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.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
- 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
- GRB241104A: Fermi GBM Observation
- GRB 241104A: The SVOM/VT candidate in GCN circular 38086 is not an astrophysical source
- GRB 241105A: Swift ToO observations
- GRB 241105A: Swift/BAT-GUANO arcminute localization of a short burst
- GRB 241104A: Swift ToO observations
- GRB 241104A: NOT optical non-detection
- GRB 241105A: GOTO tentative optical counterpart candidate
- Fermi GRB 241105A: Global MASTER-Net observations report
- GRB 241104A: SVOM/VT optical candidate
- GRB 241105A: Fermi GBM Final Real-time Localization
- GRB 241104A/EP241104a: Optical upper limits with Kinder observations
- GRB 241104A: COLIBRÍ Upper Limits on the Optical Counterpart
- GRB 241104A: SVOM/GRM observation
- 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 241104A : Detection and localization by SVOM/ECLAIRs
- GRB 240821A: further radio observations with the VLA
- Fermi GRB 241104A: Global MASTER-Net observations report
- GRB 241104A: Fermi GBM Final Real-time Localization
- GRB 241030A: GRBAlpha detection
- EP241101a: EP-FXT observations update
- EP241103a: GIT optical upper limit
- EP241021a: OHP/T193 further optical observations
- LIGO/Virgo/KAGRA S241104a: Retraction of GW compact binary merger candidate
- Fermi trigger No 752365806: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
- LIGO/Virgo/KAGRA S241102cy: Updated Sky localization
- EP241103a: GOTO optical upper limit
- LIGO/Virgo/KAGRA S241102br: Updated Sky localization
- EP241101a: Possible detection of an optical counterpart with FTW
- 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
- EP241103a: Gemini optical limits
- EP241103a: EP observation update
- 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: Global MASTER-Net observations report
- EP241103a: an X-ray transient detected by Einstein Probe
- GRB 241030A: Rapid release of TESS data.
- EP241101a: Global MASTER-Net observations report
- GRB 241029A: GRBAlpha detection
- EP241101a: BOOTES-7 optical upper limit
- 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
- EP241030a: Futher EP-FXT observation of the X-ray Afterglow of GRB 241030A
- EP241101a: EP-WXT detection of a fast X-ray transient
- Swift GRB 241101A: Global MASTER-Net observations report
- 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
- EP241030a: EP/FXT observation of GRB 241030A X-ray Afterglow
- GRB 241101A: Swift detection of a burst
- GRB 241030B: NUTTelA-TAO / BSTI Optical Limits (duplicate submission of 38023)
- 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
- GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
- EP241026b: Liverpool Telescope optical follow-up
- Fermi trigger No 752083996: Global MASTER-Net observations report
- 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
- EP EP241030a: Global MASTER-Net observations report
- GRB 241029A: LCO optical detection
- Fermi trigger No 752006065: Global MASTER-Net observations report
- GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
- Swift GRB241030.77: Global MASTER-Net observations report
- GRB 241030B: SVOM/GRM observation
- GRB 241030B : MITSuME Akeno optical upper limits
- GRB 241030A: COLIBRI Continuing Detection of the Afterglow
- GRB 241030B: SVOM/VT optical afterglow observations