GRB 071025
GCN Circular 6986
Subject
GRB 071025: Swift detection of a burst
Date
2007-10-25T04:30:05Z (18 years ago)
From
Claudio Pagani at PSU/Swift-XRT <pagani@astro.psu.edu>
C. Pagani (PSU), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC),
C. Gronwall (PSU), C. B. Markwardt (CRESST/GSFC/UMD),
F. E. Marshall (NASA/GSFC), J. L. Racusin (PSU),
T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the
Swift Team:
At 04:08:54 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 071025 (trigger=295301). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 355.084, +31.757 which is
RA(J2000) = 23h 40m 20s
Dec(J2000) = +31d 45' 24"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). Although this is a 64 sec image trigger,
the light curve appears to have a single broad peak with duration
about 120 sec near time T+100, with peak count rate 2000 ct/s.
The XRT began observing the field at 04:11:19 UT, 146 seconds after the
BAT trigger. XRT found a bright, fading, uncatalogued X-ray source
located at RA, Dec 355.0765, +31.7776 which is
RA(J2000) = 23h 40m 18.3s
Dec(J2000) = 31d 46' 39.3"
with an uncertainty of 6.8 arcseconds (radius, 90% containment).
This location is 78 arcseconds from the BAT on-board position,
within the BAT error circle. The initial flux in the 0.1s image
was 9.1e-09 erg/cm2/s (0.2-10 keV).
UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 155 seconds after the BAT trigger. No afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 18.5 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.08.
Burst Advocate for this burst is C. Pagani (pagani AT astro.psu.edu).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN Circular 6987
Subject
GRB 071025: ROTSE-III Detection of Optical Counterpart
Date
2007-10-25T04:37:51Z (18 years ago)
From
Eli Rykoff at U of Michigan/ROTSE <erykoff@umich.edu>
E.S. Rykoff (UCSB), F. Yuan (U Mich), B. E. Schaefer (Louisiana State),
H. Swan (U Mich), R. Quimby (Caltech), report on behalf of the ROTSE
collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB
071025 (Swift trigger 295301, GCN 6986). The first image was at
04:10:14.0 UT, 80.3 s after the burst (6.0 s after the GCN notice time).
The unfiltered images are calibrated relative to USNO A2.0. We detect a
19.2 magnitude, fading source with coordinates:
23:40:17.19 +31:46:42.64 (J2000), with positional
uncertainty of 1" or better
start UT mag mlim(of image)
----------------------------------
04:16:27.1 19.2 18.6
This source is not visible in DSS (second epoch), 2MASS or the MPChecker
database.
A jpeg image is available at
http://www.rotse.net/images/gsb295301_3b021-030_key.jpg
Continuing observations are in progress.
GCN Circular 6988
Subject
GRB071025: REM NIR afterglow
Date
2007-10-25T04:48:54Z (18 years ago)
From
Stefano Covino at Brera Astronomical Observatory <stefano.covino@gmail.com>
S. Covino, S. Piranomonte, D. Fugazza, L.A. Antonelli, L. Calzoletti,
S. Campana, G. Chincarini, M.L. Conciatore, S. Cutini, P. D'Avanzo,
V. D'Elia, F. Dalessio, F. Fiore, P. Goldoni, D. Guetta, C.
Guidorzi, G.L. Israel, N. Masetti, A. Melandri, E. Meurs, L.
Nicastro, E. Palazzi, E. Pian, S. Piranomonte, L. Stella, G.
Stratta, G. Tagliaferri, G. Tosti, V.
Testa, S.D. Vergani, F. Vitali report on behalf of the REM team:
The NIR afterglow is detected by the REM telescope at coordinates:
RA = 23:40:17.1
DEC = 31:46:43.6
with H~13.8 at 4:18:12 UT.
The source is NOT in the XRT error circle, although rather close to
it. The source is bright, and not present in the 2MASS or USNO
catalogues. The source is compatible with that reported by Rykoff et
al. (GCN 6987).
Further observations are in progress.
GCN Circular 6990
Subject
GRB 071025: Swift XRT refined position
Date
2007-10-25T05:19:35Z (18 years ago)
From
Claudio Pagani at PSU/Swift-XRT <pagani@astro.psu.edu>
C. Pagani (PSU) reports on behalf of the Swift-XRT Team:
The XRT on-board centroid position of the afterglow of GRB 071025 reported in
GCN 6986 was strongly affected by a hot column.
A refined position from the first 0.1 second image is RA, Dec=355.0737, 31.7782
which is
RA(J2000) =23h 40m 17.7s
Dec(J2000) =+31d 46' 41.4"
with an uncertainty of 8 arcseconds (radius, 90% containment).
