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"7417 results found.
- LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
- EP240908a: Updates on the WXT detection result around the trigger time
- LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
- EP240908a: optical afterglow candidate
- GRB 240905B: GOTO optical upper limits
- LIGO/Virgo/KAGRA S240908dg: Updated Sky localization
- LIGO/Virgo/KAGRA S240908bs: Updated Sky localization
- LIGO/Virgo/KAGRA S240908dg: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240908bs: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240907cg: Updated Sky localization
- LIGO/Virgo/KAGRA S240907cg: Identification of a GW compact binary merger candidate
- GRB 240905E: GIT optical upper limit
- GRB 240905B: Swift ToO observations
- GRB 240905E: J-band observations with WINTER
- GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
- GRB 240905E: AKO Optical Upper Limit
- GRB 240905E: Swift detection of a burst
- LIGO/Virgo/KAGRA S240825ar: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240807h: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240902bq: Updated Sky localization
- LIGO/Virgo/KAGRA S240902bq: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240830gn: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S240830gn: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S240830gn: Identification of a GW compact binary merger candidate
- GRB 240828B: SVOM/C-GFT optical upper limit
- GRB 240828B: KAIT optical upper limit
- GRB 240828A: KAIT Optical Afterglow Candidate
- GRB 240828A: Tiled Swift observations
- GRB 240825A: Upper limits from a neutrino search with IceCube
- GRB 240828B: Swift ToO observations
- GRB 240821A: PRIME near-infrared observations
- SVOM GRB 240821A: optical afterglow discovery
- GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
- LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
- LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
- GRB 240824B: KAIT optical upper limit
- GRB 240824B: NOT optical upper limit
- GRB 240825A: Skynet Optical Afterglow observations
- GRB 240825A: Swift detection of a burst with a bright optical counterpart
- GRB 240824A: SVOM/C-GFT optical upper limit
- LIGO/Virgo/KAGRA S240825ar: Identification of a GW compact binary merger candidate
- GRB 240824B: Swift ToO observations
- GRB240824A: GRANDMA/TAROT-TCA Upper Limit
- GRB 240824A: Swift detection of a burst
- SGR 1E 1841-045 / Kes 73: Montarrenti Observatory optical upper limits
- EP240820a: PRIME J-band Observations
- GRB 240821A: GMG Optical Upper Limit
- GRB 240821A: Swift ToO observations
- GRB 240821A: EP-FXT follow-up observation and afterglow candidates
- GRB 240819A: JinShan optical upper limits on one Swift/XRT source
- GRB 240819A: KAIT optical upper limit
- EP240816a: PRIME upper limits
- GRB 240819A: Swift ToO observations
- EP240816b: KAIT optical upper limit
- LIGO/Virgo/KAGRA S240813d: Updated Sky localization
- LIGO/Virgo/KAGRA S240813d: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240813c: Updated Sky localization
- LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
- GRB 240811A: Swift detection of a burst
- LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
- GRB 240809A: Swift detection of a burst with a bright optical counterpart
- IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
- S240807h: Identification of a GW compact binary merger candidate
- The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
- GRB 240626B: VZLUSAT-2 detection
- EP240806a: GSP optical counterpart detection
- GRB 240805B: Optical detection with 1.6m Mephisto
- GRB 240805B: BTA optical afterglow candidate
- EP240804a: GSP detects optical candidate counterpart
- GRB 240805B: Swift detection of a burst
- EP240804a: NOT optical counterpart detection
- EP240802a: Montarrenti Observatory optical upper limit
- EP240801a: GSP follow-up observations of the candidate counterpart
- EP240801a: Kinder follow-up observations of the candidate counterpart
- EP240708a: Kinder follow-up observations of the candidate counterpart (duplicate submission of GCN 37002)
- GRB 240730A: KAIT Optical Upper Limit
- GRB 240730A: Swift detection of a burst
- LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
- GRB 240727A: observations of optical counterpart.
- GRB 240727B: Swift ToO observations
- GRB 240727A: KAIT Optical Afterglow Candidate
- IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
- Swift Trigger 1244778 is not a GRB
- LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
- IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
- LIGO/Virgo/KAGRA S240716b: Updated Sky localization
- GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
- LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
- GRB 240715A: Swift ToO observations
- GRB 240713A: optical upper limits from the INAF Asiago Observatory
- The EP-WXT source triggered on July 14th is likely a flaring star
- GRB 240713A: Tiled Swift observations
- GRB 240712A: Swift detection of a burst
- LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S240627by: Updated Sky localization and EM Bright Classification
- EP240708a: KAIT optical upper limit
- LIGO/Virgo/KAGRA S240705at: Updated Sky localization
- LIGO/Virgo/KAGRA S240705at: Identification of a GW compact binary merger candidate