ZTF23aabmzlp
GCN Circular 33229
Subject
ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
Date
2023-01-28T18:10:55Z (2 years ago)
From
Igor Andreoni at JSI <igor.andreoni@gmail.com>
Igor Andreoni (JSI), Harsh Kumar (IITB), Michael Coughlin (UMN), Gaurav
Waratkar (IITB), Eric Burns (LSU), Daniel Perley (LJMU)
We report the discovery of the very fast optical transient
ZTF23aabmzlp/AT2023azs with the Zwicky Transient Facility (ZTF, Bellm et
al. 2019, Graham et al. 2019) at coordinates:
RA = 11:30:16.49 (172.5687149d)
Dec = +65:51:10.01 (65.8527808d)
ZTF23aabmzlp was first detected on 2023-01-28 06:14 UT at r = 17.42 �� 0.04
mag. ZTF23aabmzlp faded by 2.3 magnitudes in 6.2 hours in the r-band. The
last ZTF upper limit before the first detection was measured on 2023-01-28
05:55 UT in g-band, which is about 19 minutes before the first detection.
There is no pre-detection at the transient location in 1,736 images of the
field previously acquired by the ZTF survey. ZTF photometry is reported in
the following table:
----------------------------------
MJD | mag AB
----------------------------------
59972.24688660 | g > 19.7
59972.25979170 | r = 17.42 +- 0.04
59972.36381940 | g = 19.20 +- 0.11
59972.43465280 | g = 19.60 +- 0.15
59972.51854170 | r = 19.72 +- 0.20
----------------------------------
Extinction on the line of sight is negligible, with E(B-V)=0.01 mag. The
transient is located at high Galactic latitude b=49.2 deg. There is no
cataloged source at the transient location in deep Legacy Survey DR9 and
Pan-STARRS (Chambers et al., 2016) archival images.
No gamma-ray triggers have been reported so far in the time window between
the last ZTF upper limit and the first detection. However, it is possible
that ZTF23aabmzlp/AT2023azs is a relativistic afterglow.
Follow-up observations are strongly encouraged.
ZTF23aabmzlp was discovered by the ������ZTF Realtime Search and Triggering������
project (ZTFReST; Andreoni & Coughlin et al., 2021) within the ZTF
Collaboration.
Based on observations obtained with the Samuel Oschin Telescope 48-inch and
the 60-inch Telescope at the Palomar Observatory as part of the Zwicky
Transient Facility project. ZTF is supported by the National Science
Foundation under Grant No. AST-2034437 and a collaboration including
Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center
at Stockholm University, the University of Maryland, Deutsches
Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of
Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin,
Lawrence Livermore National Laboratories, and IN2P3, France. Operations are
conducted by COO, IPAC, and UW.
GCN Circular 33230
Subject
ZTF23aabmzlp/AT2023azs: GIT confirmation of the likely afterglow
Date
2023-01-28T19:08:22Z (2 years ago)
From
Harsh Kumar at Indian Inst of Tech,Bombay <harshkosli13@gmail.com>
H. Kumar (IITB), V. Swain (IITB), R. Norbu (IAO), G. Waratkar (IITB), V.
Bhalerao (IITB), G. C. Anupama(IIA), S. Barway (IIA) report on behalf of
the GIT team:
We observed ZTF23aabmzlp/AT2023azs discovered by Zwicky Transient Facility
(Andreoni et al., GCN #33229), with 0.7m GROWTH-India Telescope (GIT). We
obtained three exposures of 300sec each in the g', r', and i' filters. We
clearly detected the candidate in our stacked images. The photometric
results follow as:-
-------------------------------------------------------------------
JD (mid) | Filter | Magnitude (AB) |
-------------------------------------------------------------------
2459973.224114 | g' | 20.48 +/- 0.07 |
2459973.235212 | r' | 20.31 +/- 0.06 |
2459973.248096 | i' | 19.79 +/- 0.20 |
-------------------------------------------------------------------
GIT observations imply that the source continues fading and is redder in
colour. Comparing our g' and r' observations with ZTF (Andreoni et al., GCN
#33229), we compute a power-law decay index of ~0.7, further strengthening
the claim that the candidate is an afterglow. Candidate follow-up is
encouraged. The magnitudes are calibrated against PanSTARRS DR1 (Chambers
et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT; Kumar et al. 2022
<https://iopscience.iop.org/article/10.3847/1538-3881/ac7bea>) is a 70-cm
telescope with a 0.7-degree field of view, set up by the Indian Institute
of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB)
with funding from DST-SERB and IUSSTF. It is located at the Indian
Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding
by the IITB alumni batch of 1994, which partially supports operations of
the telescope. Telescope technical details are available at
https://sites.google.com/view/growthindia/.