This is 9 arcseconds from the initial XRT position, and 6.5 arcseconds from the
optical position reported in GCN 6897.
This circular is an official product of the Swift-XRT team.
GCN Circular 6991
Subject
GRB 071025: I-detection, R-dropout?
Date
2007-10-25T05:43:23Z (18 years ago)
From
Myungshin Im at Seoul Nat U <mim@astro.snu.ac.kr>
M. Im, I. Lee (Seoul National University), and Y. Urata
(Saitama University) on behalf of the EAFON team:
Using the Mt. Lemmon (Arizona, US) 1.0m telescope
operated by the Korea Astronomy Space Science Institute,
we observed GRB071025, beginning at 04:35 UT on Oct 25.
We have a clear detection of the afterglow in 300 secs frame
taken in I-band (GCN6987, Rykoff et al.),
but no detection at all in B, V, R-band with the same exposure
time. The non-detection R-band suggests that the GRB is
likely a R-band dropout at z ~ 6.
This message may be cited.
We acknowldege the help of the LOAO operators, J.H. Yoon,
for this observation.
GCN Circular 6992
Subject
GRB 071025: ROTSE-III Refined Analysis
Date
2007-10-25T06:54:28Z (18 years ago)
From
Eli Rykoff at U of Michigan/ROTSE <erykoff@umich.edu>
E.S. Rykoff (UCSB), F. Yuan (U Mich), B. E. Schaefer (Louisiana
State), H. Swan (U Mich), R. Quimby (Caltech), report on behalf of the
ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB
071025 (Swift trigger 295301, GCN 6986, Pagani, et al.) and detected
an optical counterpart as reported in GCN 6987 (Rykoff, et al.). We
have improved the photometry and recalibrated the images relative to
USNO-B1.0 R-band, which is significantly offset from the magnitudes in
USNO-A2.0 R-band.
From our initial observations at T+80.3s we see the counterpart rise
to a peak of 17.3+/-0.2 at T+332s (midtime for a 40s coadd), and then
fade slowly over the next 1500 s. At T+595s (midtime for a 280s
coadd) the magnitude is 17.6+/-0.1. This integration is nearly
simultaneous with the NIR detections of H~13.8 (Covino, et al., GCN
6988) and J=14.95 (Bloom, et al., GCN 6989).
Although the ROTSE-III images are calibrated relative to R-band, the
unfiltered CCD has significant sensitivity redward of R. Our
observations are thus consistent with a possible R-band dropout (Im,
et al., GCN 6991) and UVOT non-detection (Pangani, et al., GCN 6986).
We can assume that the intrinsic GRB spectrum as an R-J color of ~1,
and the reddening is entirely caused by the intergalactic medium
(IGM). We then use the ROTSE-III magnitude and the integrated
ROTSE-III response curve convolved with the IGM absorption model of
Meiksin (2005) to estimate an upper limit on the burst redshift of
z~5.3 (for more details see Ruiz-Velasco, et al, 2007). We note that
at this redshift the R-band offset would be ~1.2 mag, which may be
consistent with the limits of Im, et al. However, if the reddening is
not caused by absorption in the IGM then the burst redshift may be
lower.
GCN Circular 6994
Subject
GRB 071025: R/I-band update
Date
2007-10-25T07:56:36Z (18 years ago)
From
Myungshin Im at Seoul Nat U <mim@astro.snu.ac.kr>
M. Im, I. Lee (Seoul National University), and Y. Urata
(Saitama University) on behalf of the EAFON team:
We coninue examination of the data obtained with
the Mt. Lemmon (Arizona, US) 1.0m telescope. The afterglow appears
to be decaying rapidly after ~2400 secs of the burst.
Re-examination of R-band images show a faint smudge which could
be due to the afterglow. The detection is consistent with GCN
report 071025 (Rykoff et al.), and we set the limit of R -I > ~1.7 mag
from our R-band observation. Note that our R-band filter has a
long tail toward red wavelenth.
Below are rough estimates of I-band magnitudes based on USNO-B stars
(error ~ 0.15mag).
Star time (UT) Exp Time I mag
--------------------------------------
04:38:08 300s 16.8
05:08:42 300s 17.2
05:30:48 300s 18.1
Further examination of the BVRI data is ongoing to check
whether this is a red GRB or high-z GRB.
This message may be cited.
We acknowldege the help of the LOAO operators, J.H. Yoon,
for this observation.
