arXiv subjects

Jielai Zhang

Publications and source records attributed to Jielai Zhang.

At least 19 recordsLinked to original sources

arXiv2026

The Deeper, Wider, Faster programme's first DECam optical data release

The transient and variable optical sky is relatively poorly characterised on fast ($<$1$\,$hr) timescales. With the Dark Energy Camera (DECam), the Deeper, Wider, Faster programme (DWF) probes a unique parameter space with its deep (median of $g\sim22.2$ AB mag), minute-cadence imaging. In this work, we present DWF's first data release which comprises high cadence photometry extracted from $\sim$12000 images and 166 hours of telescope time. We present a novel data processing pipeline, $\texttt{dwf-postpipe}$, developed to identify sources and extract their light curves. The accuracy of the photometry is assessed by cross-matching to public catalogues. In addition, we injected a population of synthetic GRB afterglows into a subset of the DWF DECam imaging to compare the efficiency of our pipeline with a standard difference imaging approach. Both pipelines show performance and reliably recover injected transients with peak magnitudes $g<22$ AB mag with an efficiency of $97.24^{+0.7}_{-1.0}$ percent for \texttt{dwf-postpipe} and $96.14^{+0.9}_{-1.1}$ percent for a difference imaging approach. However, we find that $\texttt{dwf-postpipe}$ is less likely to recover transients appearing in galaxies that are brighter or comparable in brightness to the transient itself. To demonstrate the power of the data in this release, we conduct a search for uncatalogued variable stars in a single night of DWF DECam imaging and find ten pulsating variables, two eclipsing binaries and one ZZ ceti. We also conduct a search for variable phenomena in the Chandra Deep Field South, a Rubin deep drilling field, and identify two flares from likely UV ceti type stars.

astro-ph.HE↗

arXiv2025

An extremely fast fading population II dwarf nova candidate: caught spectroscopically on the rise

We present AT2022kak, a rapidly evolving optical transient discovered by the KiloNova and Transients Program (KNTraP). This interesting burst exhibited extremely fast evolution, with a large amplitude blue outburst of m > 3.3 in a single night, and a rapid fade back to quiescence in the following two nights. We deployed a multi-wavelength follow-up campaign, monitoring the object for the next two months, but saw no recurrent burst. Three years later, while observing to get spectroscopy of the object in quiescence, there was a new outburst, enabling the collection of time-resolved spectra of the rise and fade of the outburst. The light curve properties of the first burst and spectra of the second burst are consistent with a dwarf nova. Its fast evolving behaviour makes it one of the fastest and faintest dwarf novae observed. The estimated distance of AT2022kak from the Galactic centre is ~6.6 kpc, with a scale height of ~2 kpc. This scale height places it in the Galactic thick disk, where only very few dwarf novae have been found, and is therefore a potential Population II dwarf novae system.

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arXiv2025

A Machine Learning empowered search for Sub-Minute Optical Transient Events with the Deeper, Wider, Faster programme

Optical transient surveys continue to generate increasingly large datasets, prompting the introduction of machine-learning algorithms to search for quality transient candidates efficiently. Existing machine-learning infrastructure can be leveraged in novel ways to search these datasets for new classes of transients. We present a machine-learning accelerated search pipeline for the Deeper, Wider, Faster (DWF) programme designed to identify high-quality astrophysical transient candidates that contain a single detection. Given the rapid observing cadence of the DWF programme, these single-detection transient candidates have durations on sub-minute timescales. This work marks the first time optical transients have been systematically explored on these timescales, to a depth of m$\sim$23. We report the discovery of two high-quality sub-minute transient candidates from a pilot study of 671,761 light curves and investigate their potential origins with multiwavelength data. We discuss, in detail, possible non-astrophysical false positives, confidently reject electronic artefacts and asteroids, ruling out glints from satellites below 800 km and strongly disfavouring those at higher altitudes. We calculate a rate on the sky of $4.72^{+6.39}_{-3.28}\times10^5$ per day for these sub-minute transient candidates.

astro-ph.IM↗

arXiv2025

FLIMFLAM DR1: The First Constraints on the Cosmic Baryon Distribution from 8 FRB sightlines

