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"22063 results found.
- GRB 240421B: Swift/UVOT Upper Limits
- Fermi GRB 240421A: Global MASTER-Net observations report
- EP240420a: TNT upper limit to its optical counterpart
- EP240420a: Xinglong decaying optical counterpart
- EP240420a: Nanshan optical counterpart observations
- EP240420a: NOT optical counterpart candidate and potential host
- Fermi trigger No 735280430: Global MASTER-Net observations report
- GRB240418A - Candidate afterglow from NIRES
- IceCube Alert 240419.98: Global MASTER-Net observations report
- GRB 240419B: Swift/UVOT Upper Limits
- GRB 240419A: Swift/UVOT Upper Limits
- GRB 240419B: optical afterglow from the NOT
- EP240414a: Near-IR observations with NIRES and WINTER
- Swift GRB 240419B: Global MASTER-Net observations report
- Swift GRB 240419A: Global MASTER-Net observations report
- GRB 240418A: Swift/UVOT Upper Limits
- GRB 240419A: REM NIR afterglow detection
- GRB 240411B: Swift/UVOT Detection
- GRB 240419A: VLT/UVES redshift of z = 5.178
- GRB 240419A: VLT optical afterglow detection
- Fermi trigger No 735089036: Global MASTER-Net observations report
- EP240416a: J-band observations with WINTER
- GRB 240418A: TSHAO Zeiss-1000 optical upper limit
- GRB 240418A: NOT optical upper limits
- GRB 240411A: GOTO early optical upper limits
- Swift GRB240418.85: Global MASTER-Net observations report
- EP240417a: EP-WXT detection of a fast X-ray transient
- Fermi GRB 240417A: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
- EP240414a: GSP detects optical candidate counterpart AT2024gsa
- LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
- EP240414a: Pan-STARRS detects re-brightening of the candidate counterpart AT2024gsa
- LIGO/Virgo/KAGRA S240413p: historical ATLAS and ZTF observations of the candidate AGN counterpart
- LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
- EP240416A: MASTER optical observations
- EP240416a: Kinder optical counterpart candidate
- EP240416a: EP-WXT detection of a fast X-ray transient
- GRB 240414A: AbAO optical upprer limit
- GRB 240415A: Swift/UVOT Detection
- GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
- GRB 240415A: Earliest optical followup with the Kinder observations
- GRB 240415B: Swift ToO observations
- GRB 240415B: Swift/BAT-GUANO Correction
- GRB 240415B: Swift/BAT-GUANO arcminute localization of a short burst
- GRB 240415A: OHP/T193 optical observations
- GRB 240415A: optical afterglow detection from the INAF Asiago Observatory
- GRB 240415A: SAO RAS optical observations
- Fermi GRB 240415A: Global MASTER-Net observations report
- GRB 240415A: Mondy optical transient detection
- GRB 240414A: Photometric observation from 2.2m CAHA
- GRB 240414A: Swift/UVOT Detection
- LXT 240402A/GRB 240402B: Swift follow-up observations
- GRB 240414A: Mondy optical observations
- X-ray transient EP 240414a - GTC spectroscopic observations
- GRB 240415A: Prompt Swift-XRT observations
- EP 240414a: NOT optical counterpart confirmation
- GRB240414A : J-band upper limits from WINTER
- GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
- GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
- LIGO/Virgo/KAGRA S240413p: No Counterparts in DDOTI/OAN Optical Observations
- EP240413A: GOTO optical upper limits
- GRB 240414A: Skynet Optical Afterglow Observations
- Fermi trigger No 734754044: Global MASTER-Net observations report
- Swift GRB 240414A: Global MASTER-Net observations report
- EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
- Fermi-LAT gamma-ray observations of IceCube-240412A
- GRB 240414A : OHP/T193 redshift determination
- GRB 240414A : OHP/T193 optical counterpart detection
- LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S240413p: Zwicky Transient Facility observations
- EP240408a: GSP optical upper limit
- GRB 240411B: CrAO/ZTSh optical observations
- GRB 240411B: Kinder observations with Lulin observatory
- LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
- GRB 240411B: HiPERCAM/GTC observation
- IceCube Alert 240412.23: Global MASTER-Net observations report
- GRB 240411B: 1.3m DFOT Optical observations
- GRB 240411B: OHP/T193 optical observations
- GRB 240411B: LCO optical afterglow detection
- EP240408A: MASTER optical observations
- EP240408a: GROND detection of a candidate counterpart
- EP240408a: Swift follow-up observation
- X-ray transient EP240315a: second epoch e-MERLIN radio observations
- EP240408a: EP-WXT detection of a fast X-ray transient
- IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
- Fermi GRB 240408A: Global MASTER-Net observations report
- Fermi GRB 240407A: Global MASTER-Net observations report
- Fermi-LAT gamma-ray observations of IceCube-240327B
- Fermi-LAT gamma-ray observations of IceCube-240327A
- Fermi GRB 240405B: Global MASTER-Net observations report
- LXT 240402A/GRB 240402B: GECAM-C refined analysis
- Swift satellite resumes pointed science observations
- X-ray transient LXT 240402A: WFST optical upper limits
- IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
- GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
- LXT 240402A: EP-FXT detection of the X-ray afterglow
- Fermi GRB 240404A: Global MASTER-Net observations report
- LXT 240402A: MASTER optical observations with AGN in error-box
- X-ray transient LXT 240402A: LEIA detection
- Fermi trigger No 733808041: Global MASTER-Net observations report