (100 seconds) (500 seconds) (1500 seconds)

Simulated GALEX Spectral ASCII Tables:
BD+33: (FUV) (NUV) (Flux 1500s)
HZ 44: (FUV) (NUV) (Flux 1500s)

CALSPEC (link to
CALSPEC (copy of web page with table of stars)
HST Standards (list of stars)
Spectral Plots of HST Standards (PS)
Standard Star List (
GRSPA Diagram (GIF)
Grism Offset vs. Wavelength (PS)
Grism Dispersion (Angstroms per Arcsecond) (PS)
Grism Resolution in Angstroms (5" PSF) (PS)
Grism Resolution in km/s (5" PSF) (PS)

First grism spectra.
Compare BD+33 Estimate with actual spectrum from Eclipse 455 on (pho/sec/arcsec vs. offset arcsecond)
Division of Actual by Estimate on arcsecond scale
Real vs. Actual on (Flux vs. Angstrom)