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 240821A: PRIME near-infrared observations
- GRB 240825A: VLA detection
- Fermi GRB 240828A: Global MASTER-Net observations report
- Fermi trigger No 746438824: Global MASTER-Net observations report
- SVOM GRB 240821A: optical afterglow discovery
- GRB 240828B : Detection of a possible very soft X-ray transient by SVOM/ECLAIRs
- GRB 240828A: Fermi GBM Final Real-time Localization
- GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
- GRB 240825A: GECAM detection
- GRB 240825A: ALMA detection
- GRB 240825A: SAO RAS optical observations
- GRB 240824A: GIT optical upper limit
- GRB 240819A: Swift afterglow confirmation
- GRB 240825A: TNG optical photometry and spectroscopy
- LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
- LIGO/Virgo/KAGRA S240825ar: Updated Sky localization
- GRB 240825A: NUTTelA-TAO / BSTI Optical Limits
- GRB 240825A: GMG Continued Optical Observation on the Second Night
- GRB 240824B: Ondrejov D50 optical limit
- GRB 240825A: KAIT optical observations
- GRB 240825A: PRIME near-infrared detection
- Konus-Wind detection of GRB 240825A (bright/long)
- GRB 240825A: Fermi GBM Observation
- GRB 240825A : MISTRAL/T193 OHP optical follow-up of the afterglow
- GRB 240825A: AKO Optical Follow-Up Observations
- GRB 240825A: AstroSat CZTI detection of the long bright burst
- SGR 1E 1841-045 / Kes 73: SVOM/GRM observation
- GRB 240825A: Swift/UVOT Detection
- GRB 240825A: REM detection of the optical/NIR afterglow
- GRB 240825A: Swift-XRT refined Analysis
- GRB 240825A: VLT/X-shooter redshift
- GRB 240825A: SVOM/C-GFT optical observations
- GRB 240825A: Montarrenti Observatory optical observations
- GRB 240825A: Enhanced Swift-XRT position
- GRB 240825A: MASTER optical counterpart observation
- GRB 240825A: Fermi-LAT detection
- GRB 240825A: LCO optical observations
- GRB 240824B: KAIT optical upper limit
- SGR 1E 1841-045 / Kes 73 (Trigger 1249878): Osservatorio Atronomico Nastro Verde optical upper limit
- GRB 240824B: Fermi GBM Observation
- Fermi GRB 240825A: Global MASTER-Net observations report
- SGR 1E 1841-045 / Kes 73 (Trigger 1249653) - Osservatorio Astronomico Nastro Verde upper limit
- GRB 240824B: NOT optical upper limit
- GRB 240825A: GMG Optical Observation
- Swift GRB 240825A: Global MASTER-Net observations report
- GRB 240825A: 1.6m Mephisto multi-band detection
- GRB 240825A: AKO Optical Afterglow Detection
- GRB 240825A: Skynet Optical Afterglow observations
- GRB 240825A: Nanshan/HMT optical afterglow observations
- GRB 240825A: Swift detection of a burst with a bright optical counterpart
- GRB 240825A: Fermi GBM Final Real-time Localization
- GRB 240824A: Swift-BAT refined analysis
- GRB 240824A: SVOM/C-GFT optical upper limit
- GRB 240824B: Swift-XRT afterglow detection
- GRB 240824A: Swift-XRT observations
- LIGO/Virgo/KAGRA S240825ar: Identification of a GW compact binary merger candidate
- GRB 240824B: Swift/BAT arcminute localization of a burst
- GRB 240824B: Swift ToO observations
- Fermi GRB 240824C: Global MASTER-Net observations report
- GRB 240824C: Fermi GBM Final Localization
- GRB 240824A: Swift/UVOT Upper Limits
- GRB 240821A: Swift/UVOT observations of the XRT sources.
- GRB 240824B: MAXI/GSC detection
- GRB 240824B: Fermi GBM Final Real-time Localization
- GRB 240824A: Retraction of GCN 37255
- GRB240824A: GRANDMA/TAROT-TCA Upper Limit
- SGR 1E 1841-045 / Kes 73: Leavitt Observatory optical upper limit
- GRB 240824A: KAIT optical upper limit
- GRB 240824A: Skynet Optical Afterglow Discovery
- GRB 240824A: Swift detection of a burst
- Swift GRB240824.04: Global MASTER-Net observations report
- SGR 1E 1841-045 / Kes 73: Montarrenti Observatory optical upper limits
- GRB 240821A: Colibri Optical Upper Limit
- EP240820a: PRIME J-band Observations
- GRB 240821A: Swift-XRT observations
- GRB 240822A: AstroSat CZTI detection of a short burst
- GRB 240821A: REM optical/NIR upper limits
- GRB 240821A: LCO optical observations
- GRB 240821A: JinShan optical upper limits
- GRB 240809A: Mondy and AbAO Optical Observations
- GRB 240821A: SVOM/VT follow-up and optical upper limit
- GRB 240821A: GMG Optical Upper Limit
- Fermi GRB 240821A: Global MASTER-Net observations report
- GECAM-B observation of a short burst from SGR 1E 1841-045 / Kes 73
- GRB 240821A: Fermi GBM Observation
- Fermi trigger No 745964969: Global MASTER-Net observations report
- Fermi trigger No 745925274: Global MASTER-Net observations report
- GRB 240821A: Swift ToO observations
- Fermi trigger No 746019401: Global MASTER-Net observations report
- Fermi-GBM Observations of the reactivation of SGR 1E 1841-045 / Kes 73
- Fermi trigger No 745935375: Global MASTER-Net observations report
- GRB240821A: EIRSAT-1 GMOD Detection
- GRB240821B: First GRB Detected by EIRSAT-1 GMOD
- GRB 240821A: EP-FXT follow-up observation and afterglow candidates
- Fermi GRB 240821B: Global MASTER-Net observations report
- EP240801a: Keck/LRIS spectroscopic redshift confirmation
- GRB 240821A: SVOM/GRM observation
- GRB 240821A: SVOM/GRM observation
- GRB 240821A: GRANDMA/LesMakes-T60 Upper Limit
- GRB 240821B: Fermi GBM Final Localization