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"
24612 results found.
- GRB 241030B: TESS detection of optical counterpart
- 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: Upper limits from EP-WXT observations
- Integral GRB241109.89: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification
- EP241107a: AbAO optical upper limit
- LIGO/Virgo/KAGRA S241109bn: Upper limits from Fermi-GBM Observations
- GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
- LIGO/Virgo/KAGRA S241109p: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
- EP241109a: confirmation of a stellar flare by BOOTES-7
- GRB 241108A: Swift-XRT observations
- LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
- EP241107a: KAIT optical observations
- GRB 241030A: TESS observations
- GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
- EP241107a: Kinder optical follow-up observations
- GRB 241025A: radio detection with the VLA
- EP241107a: AKO Optical Afterglow Follow-Up Observations
- EP241107a: GSP detects optical counterpart
- GRB 241105A: SVOM/GRM observation
- EP241107a: OHP/T193 photometric and spectroscopic observations
- GRB 241105a: PRIME near-infrared upper limits
- GRB 241105A: ePESSTO+ NTT optical afterglow detection
- EP241107a: GIT optical observations
- EP241107a: SVOM/C-GFT optical observations
- EP241107a: AKO Optical Afterglow Detection
- GRB 241025A: LBT optical observations
- GRB 241105A: VLT/FORS2 optical afterglow rapid fading
- GRB 241105A: Swift/UVOT Detection
- GRB 241105A: Fermi GBM Observation of a Short Burst with Extended Emission
- 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 241105A: Swift-XRT afterglow detection
- GRB 241105A: VLT/FORS2 spectroscopic redshift z = 2.681
- GRB 241104A: Swift-XRT observations
- GRB 240511A: LCO upper limits
- GRB 241104A: Fermi GBM Observation
- GRB 241105A: Swift/BAT-GUANO arcminute localization of a short burst
- GRB 241104A: SVOM/VT optical candidate
- GRB 241104A/EP241104a: Optical upper limits with Kinder observations
- GRB 241104A: COLIBRÍ Upper Limits on the Optical Counterpart
- EP241104a: EP detection of GRB 241104A X-ray emission
- GRB 241010A: host galaxy redshift z = 0.977
- EP241101a NUTTelA-TAO / BSTI Measurements 2024-11-02
- GRB 240821A: further radio observations with the VLA
- EP241103a: GIT optical upper limit
- EP241021a: OHP/T193 further optical observations
- LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
- LIGO/Virgo/KAGRA S241102cy: Updated Sky localization
- LIGO/Virgo/KAGRA S241102br: Updated Sky localization
- EP241103a: Swift XRT detection and improved X-ray position
- EP241021a: continued SOAR observations
- EP241101a: Optical upper limits with Kinder observations
- EP241101a: OHP/T193 optical observations
- LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
- LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
- GRB 241030A: Swift-UVOT observations of the optical prompt flare
- EP241103a: GSP optical upper limit
- EP241103A: LCO optical observations
- EP241103a: an X-ray transient detected by Einstein Probe
- 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
- Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
- GRB241030A: OHP/T193 optical observations
- GRB 241101A: FRAM-ORM optical limit
- LIGO/Virgo/KAGRA S241101ee: Identification of a GW compact binary merger candidate
- GRB 241030A/EP241030a: TNOT observations of the optical counterpart
- EP241021a: Upper limit from Konus-Wind observations
- GRB 241101A: Swift-BAT refined analysis
- GRB 241030A: further SAO RAS optical observations
- GRB 241030A: Optical Observations via Virtual Telescope Project
- EP241021a: Liverpool Telescope optical follow-up observations
- GRB 241030B: Swift-XRT refined Analysis
- GRB 241026A: SAO RAS optical observations
- GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
- GRB 241101A: Swift detection of a burst
- GRB 241030B: NUTTelA-TAO / BSTI Optical Limits
- EP241021a: OHP/T193 optical observations
- GRB 241030A: Palomar 1-m telescope COSMOS optical observations
- GRB 241030B: Montarrenti Observatory optical upper limit
- EP241026b: Liverpool Telescope optical follow-up
- GRB 241030A: SAO RAS optical observations
- GRB 241030A: Fermi GBM Observation
- EP241021a: AMI-LA radio detection
- GRB 241030B : GIT optical upper limits
- GRB 241030B: LCOGT Optical Upper Limits
- GRB 241030B: Swift-BAT refined analysis
- GRB 241030A: Swift-BAT refined analysis
- GRB 241029A: COLIBRI Detection of the Optical Counterpart
- GRB 241030B: Swift/UVOT Detection
- GRB 241029A: LCO optical detection
- GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
- GRB 241030B : MITSuME Akeno optical upper limits
- GRB 241030A: COLIBRI Continuing Detection of the Afterglow