GCN Circular 6995
Subject
GRB 071025: Early Super-LOTIS Observations
Date
2007-10-25T09:54:28Z (18 years ago)
From
Grant Williams at Steward Observatory <ggwilli@gmail.com>
G. G. Williams (MMTO) and P. A. Milne (Steward Observatory), on behalf of the
Super-LOTIS Collaboration, report:
The robotic 0.6-m Super-LOTIS telescope began observing the error box
of GRB 071025 (Swift Trigger 295301, Pagani et al. GCN 6986) at
04:10:29.3 UT, 95 seconds after the trigger. Our initial observations
include 5 x 10s exposures, 5 x 20s exposures, and 30 x 60s exposures,
all in the R-band.
We detect the afterglow reported by Rykoff et al. (GCN 6987,
confirmed by Covino et al. GCN 6988) in the sum of our first ten 60s
exposures centered on 04:19:39 UT. We do not detect the afterglow in
our single 10s or 20s exposures. Using USNO-B1.0 stars we estimate the
following R-band magnitude and upper limits for the OT:
t_start (UT) t_mid (UT) exp t (s) t_start-t_0 (s) R Mag
-----------------------------------------------------------------------------------------------------
04:10:29.3 04:10:34.3 10 95.3 R > 17.3
04:13:42.1 04:13:52.1 20 288.1 R > 17.8
04:14:08.8 04:19:39.0 600 314.8 R =
17.97 +/- 0.17
Our upper limit of R > 17.8 was measured near the time of the
unfiltered m=17.3 peak reported by Rykoff et al. (GCN 6992).
Additional observations and analysis are ongoing.
GCN Circular 6996
Subject
GRB 071025, Swift-BAT refined analysis
Date
2007-10-25T11:29:48Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL),
N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
C. Pagani (PSU), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+422 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 071025 (trigger #295301)
(Pagani, et al., GCN Circ. 6986). The BAT ground-calculated position is
RA, Dec = 355.065, 31.784 deg, which is
RA(J2000) = 23h 40m 15.6s
Dec(J2000) = 31d 47' 3"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 48%.
The mask-weighted light curve shows a broad peak composed of several overlapping
subpeaks. It starts at ~T+0 sec, peaks around T+90 sec, and slowly decays
out to at least T+422 sec. Because of an observing constraint, the s/c had to slew
off the burst location, and so we do not have any information on the continuation
of the emission beyond the T+422 sec limit. T90 (15-350 keV) is at least 109 +- 2 sec
(estimated error including systematics).
The time-averaged spectrum from T+38.5 to T+193.8 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.79 +- 0.05. The fluence in the 15-150 keV band is 6.5 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+80.17 sec in the 15-150 keV band
is 1.6 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
GCN Circular 6998
Subject
GRB 071025: Swift-XRT Team refined analysis
Date
2007-10-25T14:14:05Z (18 years ago)
From
Claudio Pagani at PSU/Swift-XRT <pagani@astro.psu.edu>
C. Pagani, D. N. Burrows, J. Racusin (PSU), P. Evans (U Leicester) report on
behalf of the Swift-XRT Team:
We have analysed the first three orbits of Swift-XRT data obtained for GRB
071025 (Pagani et al. GCN Circ. 6986), totalling 250 s of Windowed Timing (WT)
data and 2.7 ks of Photon Counting (PC) data.
Using 1189 seconds of overlapping XRT Photon Counting mode and UVOT V-band data,
we find an astrometrically corrected X-ray position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
355.07142, 31.77857 which is equivalent to:
RA (J2000): 23 40 17.14
Dec (J2000): +31 46 42.9
with an uncertainty of 1.7 arcsec (radius, 90% confidence). This is 7.1 arcsec
from the refined XRT position (GCN Circ. 6990) and 0.7 arcsec from the optical
afterglow found by ROTSE-III at McDonald Observatory (Rykoff et al., GCN Circ.
6987).
The bright X-ray light-curve can be fitted by a broken power-law, with an
initial steep decay index of 2.8 +/- 0.3 followed by a flatter decay index of
1.5 +/- 0.1 after a break at 260 +/- 20 seconds.
The WT data (150-400 seconds) can be modelled as an absorbed power-law, with
Gamma = 1.40 +/- 0.05 and a total absorbing column of NH = (0.9 +/- 0.1)e21
cm^-2, in excess of the Galactic value of 5.1e20 cm^-2. The 0.3-10 keV observed
(unabsorbed) flux during this time is 2.0e-09(2.2e-09) erg cm^-2 s^-1.
Assuming the source continues to decay with the same decay index of 1.5, we
predict an XRT count rate of 7E-3 counts/s at T+24 hours, which corresponds to
an observed flux of 4E-13 ergs cm^-2 s^-1.
This circular is an official product of the Swift-XRT team.