GCN Circular 33237
Subject
ZTF23aabmzlp/AT2023azs: 1.3m DFOT optical observations
Date
2023-01-30T19:26:14Z (2 years ago)
From
Rahul Gupta at ARIES, India <rahulbhu.c157@gmail.com>
Rahul Gupta, Amit K. Ror, S. B. Pandey, A. Aryan, A. Ghosh, Kiran Wani,
Dimple, and K. Misra (ARIES) report:
We observed the fast optical transient ZTF23aabmzlp/AT2023azs discovery by
Zwicky Transient Facility (Andreoni et al. 2023, GCN 33229) using the 1.3m
Devasthal Fast Optical Telescope (DFOT) located at the Devasthal
observatory of Aryabhatta Research Institute of Observational Sciences
(ARIES), Nainital, India. We have taken multiple frames having an exposure
time of 120 sec in the R filter. We stacked the images after the alignment.
We clearly detected the ZTF23aabmzlp/AT2023azs in the stacked image. The
estimated preliminary magnitude is the following:
Date_Start_UT T_start-T0 (days) Filter Exp time (sec) Magnitude
==============================================================
2023-01-28 18:42:44 ~0.52 R 120 sec*10 20.21
+/- 0.07
Where T0 is the ZTF first detection time of the transient. Our optical
detection is consistent with Kumar et al. 2023, GCN 33230. The temporal
decay behaviour of ZTF23aabmzlp/AT2023azs suggests an afterglow candidate,
although multiwavelength follow-up observations are required to confirm.
The magnitude is not corrected for the Galactic extinction in the direction
of the transient. Photometric calibration is performed using the standard
stars from the USNO-B1.0 catalog.
This circular may be cited.
GCN Circular 33239
Subject
ZTF23aabmzlp/AT2023azs: Mondy and AbAO optical observations
Date
2023-01-31T15:17:33Z (2 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
N. Pankov (HSE), A. Pozanenko (IKI), E. Klunko (ISTP), R. Ya.
Inasaridze (AbAO), and S. Belkin (IKI) report on behalf of GRB IKI FuN:
We observed the optical transient of ZZTF23aabmzlp/AT2023azs (Andreoni
et al., GCN 33229) with AZT-33IK telescope of Mondy observatory starting
on 2023-01-29 (UT) 21:25:32 and AS-32 Abastumani observatory (AbAO) on
2023-01-30 (UT) 17:04:08. We detect the transient (Andreoni et al., GCN
33229; Kumar et al., GCN 33230; Gupta et al., GCN 33237) with AZT-33IK
and obtained an upper limit with AS-32.
Preliminary photometry of the transient is following
Date UT start MJD Filter Exp. OT Err. UL Telescope
(mid, days) (s)
2023-01-29 21:25:32 59973.9136 R 30*120 21.63 0.11 23.2 AZT-33IK
2023-01-30 17:04:08 59974.7112 R 145*60 n/d n/d 20.3 AS-32
The photometry is based on the nearby USNO-B1.0 stars
USNO-B1.0
RA Dec R2
172.5551 65.8488 18.68
172.5424 65.7999 17.05
172.4866 65.8507 15.58
GCN Circular 33241
Subject
ZTF23aabmzlp/AT2023azs: LCOGT Optical Detection
Date
2023-01-31T20:23:25Z (2 years ago)
From
Robert Strausbaugh at University of Minnesota <rstrausb@umn.edu>
R. Strausbaugh (University of Minnesota), A. Cucchiara (NASA) report on
behalf of a larger collaboration:
We observed the ZTF23aabmzlp/AT2023azs (Andreoni et al., GCN 33229) field
with the LCOGT 1-meter Sinistro instrument at the McDonald Observatory, TX,
USA site, on January 29, from 09:46 to 10:02 UT (corresponding to 27.53 to
27.80 hours after ZTF first detection) with the SDSS r filter.
We performed a series of 3x300s exposures in r band. We marginally
(2-sigma) detect a source at the candidate coordinates with evidence for
continued fading from previous optical observations (Kumar et al., GCN
33230; Gupta et al., GCN 33237; Pankov et al., GCN 33239).
The following magnitude is calculated using the PanSTARRS catalog as
reference:
r = 22.07 +/- 0.13
These magnitudes are not corrected for galactic extinction.
GCN Circular 33251
Subject
ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
Date
2023-02-02T12:49:13Z (2 years ago)
From
Lauren Rhodes at Oxford <lauren.rhodes@physics.ox.ac.uk>
Lauren Rhodes (Oxford), Itai Sfaradi (HUJI), Joe Bright (Oxford), Rob Fender (Oxford), Assaf Horesh (HUJI), David Green (Cambridge), Paul Scott (Cambridge), David Titterington (Cambridge) report:
We observed the field of the candidate optical afterglow ZTF23aabmzlp (AT2023azs)
(Andreoni et al., GCN 33229) with the Arcminute Microkelvin Imager Large-Array (AMI-LA) at 15.5 GHz beginning at UT 00:29:41 on 02-02-2023 for a total of 4 hours. The flux standard 3c286 was used to calibrate the bandpass response and flux scale of the AMI-LA and J1048+7143 was used as an interleaved complex gain calibrator.
We do not detect any radio emission at the position reported in GCN 33229 and report a 3sigma upper limit of 128uJy/beam. Further observations are planned, and any future radio detection will be reported.
We thank the staff at the Mullard Radio Astronomy Observatory for carrying out these observations and operating the AMI-LA.