The dispersion measure of fast radio bursts (FRBs), arising from the interactions of the pulses with free electrons along the propagation path, constitutes a unique probe of the cosmic baryon distribution. Their constraining power is further enhanced in combination with observations of the foreground large-scale structure and intervening galaxies. In this work, we present the first constraints on the partition of the cosmic baryons between the intergalactic medium (IGM) and circumgalactic medium (CGM), inferred from the FLIMFLAM spectroscopic survey. In its first data release, the FLIMFLAM survey targeted galaxies in the foreground of 8 localized FRBs. Using Bayesian techniques, we reconstruct the underlying ~Mpc-scale matter density field that is traced by the IGM gas. Simultaneously, deeper spectroscopy of intervening foreground galaxies (at impact parameters $b_\perp \lesssim r_{200}$) and the FRB host galaxies constrains the contribution from the CGM. Applying Bayesian parameter inference to our data and assuming a fiducial set of priors, we infer the IGM cosmic baryon fraction to be $f_{\rm igm}=0.59^{+0.11}_{-0.10}$, and a CGM gas fraction of $f_{\rm gas} = 0.55^{+0.26}_{-0.29}$ for $10^{10}\,M_\odot \lesssim M_{\rm halo}\lesssim 10^{13}\,M_\odot$ halos. The mean FRB host dispersion measure (rest-frame) in our sample is $\langle \rm{DM_{host}}\rangle = 90^{+29}_{-19}\rm{pc~cm^{-3}}$, of which $\langle{\rm DM_{host}^{unk}}\rangle =69^{+28}_{-19}~\rm{pc~cm^{-3}}$ arises from the host galaxy ISM and/or the FRB progenitor environment. While our current $f_{\rm igm}$ and $f_{\rm gas}$ uncertainties are too broad to constrain most galactic feedback models, this result marks the first measurement of the IGM and CGM baryon fractions, as well as the first systematic separation of the FRB host dispersion measure into two components: arising from the halo and from the inner ISM/FRB engine.

astro-ph.GA↗

arXiv2025

A follow-up strategy enabling discovery of electromagnetic counterparts to highly-magnified gravitationally-lensed gravitational waves

Making an unambiguous detection of lensed gravitational waves is challenging with current generation detectors due to large uncertainties in sky localisations and other inferred parameter distributions. However, in the case of binary neutron star (BNS) mergers this challenge can be overcome by detecting multiple images of its lensed kilonova counterpart, simultaneously confirming the lensing nature of the event and locating it precisely - further enabling a wealth of lensed multimessenger science. Such a strategy demands answers to two key problems: 1) How can candidate lensed BNS events be identified fast enough to ensure the lensed kilonova is still detectable? 2) What is the most economical observing strategy on telescope time for following up candidate lensed events to discover lensed kilonovae? This article will discuss solutions to both points, specifically: how GW detections of progenitors in the $\sim$ 2.5 to 5 $M_\odot$ black hole "mass gap" can be interpreted as candidate lensed BNS events, giving evidence for lensing from just a single detection, and will present a strategy that can actively be employed for follow-up of such events in the O4 run of LVK and beyond.

astro-ph.HE↗

arXiv2025

GRB$\,$220831A: a hostless, intermediate Gamma-ray burst with an unusual optical afterglow

GRB$\,$220831A is a gamma-ray burst (GRB) with a duration and spectral peak energy that places it at the interface between the distribution of long-soft and short-hard GRBs. In this paper, we present the multi-wavelength follow-up campaign to GRB$\,$220831A and its optical, near-infrared, X-ray and radio counterparts. Our deep optical and near-infrared observations do not reveal an underlying host galaxy, and establish that GRB$\,$220831A is observationally hostless to depth, $m_i\gtrsim26.6$ AB mag. Based on the Amati relation and the non-detection of an accompanying supernova, we find that this GRB is most likely to have originated from a collapsar at $z>2$, but it could also possibly be a compact object merger at $z<0.4$ with a large separation distance from its host galaxy. Regardless of its origin, we show that its optical and near-infrared counterpart departs from the evolution expected from a forward shock dominated synchrotron afterglow, exhibiting a steep post-break temporal powerlaw index of $-3.83^{+0.62}_{-0.79}$, too steep to be the jet-break. By analysing a range of models, we find that the observed steep departure from forward shock closure relations is likely due to an internal process producing either a flare or a plateau.

astro-ph.HE↗

arXiv2024

An Optically Led Search for Kilonovae to z$\sim$0.3 with the Kilonova and Transients Program (KNTraP)

