Candidates for XRF030824
by A. Klotz, F. Malacrino, J.L. Atteia, M. Boer (CESR-LAT/OMP
Toulouse), D. Fox, M.P. Hunt (Caltech), C. Veillet (CFHT)
1. The images
This analysis is a comparision between an early (1day after GRB) and a
late image (28 days after GRB).
Early image : Palomar 5 meters started at 2003-08-25T05:41:30 -
exptime1200s (= 4x300s) - Filter R_Steidel (close to Sloan r') - composite
of 4 images taken between 05:41:30 and 06:04:56 UT.
Late image : CFHTLS started at 2003-09-21T07:56:32.60 - exptime
300.057s - filter I (i.MP9701)
The covered field for comparison is limited by the palomar image :
Sampling 0.35 arcsec for Palomar and 0.19 arcsec for CFHTLS.
Astrometric calibration was not accurate due partly by non linear deformations.
Empirical corrections were added for this processing.
Image PSF is not round on the external parts of the field of Palomar.
The limiting magnitude is about 1 mag deeper for Palomar. As a consequence,
it is not easy to identify a candidate amongst faint stars.
2. The method of inspection
A. Klotz method :
1. Images were windowed to small 500x500 images.
2. Images were blinked each other.
3. A visual examination.
F. Malacrino method :
1. List of objects are extracted with Sextractor.
2. Comparision of lists.
Below, field images of candidates (1x1 arcmin, north up, east left)
=========================
Image : 718657p13
Position xy : 1842.491641 1259.4974
Comment : Alain candidate 1 (best Alain candidate for a SN/GRB)
Position radec : 00h05m12s30 +20d06m29s4 (accuracy +/- 0.2 arcsec)
Magnitude : I=22.7 +/- 0.2
No host galaxy detected
Palomar
|
CFHTLS
|
=========================
Image : 718657p13
Position xy : 1434.3940 1738.1860
Comment : Fred candidate 1 (best Fred candidate for a SN/GRB)
Position radec : 00h05m06s82 +20d05m00s4 (accuracy +/- 0.4 arcsec)
Magnitude : I=22.6 +/- 0.4
Offsets from host galaxy : 0.56 arcsec W and 0.55 arcsec N
Magnitude of the host anonymous galaxy : I=21.5 +/- 0.2
Palomar
|
CFHTLS
|
=========================
Image : 718657p13
Position xy : 1688.0410 1287.5000
Comment : Fred candidate 2 (star mag varied)
Position radec : 00h05m10s35 +20d06m22s97
Position radec : 1.293126 20.1063815
Palomar
|
CFHTLS
|
=========================
Image : 718657p22
Position xy : 1154.3190 3453.7010
Comment : Fred candidate 3 (star mag varied)
Position radec : 00h05m00s92 +19d52m16s66
Position radec : 1.253866 19.8712945
Palomar
|
CFHTLS
|
=========================
Image : 718657p21
Position xy : 1206.9100 3903.7830
Comment : Fred candidate 4 (false candidate, it is a cosmic on CFHT image)
Position radec : 00h05m28s25 +19d53m42s27
Position radec : 1.36771 19.8950755
Palomar
|
CFHTLS
|
=========================
Image : 718657p23
Position xy : 173.90200 799.10900
Comment : Fred candidate 5 (star mag varied)
Position radec : 00h04m45s83 +19d43m59s50
Position radec : 1.190996 19.7331955
Palomar
|
CFHTLS
|
