GRB 240209A
GCN Circular 35751
Subject
IPN triangulation of GRB 240209A
Date
2024-02-18T17:22:41Z (2 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
Via
legacy email
D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,
and
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team,
report:
The long-duration GRB 240209A
(Fermi-GBM detection: The Fermi GBM team, GCN 35712;
Malacaria et al., GCN 35729)
was detected by Fermi (GBM trigger 729152364) and
Konus-Wind, in the waiting mode, at about 22760 s UT (06:19:20).
We have triangulated it to a Konus-GBM annulus centered at
RA(2000)=119.672 deg (07h 58m 41s) Dec(2000)=+19.090 deg (+19d 05' 25"),
whose radius is 66.074 +/- 14.729 deg (3 sigma).
The annulus combined with the Fermi-GBM final position (GCN 35712;
glg_healpix_all_bn240209263_v01) gives ~2019 sq. deg (3 sigma) localization region.
The reported optical counterpart candidate GOTO24pw/AT2024cew
(Belkin et al., GCN 35715) is outside the Konus-GBM annulus,
implying that the optical transient is unrelated to the GRB.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB240209_T22759/IPN
GCN Circular 35730
Subject
GRB 240209A: Classification of AT2024cew/GOTO24pw as Type Ia-pec supernova
Date
2024-02-14T22:00:51Z (2 years ago)
From
kendall.ackley@warwick.ac.uk
Via
Web form
K. Ackley; D. Steeghs; B. P. Gompertz; M. Magee; J. Lyman; R. Starling; M. J. Dyer; K. Ulaczyk; F. Jimenez-Ibarra; A. Kumar; D. O'Neill; D. K. Galloway; V. Dhillon; P. O'Brien; G. Ramsay; K. Noysena; R. Kotak; R. P. Breton; L. K. Nuttall; E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration and the GOTO-FAST program:
We report on the classification of AT2024cew/GOTO24pw as part of the GOTO-FAST program (Godson et al., https://www.wis-tns.org/astronotes/astronote/2023-224). The source was first reported by GOTO (Belkin et al, GCN 35715) as a possible optical counterpart to GRB 240209A (Fermi GBM team, GCN 35712). It showed an initial decline across the GOTO epochs which was consistent with the ZTF photometry obtained through the Lasair broker (Smith et al. 2019).
Following the reported brightening of the source (de Ugarte Postigo et al., GCN 35716) we obtained spectroscopic observations on the night of 2024-02-13 with the Isaac Newton Telescope (INT) using the IDS spectrograph with R150V grating (3950-7900 A, R~600). The INT spectrum is consistent with a Type Ia-pec SN at a redshift of z=0.15 (Godson et al. 2024, https://www.wis-tns.org/astronotes/astronote/2024-52). AT2024cew is therefore unrelated to GRB 240209A.
At this distance, the ongoing brightening measured by NOT (de Ugarte Postigo et al., GCN 35716), Wendelstein (Busmann et al., GCN 35724), and OHP (Turpin et al., GCN 35725) implies an absolute magnitude of -19.5. This is luminous for normal type Ia SNe and is consistent with peculiar SN Ia classification.
Based on observations made with the Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.
GCN Circular 35729
Subject
GRB 240209A: Fermi GBM observation
Date
2024-02-14T21:34:38Z (2 years ago)
From
Christian Malacaria at ISSI <cmalacaria.astro@gmail.com>
Via
Web form
C. Malacaria (ISSI) reports on behalf of the Fermi GBM Team:
"At 06:19:19.82 UT on 09 February 2024, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 240209A (GCN #35712).
A GOTO optical counterpart candidate was found
within the GBM 90% localisation region (GCN #35715), at a nominal
angular separation from the GBM on-ground localisation of 2.4 degrees.
Additional observations of the GOTO candidate
were reported in GCN #35716, #35717, #35724, #35725.
Careful inspection of the GBM trigger by the Fermi-GBM Team identified
a weak, soft GRB.
The GBM light curve consists of a single pulse with a duration (T90)
of about 5.4 s (50-300 keV). The time-averaged spectrum from
T0-4.0 s to T0+0.0 s is best fit by a power law function with
index of -1.82 +/- 0.07
A power law function with an exponential high-energy cutoff with
alpha = -1.4 +/- 0.2 and Epeak = 107 +/- 40 keV,
fits the spectrum equally well.