Compact binary mergers detectable in gravitational waves can be accompanied by a kilonova, an electromagnetic transient powered by radioactive decay of newly synthesised r-process elements. A few kilonova candidates have been observed during short gamma-ray burst follow-up, and one found associated with a gravitational wave detection, GW170817. However, robust kilonova candidates are yet to be found in un-triggered, wide-field optical surveys, that is, a search not requiring an initial gravitational wave or gamma-ray burst trigger. Here we present the first observing run for the Kilonova and Transients Program (KNTraP) using the Dark Energy Camera. The first KNTraP run ran for 11 nights, covering 31 fields at a nightly cadence in two filters. The program can detect transients beyond the LIGO/Virgo/KAGRA horizon, be agnostic to the merger orientation, avoid the Sun and/or Galactic plane, and produces high cadence multi-wavelength light curves. The data were processed nightly in real-time for rapid identification of transient candidates, allowing for follow-up of interesting candidates before they faded away. Three fast-rising candidates were identified in real-time, however none had the characteristics of the kilonova AT2017gfo associated with GW170817 or with the expected evolution for kilonovae from our fade-rate models. After the run, the data were reprocessed, then subjected to stringent filtering and model fitting to search for kilonovae offline. Multiple KNTraP runs (3+) are expected to detect kilonovae via this optical-only search method. No kilonovae were detected in this first KNTraP run using our selection criteria, constraining the KN rate to $R < 1.8\times10^{5}$ Gpc$^{-3}$ yr$^{-1}$.

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arXiv2024

FRB Line-of-sight Ionization Measurement From Lightcone AAOmega Mapping Survey: the First Data Release

This paper presents the first public data release (DR1) of the FRB Line-of-sight Ionization Measurement From Lightcone AAOmega Mapping (FLIMFLAM) Survey, a wide field spectroscopic survey targeted on the fields of 10 precisely localized Fast Radio Bursts (FRBs). DR1 encompasses spectroscopic data for 10,468 galaxy redshifts across 10 FRBs fields with z<0.4, covering approximately 26 deg^2 of the sky in total. FLIMFLAM is composed of several layers, encompassing the `Wide' (covering ~ degree or >10 Mpc scales), `Narrow', (several-arcminute or ~ Mpc) and integral field unit (`IFU'; ~ arcminute or ~ 100 kpc ) components. The bulk of the data comprise spectroscopy from the 2dF-AAOmega on the 3.9-meter Anglo-Australian Telescope, while most of the Narrow and IFU data was achieved using an ensemble of 8-10-meter class telescopes. We summarize the information on our selected FRB fields, the criteria for target selection, methodologies employed for data reduction, spectral analysis processes, and an overview of our data products. An evaluation of our data reveals an average spectroscopic completeness of 48.43%, with over 80% of the observed targets having secure redshifts. Additionally, we describe our approach on generating angular masks and calculating the target selection functions, setting the stage for the impending reconstruction of the matter density field.

astro-ph.GA↗

arXiv2024

A Fast-cadenced Search for Gamma-Ray Burst Orphan Afterglows with the Deeper, Wider, Faster Programme

The relativistic outflows that produce Long GRBs (LGRBs) can be described by a structured jet model where prompt $γ$-ray emission is restricted to a narrow region in the jet's core. Viewing the jet off-axis from the core, a population of afterglows without an associated GRB detection can be predicted. In this work, we conduct an archival search for these `orphan' afterglows (OAs) with minute-cadence, deep ($g\sim23$) data from the Dark Energy Camera (DECam) taken as part of the Deeper, Wider, Faster programme (DWF). We introduce a method to select fast-evolving OA candidates within DWF data that comprises a machine learning model, based on a realistic synthetic population of OAs. Using this classifier, we recover 51 OA candidates. Of these candidates, 42 are likely flare events from M-class stars. The remaining nine possess quiescent, coincident sources in archival data with angular profiles consistent with a star and are inconsistent with the expected population of LGRB host galaxies. We therefore conclude that these are likely Galactic events. We calculate an upper limit on the rate of OAs down to $g<22$ AB mag of 7.46\,deg$^{-2}$yr$^{-1}$ using our criteria and constrain possible jet structures. We also place an upper limit of the characteristic angle between the $γ$-ray emitting region and the jet's half opening angle. For a smooth power-law and a power-law with core jet model respectively, these values are $58.3^{\circ}$ and $56.6^{\circ}$, for a power-law index of 0.8 and $75.3^{\circ}$ and $76.8^{\circ}$ for a power-law index of 1.2.

