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"
4571 results found.
- GRB 240513A: Fermi GBM observation
- GRB 240513A: Swift-XRT observations
- LAT GRB240513.31: Global MASTER-Net observations report
- Fermi trigger No 737277727: Global MASTER-Net observations report
- Fermi trigger No 737247400: Global MASTER-Net observations report
- Fermi trigger No 737196587: Global MASTER-Net observations report
- Fermi trigger No 737168073: Global MASTER-Net observations report
- GRB 240511A: Swift-XRT refined Analysis
- Fermi trigger No 737173236: Global MASTER-Net observations report
- Fermi trigger No 737152719: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
- Fermi trigger No 736967879: Global MASTER-Net observations report
- Fermi trigger No 736564880: Global MASTER-Net observations report
- IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
- GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
- IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
- GRB 240503A: AstroSat CZTI detection
- Fermi GRB 240501A: Global MASTER-Net observations report
- Fermi trigger No 736197684: Global MASTER-Net observations report
- GRB 240426A: VZLUSAT-2 detection
- GRB 240407A: VZLUSAT-2 detection
- Fermi-LAT gamma-ray observations of IceCube-240424A
- LIGO/Virgo/KAGRA S240422ed: A transient discovered from Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
- LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
- GRB 240426A: AstroSat CZTI detection
- LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
- LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
- LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
- LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
- IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
- S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
- LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
- S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
- LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
- LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
- LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
- LIGO/Virgo/KAGRA S240422ed: Additional DECam GW-MMADS Candidates from the first two nights of observations
- Fermi trigger No 735697285: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
- LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
- LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
- IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
- LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn
- LIGO/Virgo/KAGRA S240422ed: ATCA follow-up of candidate counterparts
- LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
- LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
- LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
- LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
- LIGO/Virgo/KAGRA S240422ed: DECam GW-MMADS Candidates
- IceCube Alert 240424.08: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS
- LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
- LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
- LIGO/Virgo/KAGRA S240422ed: Magellan Observations
- Fermi trigger No 735470374: Global MASTER-Net observations report
- Fermi GRB 240422A: Global MASTER-Net observations report
- GRB 240422A: Fermi GBM Final Real-time Localization
- GRB 240421B: Swift-XRT refined Analysis
- EP240420a: Xinglong decaying optical counterpart
- Fermi trigger No 735280430: Global MASTER-Net observations report
- IceCube Alert 240419.98: Global MASTER-Net observations report
- GRB 240419B: Swift-XRT refined Analysis
- Swift GRB 240419A: Global MASTER-Net observations report
- GRB 240419A: Swift-XRT refined Analysis
- GRB 240418A: Swift-XRT refined Analysis
- GRB 240418A: Swift detection of a burst
- LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
- EP240416a: BOOTES-2/TELMA Optical Upper Limit
- EP240413a: BOOTES-2/TELMA Optical Upper Limit
- EP 240414a: BOOTES-4/MET Optical Upper Limits
- Fermi GRB 240415A: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
- Swift Trigger 1220736: detection of 4U 1543-62.
- Fermi GRB 240407A: Global MASTER-Net observations report
- LXT 240402A: MASTER optical observations with AGN in error-box
- Fermi GRB 240402A: Global MASTER-Net observations report
- X-ray transient EP20240331a: MeerLICHT optical upper limits
- GRB 240324A: AstroSat CZTI detection of a short burst
- Fermi GRB 240328B: Global MASTER-Net observations report
- Fermi GRB 240328A: Global MASTER-Net observations report
- X-ray transient EP240315a: continued ATCA monitoring
- Fermi trigger No 733092476: Global MASTER-Net observations report
- Fermi trigger No 732937833: Global MASTER-Net observations report
- Fermi GRB 240320A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
- GRB 240317B: Swift/BAT-GUANO Angular Error Correction
- X-ray transient EP240315a: Montarrenti Observatory optical upper limit
- Fermi GRB 240317B: Global MASTER-Net observations report
- Fermi GRB 240317A: Global MASTER-Net observations report
- GRB 240317B: Fermi GBM Final Real-time Localization
- Fermi trigger No 732299243: Global MASTER-Net observations report
- GRB 240309A: MAXI/GSC detection
- GRB 231215A: further radio observations with the VLA
- Fermi GRB 240306A: Global MASTER-Net observations report
- Fermi GRB 240305A: Global MASTER-Net observations report
- Improved IPN triangulation of GRB 240227A (short)
- Fermi trigger No 731161136: Global MASTER-Net observations report
- Fermi GRB 240229A: Global MASTER-Net observations report
- GRB 240225B : MITSuME Akeno optical afterglow candidate detection
- Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up