The event fluence (10-1000 keV) in this time interval is
(7.0 +/- 0.8)E-07 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0-1.98 s in the 10-1000 keV band
is 3.0 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 35725
Subject
GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
Date
2024-02-14T17:57:42Z (2 years ago)
From
Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>
Via
Web form
D. Turpin (CEA Paris-Saclay), C. Adami (LAM), A. de Ugarte Postigo (CNRS/OCA & LAM), E. Le Floc'h, D. Götz, F. Schüssler (CEA Paris-Saclay), B. Schneider (MIT), S. Basa (Pytheas/OHP/LAM), J. T. Palmerio, A. Saccardi, S. D. Vergani (GEPI, Obs. de Paris), report on behalf of a larger collaboration:
We observed the optical afterglow candidate of GRB 240209A (Fermi GBM team, GCN 35343) reported by the GOTO team (Belkin et al. GCN 35715) and also followed-up by the NOT and Wendelstein telescopes (de Ugarte Postigo et al. GCN 35716, Busmann et al. GCN 25724) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL instrument. We took two series of r-band and g-band images (3x10min for each band) starting at 2024-02-14 04:00:34 UT. In both single and combined frames we detect the optical source at a high S/N. We performed forced photometry at the position of the source both on the science and difference image (we used PanSTARRS template images to make the subtraction) as the close HyperLEDA 2722973 galaxy might affect our measure. We derived the following magnitudes :
----------------------------------------------------------
T-T0 (in days, midtime) | mag | filter | subtracted
----------------------------------------------------------
4.893 | 20.06 ± 0.03 mag (AB) | r' | y
4.893 | 19.41 ± 0.02 mag (AB) | r' | n
4.919 | 20.02 ± 0.01 mag (AB) | g' | y
4.919 | 19.78 ± 0.01 mag (AB) | g' | n
-----------------------------------------------
The photometric calibration was performed using nearby stars from the PanSTARRS catalog and magnitudes are not corrected for Galactic extinction and the uncertainties are statistical only.
We note that our residual image magnitudes suggest a fading behavior of the source with respect to the NOT and the Wendelstein r-band epochs while the forced photometry on science images is in very good agreement with them. Further investigations about the potential flux contamination due to the presence of the HyperLEDA 2722973 galaxy will be done.
In addition to our photometric observations, we also performed spectroscopic observations of the source and the HyperLEDA 2722973 galaxy with the blue mode of MISTRAL. A total exposure of 20 minutes was obtained.
The preliminary analysis of the spectrum of the source suggests a rather blue transient (in agreement with the g-r ~ -0.04 we measured from difference image analysis) but at odds with typical GRB afterglow red colors. Due to the low S/N of the spectrum, we did not identify clear spectral features to estimate a redshift.
The MISTRAL spectrum of the HyperLEDA 2722973 galaxy shows a clear absorption complex that could be identified with the 5175A/5269A lines. This would suggest a redshift of z~0.207, close to the photometric value of z=0.1629+/-0.0150.
Further observation will be taken on Saturday night at OHP (weather permitting) to better characterize the color evolution of this transient.
We acknowledge the excellent support from Observatoire de Haute-Provence, in particular Stéphane Favard for the MISTRAL observations and the SOPHIE observer Magali Deleuil.
GCN Circular 35724
Subject
GRB 240209A: Wendelstein Optical Observations
Date
2024-02-14T10:42:16Z (2 years ago)
From
Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann@physik.lmu.de>
Via
Web form
Malte Busmann (LMU), Daniel Gruen (LMU), Brendan O’Connor (CMU), Antonella Palmese (CMU), Lei Hu (CMU), Arno Riffeser (LMU/MPE) report:
We observed the position of the optical afterglow candidate (AT2024cew / GOTO24pw; Belkin et al. GCN 35715; de Ugarte Postigo et al. GCN 35716) for GRB 240209A (Fermi GBM team, GCN 35712) with the 2.1 m Fraunhofer telescope at Wendelstein Observatory, Germany. Observations were obtained using the 3kk imager in the r, i, and J bands simultaneously, starting at 2024-02-13 at 17:42 UT, and again in the g, i and J bands, starting at 04:46 UT.
At the position of the transient (Belkin et al. GCN 35715), we clearly detect the source in g-band, r-band and i-band in the individual epochs. We measure a brightness of r~19.5+/-0.1 AB mag calibrated to the PS1 catalog. We marginally detect it in J-band co-adding both epochs, at J~20.2+/-0.4 calibrated to the 2MASS catalog. Compared to previous NOT r-band photometry (de Ugarte Postigo et al. GCN 35716) this represents an increase in brightness, further suggesting that this transient is unlikely to be associated with the GRB, as does the blue color r-i~0.3 mag.
Further observations to uncover the nature of the transient are encouraged.
We thank the staff of the Wendelstein Observatory for obtaining these observations.
GCN Circular 35717
Subject
GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
Date
2024-02-13T18:24:21Z (2 years ago)
From
Antonio de Ugarte Postigo at OCA <deugarte@oca.eu>
Via
email
A. de Ugarte Postigo (CNRS/OCA & LAM), M. Bremer (IRAM), C. C. Thoene (ASU-CAS), J. F. Agui Fernandez (CAHA), S. Antier (OCA), S. Basa (LAM), M. Michalowski (AOI-AMU), D. A. Perley (LJMU), S. Martin (ESO, ALMA) report:
We observed AT2024cew / GOTO24pw (Belkin et al. GCN 35715, de Ugarte Postigo et al. GCN 35716), the optical counterpart candidate of GRB 240209A (Fermi GBM team, GCN 35712), with NOEMA at 74 and 90 GHz at a mean epoch 4.025 days after the burst.