astro-ph.HE↗

arXiv2023

The FRB20190520B Sightline Intersects Foreground Galaxy Clusters

The repeating fast radio burst FRB20190520B is an anomaly of the FRB population thanks to its high dispersion measure (DM$=1205\,$pc/cc) despite its low redshift of $z_\mathrm{frb}=0.241$. This excess has been attributed to a large host contribution of $DM_{host}\approx 900\,$pc/cc, far larger than any other known FRB. In this paper, we describe spectroscopic observations of the FRB20190520B field obtained as part of the FLIMFLAM survey, which yielded 701 galaxy redshifts in the field. We find multiple foreground galaxy groups and clusters, for which we then estimated halo masses by comparing their richness with numerical simulations. We discover two separate $M_{halo} >10^{14}\,M_\odot$ galaxy clusters, at $z=0.1867$ and $z=0.2170$, respectively, that are directly intersected by the FRB sightline within their characteristic halo radius \rvir{}. Subtracting off their estimated DM contributions as well that of the diffuse intergalactic medium, we estimate a host contribution of $DM_{host}=430^{+140}_{-220}\,$pc/cc or $DM_{host}=280^{+140}_{-170}\,$pc/cc (observed frame) depending on whether we assume the halo gas extends to $r_{200}$ or $2\times r_{200}$. This significantly smaller $DM_{host}$ -- no longer the largest known value -- is now consistent with H$α$ emission measures of the host galaxy without invoking unusually high gas temperatures. Combined with the observed FRB scattering timescale, we estimate the turbulent fluctuation and geometric amplification factor of the scattering layer to be $\tilde{F} G\approx4.5 - 11\,(\mathrm{pc^2\;km})^{-1/3}$, suggesting most of the gas is close to the FRB host. This result illustrates the importance of incorporating foreground data for FRB analyses, both for understanding the nature of FRBs and to realize their potential as a cosmological probe.

astro-ph.GA↗

arXiv2023

A Recipe for Unbiased Background Modeling in Deep Wide-Field Astronomical Images

Unbiased sky background modeling is crucial for the analysis of deep wide-field images, but it remains a major challenge in low surface brightness astronomy. Traditional image processing algorithms are often designed to produce artificially flat backgrounds, erasing astrophysically meaningful structures. In this paper, we present three ideas that can be combined to produce wide-field astronomical data that preserve accurate representations of the background sky: (1) Use of all-sky infrared/sub-mm data to remove the large-scale time-varying components while leaving the scattered light from Galactic cirrus intact, with the assumptions of (a) the underlying background has little power on small scales, and (b) the Galactic cirrus in the field is optically thin on large scales; (2) Censoring of frames contaminated by anomalously prominent wings in the wide-angle point-spread function; and (3) Incorporation of spatial covariance in image stacking that controls the local background consistency. We demonstrate these methods using example datasets obtained with the Dragonfly Telephoto Array, but these general techniques are prospective to be applied to improve sky models in data obtained from other wide-field imaging surveys, including those from the upcoming Vera Rubin Telescope.

astro-ph.IM↗

arXiv2023

Joint Modelling of Dust Scattering and Thermal Emission: The Spider Complex

Observations across the electromagnetic spectrum of radiative processes involving interstellar dust -- emission, extinction, and scattering -- are used to constrain the parameters of dust models and more directly to aid in foreground removal of dust for extragalactic and cosmology observations. The more complementary observations, the better. Here, we quantify the relationship between scattered light and thermal emission from dust in a diffuse (cirrus) intermediate latitude cloud, Spider, using data from the Dragonfly Telephoto Array and the Herschel Space Observatory. A challenge for optical observations of faint cirrus is accurate removal of a contaminating spatially varying sky background. We present a technique to analyse two images of the same cirrus field concurrently, correlating pixel values to capture the relationship and simultaneously fitting the sky background as a complex non-correlating additive component. For the Spider, we measure a $g-r$ color of 0.644$\pm 0.024$ and a visible wavelength to 250 $μ$m intensity ratio of $10^{-3} \times (0.855 \pm0.025)$ and $10^{-3} \times (1.55\pm0.08)$ for $g$ and $r$-band respectively. We show how to use any dust model that matches the thermal dust emission to predict an upper limit to the amount of scattered light. The actual brightness of the cirrus will be fainter than this limit because of anisotropic scattering by the dust combined with anisotropy of the incident interstellar radiation field (ISRF). Using models of dust and the ISRF in the literature we illustrate that the predicted brightness is indeed lower, though not as faint as the observations indicate.