GCN Circular 6999
Subject
GRB071025: Xinglong TNT I-band upper limit
Date
2007-10-25T17:51:37Z (18 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
L.P. Xin, M. Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng,
J. Wang , Y. Urata and W.K. Zheng on behalf of EAFON report:
We have observed the field of GRB071025(C. Pagani , GCN 6986)
with TNT 0.8m telescope at Xinglong observatory, started from
10:27:28.296 UT, about 6.3 hours after the burst. The wheter was
not good. A series of I-band images were obtained, and no new
source was found in our 18*240s combined image within the
error region of the XRT(C. Pagani, GCN6986 GCN6990) and the
locations reported by E.S. Rykoff(GCN 6987); S. Covino (GCN 6988);
J. S. Bloom (GCN 6989;).
the 3 sigma limit of our combined image derived from USNO-B1.0
Imag was I =18.2 mag at the mean time of 7.1 hours after the burst.
This message may be cited.
GCN Circular 7001
Subject
GRB071025: Optical Pre-imaging from Palomar
Date
2007-10-25T19:00:59Z (18 years ago)
From
Nat Butler at MIT/CSR <nrbutler@space.mit.edu>
P. Nugent (LBL), N. Butler, J.S. Bloom, and D. Perley (UC Berkley) report:
We have created a stacked image through the co-addition of 12 unfiltered
images taken by the NEAT collaboration and 45 images in the RG610 filter
taken by the Palomar-Quest Consortium at the Palomar Oschin Schmidt
telescope (obtained from 2001-2007), of 071025 (Pagani et al.; GCN #6986).
The stacked image is significantly deeper than the DSS (3 sigma limit of
R~22.8 mag).
There is no source at the position of the counterpart (Rykoff et al. GCN #6987,
Covino et al. GCN #6988, Bloom et al. GCN #6989). The image is available at
http://www.lbl.gov/~nugent/deepsky.html
This message may be cited.
GCN Circular 7003
Subject
GRB 071025: SQIID JHK photometry
Date
2007-10-25T22:43:19Z (18 years ago)
From
Xiaohui Fan at U of Arizona <fan@as.arizona.edu>
L. Jiang, F. Bian, X. Fan (Steward Observatory, University of Arizona)
reports:
Using the Simultaneous Quad Infrared Imaging Device (SQIID) on the Kitt
Peak Mayall 4-meter Telescope, we observed GRB 071025 in J, H, K bands
simultaneously, beginnig at UT 2007-10-25-05:56:59. With total exposure
time of 240 sec in all three bands, we clearly detected the afterglow.
Calibrated using local 2MASS sources, the object is at
J=17.34 +/- 0.05
H=16.37 +/- 0.05
K=15.45 +/- 0.05
The photometric errors are dominated by the zeropoint uncertainties from our
calibration procedure. The photon noise on the measuremens is <0.01.
The message may be cited.
--
Xiaohui Fan
Steward Observatory
The University of Arizona
933 N. Cherry Ave.
Tucson, AZ 85721-0065
Email: fan@as.arizona.edu
Tel: (520) 626-7558
Fax: (520) 621-1532
URL: http://sancerre.as.arizona.edu/~fan
GCN Circular 7004
Subject
GRB 071025 Milagro GeV/TeV Observations
Date
2007-10-25T23:08:35Z (18 years ago)
From
Pablo Saz Parkinson at UCSC/Milagro <pablo@scipp.ucsc.edu>
Pablo Saz Parkinson (UC Santa Cruz) on behalf of the Milagro
collaboration reports:
We have searched Milagro data for emission at GeV/TeV energies from
GRB 071025 detected by Swift (GCN Circ 6986, C. Pagani et al.),
during the main period of emission lasting 422s (GCN Circ 6996, S. D.
Barthelmy et al.). No evidence for prompt GeV/TeV emission was found.
TeV photons are attenuated by pair production with infrared photons in
intergalactic space. We calculate uppers limits using the extragalactic
infrared background light (EBL) absorption model of
Primack et al. 2005 (AIP Conf. Proc. 745, p. 23).
A preliminary analysis, assuming a differential photon spectral
index of -2.4, gives upper limits on E^2dN/dE at 99% confidence of:
E^2 dN/dE at 200 GeV < 1.4 * 10^(-6) erg cm^(-2) (Assuming z=0)
and
E^2 dN/dE at 200 GeV < 2.3 * 10^(-5) erg cm^(-2) (Assuming z=0.5)
E^2 dN/dE at 200 GeV < 2.0 * 10^(-3) erg cm^(-2) (Assuming z=2.0)
These upper limits are preliminary and will be refined with further
analysis.