There is no detection down to a 3-sigma limit of 60 microJy at 90 GHz. This limit disfavours the connection between AT2024cew / GOTO24pw and GRB 240209A, although it is not excluding.
Based on observations carried out under project number W23DI with the IRAM NOEMA Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).
GCN Circular 35716
Subject
GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
Date
2024-02-13T17:19:17Z (2 years ago)
From
Antonio de Ugarte Postigo at OCA <deugarte@oca.eu>
Via
email
A. de Ugarte Postigo (CNRS/OCA & LAM), D. B. Malesani (DAWN/NBI & Radboud Univ.), M. I. Andersen (NBI), J. Sollerman (SU) report:
We observed AT2024cew / GOTO24pw (Belkin et al. GCN 35715), the optical counterpart candidate of GRB 240209A (Fermi GBM team, GCN 35712), using AlFOSC imaging on the 2.5m Nordic Optical Telescope (NOT), at the Roque de los Muchachos Observatory (La Palma, Spain).
The observation consisted of 5x300 s using r-band filter, with a mean time 3.990 days after the burst. The image shows a strong detection of the proposed counterpart at a preliminary magnitude of r~19.80+/-0.05, as compared to PanSTARRS field stars.
This is brighter than the last reported GOTO magnitude observed a day before, corresponding to a behaviour unlike typical GRB afterglows. However, we do note that there is a difference in the filters that could account for some inconsistency in the magnitudes of the two instruments.
If the object is at the same redshift of the nearby galaxy (photo-z = 0.16), then its absolute magnitude would be M_V ~ -19.9. This would be similar to some luminous supernovae (f.ex. a SN Ia) close to peak light. However, the fast decay and subsequent re-brightening in a day-scale, would be peculiar for a SN near peak.
GCN Circular 35715
Subject
GRB 240209A: GOTO optical counterpart candidate
Date
2024-02-12T11:09:24Z (2 years ago)
From
Sergey Belkin at Monash University <sergey.belkin@monash.edu>
Via
Web form
S. Belkin, M. Kennedy, B. P. Gompertz, K. Ackley, R. Starling, T. Killestein, M. J. Dyer, J. Lyman, K. Ulaczyk, F. Jimenez-Ibarra, A. Kumar, D. O'Neill, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration:
We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) in response to GRB 240209A (Fermi GBM team, GCN 35712). Targeted observations were performed by GOTO-North between 05:27:38 on 2024-02-11 (starting 47 hrs after trigger) and 03:58:21 on 2024-02-12. Each observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm).
Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using recent survey observations of the same pointings. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogues. Human vetting was carried out in real time on any candidates that passed the above checks.
We identify 1 candidate optical counterpart (GOTO24pw/AT2024cew) within the GBM 90% localisation region. We find no evidence of this source prior to the GRB trigger time in previous GOTO observations, the ZTF observations provided by the Lasair broker (Smith et al. 2019), or the ATLAS forced photometry server (Shingles et al. 2021). The most recent non-detection was taken by ATLAS on 2024-02-01.
Name | RA(J2000) | Dec(J2000) | Filter | t - trig(days) | Mag(AB)
GOTO24pw | 17:01:05.29 | +68:43:46.31 | L | 1.96 | 19.64 +/- 0.14
The source is seen to decay as a power-law with an index of t^-1.80+/-0.16 across 3 epochs of observations. The most recent detection magnitude was L = 20.45 +/- 0.19 at 2.90 days after trigger.
Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.
We note the presence of the GLADE+ (Dalya et al. 2022) catalogued galaxy HyperLEDA 2722973 (z=0.1629+/-0.0150) approximately 7.3" away. At this redshift the sky-projected offset of the transient from this galaxy is 20.58 kpc. This transient is spatially coincident with the cluster ZwCl 8111.
Observations are ongoing.
GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).
GCN Circular 35712
Subject
GRB 240209A: Fermi GBM Final Localization
Date
2024-02-09T21:46:46Z (2 years ago)
From
Christian Malacaria at ISSI <cmalacaria.astro@gmail.com>
Via
Web form
The Fermi GBM team reports the detection of a likely LONG GRB.
"At 06:19:19.82 UT on 09 April 2024, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 240209A (trigger 729152364 / 240209263).
The on-ground calculated location, using the GBM trigger data,
is RA = 259.8, DEC = 70.5 (J2000 degrees, equivalent
to 17h 19m, 70d 30'), with an uncertainty of 9.1 degrees.
The angle from the Fermi LAT boresight at the GBM trigger time is 31 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240209263/quicklook/glg_skymap_all_bn240209263.png
The HEALPix FITS file, including the estimated localization systematic, can
be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240209263/quicklook/glg_healpix_all_bn240209263.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240209263/quicklook/glg_lc_medres34_bn240209263.gif"