GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"30476 results found.
- EP251124b: NOT r- and z-band optical upper limits
- Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
- Fermi GRB 251125B: Global MASTER-Net observations report
- EP251124b: Global MASTER-Net observations report
- EP251124a: Xinglong GWAC-F60A optical observation
- EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
- Fermi GRB 251125A: Global MASTER-Net observations report
- EP251124a: NOT r- and z-band optical upper limits
- EP251124a: Global MASTER-Net observations report
- GRB 251124A: Fermi GBM Localization by automated pipeline
- LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
- EP251124a: Optical upper limit with Kinder observations
- EP251118A: 6 GHz VLA Detection
- Fermi GRB 251124a: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
- LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
- EP251124a: GROWTH-India Telescope optical upper limits
- GRB 251116C: Swift-XRT confirmation of fading
- GRB 251122A/EP251122a: FTW optical and NIR observations
- GRB 251122A/EP251122A: 1.3m DFOT optical detection
- GRB 251122A / EP251122a: Xinglong 2.16m optical observation
- EP251118A: 3.6m DOT optical afterglow detection
- GRB 251122A / EP251122a: EP-FXT counterpart detection
- EP251122a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 251122A / EP251122a: WFST optical observations
- GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
- GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
- GRB 251122A / EP251122a: LCO optical upper limits
- EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
- EP251122a: Global MASTER-Net observations report
- GRB 251122A/EP251122a: SVOM/C-GFT upper limit
- GRB 251122A / EP251122a: SVOM detection of a long burst
- EP251118a: Continued Optical Detection with Kinder observations
- LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
- LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates
- GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
- GRB 251121A: Glowbug gamma-ray detection of a likely short burst
- EP251118a: Xinglong-2.16m optical observation
- GRB 251115A: Fermi GBM Observation
- EP251118A: 1.3m DFOT optical afterglow detection
- GRB 251118A: Swift/UVOT Detection
- EP251118a / GRB 251118C: SAO RAS optical observations
- GRB 251118A: Glowbug gamma-ray detection
- GRB 251118A: Fermi GBM Observation
- GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
- EP251118a: Optical detection with Kinder observations
- GRB 251118A: GECAM-B detection
- LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
- EP251118a / GRB 251118C: SVOM/VT optical observation
- GRB 251118A: NuSTAR detection of bright prompt emission
- EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
- GRB 251116C: NOT optical observations
- GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
- GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
- EP251118A / GRB 251118C : MASTER optical counterpart observations
- GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
- Konus-Wind detection of GRB 251118C (EP251118a)
- EP251118a: FTW optical and NIR observations
- GRB 251117A: Insight-HXMT/HE detection
- GRB 251119A: SVOM trigger sb25111901 is not a GRB
- EP251118a: VLT near-infrared observation
- GRB 251116D: SVOM/GRM observation of a long GRB
- EP251118a: GOTO optical afterglow detection
- EP251118a: NOT spectroscopic redshift of z = 1.216
- EP251118a: Global MASTER-Net observations report
- EP251118a: preliminary result of EP-FXT follow-up observation
- GRB 251118A: Fermi-LAT detection
- EP251118a: NOT candidate optical counterpart
- GRB 251118A: Swift ToO observations
- EP251118a: Einstein Probe detected of a fast X-ray transient
- Fermi GRB 251118B: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
- GRB 251117A: FTW Observations of Swift candidate X-ray sources
- GRB 251116C: SVOM/ECLAIRs refined analysis
- GRB 251116B: SVOM/ECLAIRs refined analysis
- GRB 251117A: AstroSat CZTI detection
- GRB 251114B: Insight-HXMT/HE detection
- GRB 251114B: GECAM-B detection of a short burst
- GRB 251117A: Fermi GBM observation
- GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
- LIGO/Virgo/KAGRA S251117dq: Updated Sky localization
- GRB 251116D: Insight-HXMT/HE detection
- GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
- GRB 251117A: SVOM/GRM observation of a short burst
- GRB 251117A: Tiled Swift observations
- GRB 251117A: Fermi-LAT detection
- LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
- GRB 251116C: Swift/BAT arcminute localization of a burst
- LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
- LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman
- GRB 251116B: SVOM/VT optical upper limit
- LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
- LIGO/Virgo/KAGRA S251116en: Updated Sky localization
- GRB 251116D: Glowbug gamma-ray detection
- EP251023a: Assy AZT-20 optical observations
- EP251023a: UAFO and AbAO optical observations
- LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
- The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
- GRB 251116C: SVOM/VT optical upper limit
- GRB 251025B: further Mondy optical observations