astro-ph.GA↗

arXiv2023

Searching for the sources of excess extragalactic dispersion of FRBs

The FLIMFLAM survey is collecting spectroscopic data of field galaxies near fast radio burst (FRB) sightlines to constrain key parameters describing the distribution of matter in the Universe. In this work, we leverage the survey data to determine the source of the excess extragalactic dispersion measure (DM), compared to the Macquart relation estimate of four FRBs: FRB20190714A, FRB20200430A, FRB20200906A, and FRB20210117A. By modeling the gas distribution around the foreground galaxy halos and galaxy groups of the sightlines, we estimate $\rm DM_{halos}$, their contribution to the FRB dispersion measures. The FRB20190714A sightline shows a clear excess of foreground halos which contribute roughly 2/3$^{rd}$ of the observed excess DM, thus implying a baryon-dense sightline. FRB20200906A shows a smaller but non-negligible foreground halo contribution, and further analysis of the IGM is necessary to ascertain the true cosmic contribution to its DM. RB20200430A and FRB20210117A show negligible foreground contributions, implying a large host galaxy excess and/or progenitor environment excess.

astro-ph.GA↗

arXiv2022

A very luminous jet from the disruption of a star by a massive black hole

Tidal disruption events (TDEs) are bursts of electromagnetic energy released when supermassive black holes (SMBHs) at the centers of galaxies violently disrupt a star that passes too close. TDEs provide a new window to study accretion onto SMBHs; in some rare cases, this accretion leads to launching of a relativistic jet, but the necessary conditions are not fully understood. The best studied jetted TDE to date is Swift J1644+57, which was discovered in gamma-rays, but was too obscured by dust to be seen at optical wavelengths. Here we report the optical discovery of AT2022cmc, a rapidly fading source at cosmological distance (redshift z=1.19325) whose unique lightcurve transitioned into a luminous plateau within days. Observations of a bright counterpart at other wavelengths, including X-rays, sub-millimeter, and radio, supports the interpretation of AT2022cmc as a jetted TDE containing a synchrotron "afterglow", likely launched by a SMBH with spin $a \gtrsim 0.3$. Using 4 years of Zwicky Transient Facility (ZTF) survey data, we calculate a rate of $0.02 ^{+ 0.04 }_{- 0.01 }$ Gpc$^{-3}$ yr$^{-1}$ for on-axis jetted TDEs based on the luminous, fast-fading red component, thus providing a measurement complementary to the rates derived from X-ray and radio observations. Correcting for the beaming angle effects, this rate confirms that about 1% of TDEs have relativistic jets. Optical surveys can use AT2022cmc as a prototype to unveil a population of jetted TDEs.

astro-ph.HE↗

arXiv2022

A giant shell of ionized gas discovered near M82 with the Dragonfly Spectral Line Mapper pathfinder

We present the discovery of a giant cloud of ionized gas in the field of the starbursting galaxy M82. Emission from the cloud is seen in H$α$ and [NII]$λ$6583 in data obtained though a small pathfinder instrument used to test the key ideas that will be implemented in the Dragonfly Spectral Line Mapper, an upcoming ultranarrow-bandpass imaging version of the Dragonfly Telephoto Array. The discovered cloud has a shell-like morphology with a linear extent of $0.8^{\circ}$ and is positioned $0.6^{\circ}$ northwest of M82. At the heliocentric distance of the M81 group, the cloud's extent corresponds to 55 kpc and its projected distance from the nucleus of M82 is 40 kpc. The cloud has an average H$α$ surface brightness of $2\times10^{-18}$ $\mathrm{erg} ~\mathrm{cm}^{-2} ~\mathrm{s}^{-1} ~\mathrm{arcsec}^{-2}$. The [NII]$λ$6583/H$α$ line ratio varies from [NII]/H$α$ $\sim0.2$ to [NII]/H$α$ $\sim1.0$ across the cloud, with higher values found in its eastern end. Follow-up spectra obtained with Keck-LRIS confirm the existence of the cloud and yield line ratios of [NII]$λ$6583/H$α$ = 0.340 $\pm$ 0.003 and [SII]$λ$6716,6731/H$α$ = 0.64 $\pm$ 0.03 in the cloud. This giant cloud of material could be lifted from M82 by tidal interactions or by its powerful starburst. Alternatively, it may be gas infalling from the cosmic web, potentially precipitated by the superwinds of M82. Deeper data are needed to test these ideas further. The upcoming Dragonfly Spectral Line Mapper will have 120 lenses, $40\times$ more than in the pathfinder instrument used to obtain the data presented here.