GCN Circular 33253
Subject
ZTF23aabmzlp/AT2023azs: VLA radio detection
Date
2023-02-02T16:00:45Z (2 years ago)
From
Daniel Perley at Liverpool JMU <d.a.perley@ljmu.ac.uk>
D. A. Perley (LJMU) reports on behalf of a larger collaboration:
We observed the location of the fast optical transient ZTF23aabmzlp/AT2023azs (Andreoni et al., GCN 33229) using the Karl G. Jansky Very Large Array (VLA) on 2023 January 31 between 04:49 and 05:23 (UT). Observations were carried out using the X-band receivers at a mean frequency of 10 GHz.
We detect a source at a location of RA = 11:30:16.468, Dec=+65:51:10.007 (J2000; RMS statistical accuracy +/- 0.02"), consistent with the optical position. The flux density is 136 (+/- 6) microJy at 9 GHz and 76 (+/- 7) microJy at 11 GHz. The mean observation time is approximately 59975.22, 2.96 days after the first reported optical detection.
The detection of radio emission supports the conclusion that the source is the afterglow of a relativistic explosion at cosmological distance. The unusual spectral index is likely due to interstellar scintillation.
We thank the VLA staff for rapidly scheduling and executing these observations.
DisclaimerNone
GCN Circular 33255
Subject
ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
Date
2023-02-03T15:40:58Z (2 years ago)
From
Ting-Wan Chen at MPE <janet.chen@astro.su.se>
S. Yang (Stockholm), T.-W. Chen (TUM/MPA), H.-Y. Hsiao, Y.-C. Pan, C.-C. Ngeow, W.-J. Hou, C.-S. Lin, H.-C. Lin, and J.-K. Guo (IANCU) report:
We observed the field of ZTF23aabmzlp/AT2023azs (Andreoni et al., GCN 33229), using the Lulin One-meter Telescope (LOT) at Lulin Observatory, Taiwan, to obtain g,r,i-band images as part of the Kinder collaboration (Chen et al., AstroNote 2021-92).
The first epoch of observations started at 20:51 UT on 28 of January 2023 (MJD = 59972.869), 0.61 days after the first detection from ZTF. The images were combined from 3 frames with 300 sec exposure time for g and r bands, and 2 frames with 300 sec exposure time for i band, taken under poor seeing conditions (4".0 average) and at a median airmass of 1.5. The second epoch was performed at 20:38 UT on 29 of January 2023 (MJD = 59973.860). The images were combined from 2 frames with 300 sec exposure time for each band, taken under variable seeing conditions (1".8 average) and at a median airmass of 1.5.
We used PSF photometry to measure the transient brightness with template subtraction using the SDSS images, and derived the following preliminary magnitudes and 3-sigma limits (all in the AB system):
2023-01-28:
g > 20.18 mag,
r > 19.21 mag, and
i > 19.13 mag.
2023-01-29:
g > 21.82 mag,
r = 21.78 +/- 0.15 mag, and
i = 21.34 +/- 0.13 mag.
Given magnitudes are calibrated against SDSS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.01 mag in the direction of the counterpart (Schlafly & Finkbeiner 2011).
Our measurements of the photometric evolution of ZTF23aabmzlp/AT2023azs are consistent with previous optical observations reported from Kumar et al., GCN 33230; Gupta et al., GCN 33237; Pankov et al., GCN 33239; Strausbaugh et al., GCN 33241.
GCN Circular 33297
Subject
ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
Date
2023-02-07T15:14:32Z (2 years ago)
From
Igor Andreoni at JSI <igor.andreoni@gmail.com>
Igor Andreoni (JSI/UMD/NASA-GSFC) reports on behalf of a larger
collaboration
Follow-up observations of the optical fast transient ZTF23aabmzlp/AT2023azs
(Andreoni et al., GCN #33229, AstroNote 2023-21) were carried out with the
Neil Gehrels Swift Observatory starting on 2023-01-29 09:54 UT. The total
exposure time on target was 1.9ks.
A faint source is tentatively detected in Swift XRT data at the location of
ZTF23aabmzlp/AT2023azs in the 0.3-10 keV energy range. The source has a
background-subtracted count rate of (2.5 +- 1.1) * 10^(-3) ct/s, which was
obtained using an aperture with a radius of 18 arcsec.
Using WebPIMMS [1], we converted the count rate to flux assuming a
powerlaw model with a photon index of 2 and Galactic NH of 9.85E19 cm^(-2)
[2]. The resulting flux in the 0.3-10 keV band is (8.6 +- 3.8) * 10^(-14)
erg/s/cm^2.
The possible detection of an X-ray counterpart and the detection of a radio
counterpart with VLA (Perley et al., GCN #33253) further suggest that the
fast optical transient ZTF23aabmzlp/AT2023azs is a cosmological afterglow.
We thank the Swift team for approving and scheduling ToO observations of
this source (target ID 15860).
[1] https://heasarc.gsfc.nasa.gov/cgi-bin/Tools/w3pimms/w3pimms.pl
[2] HI4PI Collaboration, N. Ben Bekhti, L. Floer, et al., 2016, Astronomy &
Astrophysics, 594, A116 (HI4PI Map).