GCN Circular 7005
Subject
GRB 071025: SARA VRI upper limits
Date
2007-10-26T02:59:27Z (18 years ago)
From
Adria C. Updike at Clemson U <aupdike@clemson.edu>
Adria C. Updike, Dieter H. Hartmann (Clemson University), Evan Bryson,
Matt Cefalu, and Todd Hillwig (Valparaiso University) report on behalf
of the Clemson GRB Follow-Up Team:
We observed the field of GRB 071025 (GCN 6986, Pagani et al.) with the
0.9m SARA telescope on Kitt Peak beginning 49 minutes after the
trigger. Our observations consisted of R, V, and I band exposures under
good weather conditions. We do not detect the afterglow (GCN 6987,
Rykoff et al.) in any of our stacked images.
Times are given in days after the trigger. R and I magnitudes were
determined based on calibration to 10 USNO B1.0 field stars. V
magnitudes were found relative to 5 NOMAD field stars.
Start time End time Exp Mag
----------------------------------------------------------
0.03394 0.04328 4x180s R > 18.6
0.04405 0.05559 2x180s + 2x240s V > 19.1
0.05586 0.10521 10x240s I > 19.3
The SARA website may be found at http://astro.fit.edu/sara/sara.html.
This message may be cited.
GCN Circular 7011
Subject
GRB 071025: Kuiper Telescope Optical Observations
Date
2007-10-27T19:49:05Z (18 years ago)
From
Grant Williams at Steward Observatory <ggwilli@gmail.com>
P. A. Milne (Steward Observatory) and G. G. Williams (MMTO), on behalf of the
Super-LOTIS Collaboration, report:
The 1.54m Kuiper telescope began observations of the error region of
GRB 071025 (Swift trigger 295301, Pagani et al. GCN 6986) at 04:37:08
UT, approximately 28 minutes after the trigger. Observations were
obtained in the V, R, and I-bands. The afterglow first reported by
Rykoff et al. (GCN 6987) is clearly visible in the individual early R
and I band images but not in the V-band images or in the sum of the
V-band images. Observations continued until 09:47:09 UT.
The aperture photometry results below were obtained from sums of
individual images using nearby stars in the USNO-B1.0 and NOMAD
catalogs. Further analysis of additional epochs is continuing.
Filter UT-Start UT-End exp (s) magnitude error
R ---- 04:37:08 ----- 04:41:30 ---- 150 --- 18.7 +/- 0.1
R ---- 04:42:14 ----- 05:02:40 ---- 1080 -- 19.3 +/- 0.1
R ---- 05:03:12 ----- 05:24:11 ---- 1080 -- 19.8 +/- 0.1
V ---- 05:43:38 ----- 06:07:46 ---- 1200 -- < 22.0
I ---- 05:25:05 ----- 05:42:39 ---- 960 -- 18.2 +/- 0.1
I ---- 08:01:20 ----- 08:55:41 ---- 3000 -- 19.9 +/- 0.15
This message may be cited.
GCN Circular 7018
Subject
GRB071025: Optical+NIR observations
Date
2007-10-29T23:02:05Z (18 years ago)
From
Paul Price at IfA,UH <price@ifa.hawaii.edu>
T. Minezaki (IoA, Tokyo), P.A. Price (IfA, Hawaii), Y. Yoshii (IoA,
Tokyo), L. Cowie (IfA, Hawaii) and Y. Kakazu (IfA, Hawaii) report:
We observed the optical afterglow of GRB071025 with the robotic MAGNUM
telescope + MIPS dual-beam imager. We find a fading source in each of
the RIYJHK bands at the position reported by Bloom et al. (GCN 6989):
Filter midtime(UTC) Exp. time magnitude/upper limits
J 2007-10-25 06:59 10 17.73 +- 0.06
R 2007-10-25 07:01 10 21.5 +- 0.4
Y 2007-10-25 07:21 9 detected
I 2007-10-25 07:21 10 19.97 +- 0.13
K 2007-10-25 07:43 8 16.67 +- 0.07
R 2007-10-25 07:43 10 > 20.9
H 2007-10-25 08:04 9 17.59 +- 0.08
I 2007-10-25 08:04 10 20.3 +- 0.2
J 2007-10-25 08:25 9 18.29 +- 0.10
R 2007-10-25 08:25 10 > 21.0
Y 2007-10-25 08:44 9 marginally detected
I 2007-10-25 08:44 10 20.5 +- 0.3
The magnitude and the 3-sigma upper limits were derived using the
USNO-B1.0 and 2MASS catalogues. The magnitude error does not include the
error of the calibration source. The Y-band observations have not been
calibrated.
This message may be cited.