astro-ph.GA↗

arXiv2022

Constraining the Cosmic Baryon Distribution with Fast Radio Burst Foreground Mapping

The dispersion measures (DM) of fast radio bursts (FRBs) encode the integrated electron density along the line-of-sight, which is typically dominated by the intergalactic medium (IGM) contribution in the case of extragalactic FRBs. In this paper, we show that incorporating wide-field spectroscopic galaxy survey data in the foreground of localized FRBs can significantly improve constraints on the partition of diffuse cosmic baryons. Using mock DMs and realistic lightcone galaxy catalogs derived from the Millennium simulation, we define spectroscopic surveys that can be carried out with 4m and 8m-class wide field spectroscopic facilities. On these simulated surveys, we carry out Bayesian density reconstructions in order to estimate the foreground matter density field. In comparison with the `true' matter density field, we show that these can help reduce the uncertainties in the foreground structures by $\sim 2-3\times$ compared to cosmic variance. We calculate the Fisher matrix to forecast that $N=30\: (96)$ localized FRBs should be able to constrain the diffuse cosmic baryon fraction to $\sim 10\%\: (\sim 5\%) $, and parameters governing the size and baryon fraction of galaxy circumgalactic halos to within $\sim 20-25\%\: (\sim 8-12\%)$. From the Fisher analysis, we show that the foreground data increases the sensitivity of localized FRBs toward our parameters of interest by $\sim 25\times$. We briefly introduce FLIMFLAM, an ongoing galaxy redshift survey that aims to obtain foreground data on $\sim 30$ localized FRB fields.

astro-ph.CO↗

arXiv2021

A Nascent Tidal Dwarf Galaxy Forming within the Northern HI Streamer of M82

We identify a $\sim$600 pc-wide region of active star formation located within a tidal streamer of M82 via $Hα$ emission ($F_{Hα}\sim 6.5\times10^{-14}$ erg s$^{-1}$ cm$^{-2}$), using a pathfinder instrument based on the Dragonfly Telephoto Array. The object is kinematically decoupled from the disk of M82 as confirmed via Keck / LRIS spectroscopy, and is spatially and kinematically coincident with an overdensity of HI and molecular hydrogen within the "northern HI streamer" induced by the passage of M81 several hundred Myr ago. From HI data, we estimate that $\sim5\times10^7$ M$_{\odot}$ of gas is present in the specific overdensity coincident with the $Hα$ source. The object's derived metallicity (12+$\log(O/H)\simeq 8.6$), position within a gas-rich tidal feature, and morphology (600 pc diameter with multiple star forming clumps), indicate that it is likely a tidal dwarf galaxy in the earliest stages of formation.

astro-ph.GA↗

arXiv2021

Finding Fast Transients in Real Time Using Novel Light Curve Analysis Algorithm

The current data acquisition rate of astronomical transient surveys and the promise for significantly higher rates during in the next decade necessitate the development of novel approaches to analyze astronomical data sets and promptly detect objects of interest. The Deeper, Wider, Faster (DWF) program is a survey focused on the identification of fast evolving transients, such as fast radio bursts, gamma-ray bursts, and supernova shock breakouts. It employs a multi-frequency simultaneous coverage of the same part of the sky over several orders of magnitude. Using the Dark Energy Camera mounted on the 4-meter Blanco telescope, DWF captures a 20 second g-band exposure every minute, at a typical seeing of ~ 1" and an airmass of ~ 1.5. These optical data are collected simultaneously with observations conducted over the entire electromagnetic spectrum - from radio to gamma-rays - as well as cosmic ray observations. In this paper, we present a novel real-time light curve analysis algorithm, designed to detect transients in the DWF optical data; this algorithm functions independently from, or in conjunction with, image subtraction. We present a sample of fast transients detected by our algorithm, as well as a false-positive analysis. Our algorithm is customizable and can be tuned to be sensitive to transients evolving over different timescales and flux ranges.

astro-ph.IM↗