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"8474 results found.
- LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
- LIGO/Virgo/KAGRA S241125n: Updated Sky localization
- LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
- LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
- LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
- LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
- LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241122a: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S241122a: Identification of a GW compact binary merger candidate
- GRB241120A: OHP/T193 optical observations
- GRB 241120A: Mondy and AbAO optical observations
- GRB 241112B: Mephisto further optical observations
- LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S241114y: Updated Sky localization
- Updates to IceCube realtime alert system for muon tracks
- IceCube-Cascade 241116A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S241116cq: Updated Sky localization
- LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
- GRB 241113B: Mephisto upper limits
- LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S241113p: Updated Sky localization
- EP241113a: No Detection in Fermi-GBM Observations
- GRB 241115A: Swift detection of a burst
- EP 241113a: LBT possible optical counterpart
- GRB 241113B: KAIT Optical Afterglow Candidate
- LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
- IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
- Konus-Wind detection of GRB 241107A (short/hard)
- LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
- GRB 241113B: Swift ToO observations
- IceCube-241113A - IceCube observation of a high-energy neutrino candidate track-like event
- LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
- Fermi-GBM Sub-Threshold Detection of GRB 241112B
- GRB 241112B: LCO optical detection of the SVOM/VT candidate
- GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
- GRB 241112B: Mephisto optical upper limits
- GRB 241112B: Swift ToO observations
- LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241110br: Updated Sky localization
- LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
- LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S241109bn: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S241109p: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
- GRB 241108A: Swift ToO observations
- GRB 241108A : a likely weak long GRB detected by SVOM/ECLAIRs
- EP241107a: Kinder optical follow-up observations
- GRB 241025A: radio detection with the VLA
- EP241101a: CrAO ZTSH optical observations
- LIGO/Virgo/KAGRA S241106ba: 1 counterpart neutrino candidate event from an IceCube neutrino search
- LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
- GRB 241104A: The SVOM/VT candidate in GCN circular 38086 is not an astrophysical source
- GRB 241105A: Swift ToO observations
- GRB 241104A: Swift ToO observations
- GRB 241104A: NOT optical non-detection
- GRB 241105A: GOTO tentative optical counterpart candidate
- GRB 241104A: SVOM/VT optical candidate
- GRB 240821A: further radio observations with the VLA
- EP241101a: EP-FXT observations update
- LIGO/Virgo/KAGRA S241104a: Retraction of GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241102cy: Updated Sky localization
- LIGO/Virgo/KAGRA S241102br: Updated Sky localization
- EP241103a: Swift XRT detection and improved X-ray position
- EP241101a: Optical upper limits with Kinder observations
- EP241101a: OHP/T193 optical observations
- EP241103a: Gemini optical limits
- LIGO/Virgo/KAGRA S241101ee: Updated Sky localization
- S241102cy: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241102br: NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241101ee: Identification of a GW compact binary merger candidate
- GRB 241030B: Montarrenti Observatory optical upper limit
- GRB241030B: GRANDMA/TAROT Upper Limit
- GRB 241030B: Swift detection of a burst
- GRB 240912A: radio detection with the VLA
- GRB 241030A: AKO Optical Afterglow Detection
- GRB 241030A: Swift detection of a burst with a bright optical counterpart
- GRB 241029A: TRT optical afterglow candidate detection
- GRB 241029A: Swift ToO observations
- GRB 241026A: Swift detection of a burst
- LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
- EP 241021A: Swift ToO observations
- GRB 241025A: Swift detection of a burst with an optical counterpart
- GRB 241001A: ATCA radio observations
- EP241021a: No Detection in Fermi-GBM Observation
- EP241021a: Optical counterpart observations with the Liverpool Telescope
- EP241021a: GSP detects optical candidate counterpart
- EP241021a: Optical upper limits with Kinder observations
- IceCube-Cascade 241019A: Upper limits from a search for additional neutrino events in IceCube
- GRB 241018A/sb24101802: Mephisto optical upper limit
- GRB 241018A: REM optical/NIR upper limits
- GRB 241018A: NOT optical observations
- GRB 241018A: SVOM/VT follow-up and optical candidate