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').
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"- Swift Trigger 664610: is unlikely a GRB
- GRB 151118A: MITSuME Akeno optical upper limits
- GRB 151120A: Swift-XRT afterglow detection
- GRB 151120A: Fermi GBM observation
- GRB 151118A: AAO optical upper limit
- LIGO/Virgo G194575: Updated significance from offline GW analysis
- GRB 151120A: Swift ToO observations
- GRB 151120A: GROND optical/NIR afterglow
- GRB 151120A: A long GRB detected by INTEGRAL
- GRB 151118A, Swift-BAT refined analysis
- LIGO/Virgo G194575: Fermi GBM Observations
- 610 MHz detection of GRB 151027A with the GMRT
- GRB 151118A: Early optical limit from pt5m, La Palma
- GRB 151118A: ISON-NM early optical limit
- GRB 151118A: Swift-XRT refined Analysis
- GRB 151027A: SAO RAS and Mt. Terskol observations
- GRB 151118A: Swift/UVOT Upper Limits
- GRB 151118A: Enhanced Swift-XRT position
- GRB GRB 151118A: MASTER-NET optical observations
- GRB 151118A: Optical observations from OSN
- GRB 151118A: Swift detection of a burst
- Swift-BAT resumption of normal operations
- GRB151027A; Optical observations
- GMRT radio detection of GRB 151027A
- GRB 151114A: GROND Detection of the Optical/NIR Afterglow Candidate
- GRB 151114A: Swift-XRT refined Analysis
- GRB 151107B: CALET Gamma-Ray Burst Monitor detection
- GRB 151114A: Swift-BAT refined analysis
- GRB 151112A: GROND photometric redshift and i'-band prediction
- GRB 151114A: Swift/UVOT Detection
- GRB 151114A: LCOGT-FTS afterglow observations
- GRB 151114A: Enhanced Swift-XRT position
- GRB 151114A: Swift detection of a burst with an optical counterpart
- GRB 151111A: GROND confirmation of the afterglow and photometric redshift estimate
- GRB 151112A: Swift/UVOT Upper Limits
- GRB 151112A: MAXI/GSC detection
- GRB 151112A: GROND Detection of the Optical/NIR Afterglow Candidate
- GRB 151112A: Swift-XRT refined Analysis
- GRB 151112A: Swift-BAT refined analysis
- GRB 151112A: Enhanced Swift-XRT position
- GRB 151112A: MASTER-NET optical limit
- GRB 151112A: initial UVOT observations
- GRB 151112A: Swift-XRT observations
- GRB 151112A: Swift detection of a burst
- GRB 151111A: Swift/UVOT upper limits
- Swift-BAT trigger 663164 is not a burst.
- GRB 151111A: GROND marginal detection of a afterglow candidate
- LIGO/Virgo G194575: VLA follow-up
- GRB 151111A: Swift-XRT refined Analysis
- GRB 151111A: Fermi GBM observation
- GRB 151111A: LCOGT-FTS afterglow observations
- GRB 151111A: Swift-BAT refined analysis
- GRB 151111A: Enhanced Swift-XRT position
- GRB 151111A: Swift detection of a burst
- IPN triangulation of GRB151107B
- GRB 151107B: MASTER-NET OT detection inside the FERMI error box
- GRB 151027A: continued Mondy optical observations
- GRB 151107B: Mini-MegaTORTORA limits on simultaneous optical emission
- LIGO/Virgo G194575: Liverpool Telescope observations of iPTF-15dld and iPTF-15dni
- LIGO/Virgo G194575: La Silla QUEST, Pan-STARRS and PESSTO observations of iPTF15dld
- GRB 151107A: Further investigation of the source nature
- GRB 151107B
- LIGO/Virgo G194575: Swift observations if iPTF15dld
- GRB 151107A, Swift-BAT refined analysis
- GRB 151027A: Hankasalmi optical observations
- LIGO/Virgo G194575: INAF-TNG/Asiago Telescope follow-up of iPTF15dld
- GRB 151107A: MASTER-NET optical observations
- GRB 151107A: Swift detection of a possible burst
- LIGO/Virgo G194575: INAF-Asiago Telescope further analysis of iPTF candidates
- Swift-BAT triggers are disabled
- LIGO/Virgo G194575: INAF-Asiago Telescope follow-up of iPTF candidates
- LIGO/Virgo G194575: VLA follow-up
- GRB 151027A: Mondy optical observations
- GRB 151027A: Mt. Terskol observatory optical observation
- LIGO/Virgo G194575: MAXI/GSC further analysis
- GRB 150910A: CrAO optical observations
- GRB 151027A: the missing GeV component
- GRB 151029A: FRAM optical afterglow detection
- LIGO/Virgo G194575: LT Spectroscopy of iPTF-15dmk
- GRB 151027A: Correction to GCN 18519
- GRB 151031A: MITSuME Akeno optical upper limits
- GRB 151031A: GROND observation
- LIGO/Virgo G194575: LT Spectroscopy of iPTF candidates
- GRB 151027B: ATCA radio detection
- GRB 151031A
- GRB 151031A: Swift/UVOT Detection
- GRB 151030A: Fermi GBM observation
- GRB 151031A: Swift-XRT refined Analysis
- GRB 151027B: RATIR Late-Time Upper Limits
- GRB 151031A: Swift-BAT refined analysis
- GRB 151031A: Enhanced Swift-XRT position
- GRB 151031A: VLT/X-shooter optical counterpart and redshift
- GRB 151027A: optical follow-up observations
- GRB 151031A: Swift detection of a burst
- GRB 151027A: Continued P60 Monitoring
- LIGO/Virgo G194575: INAF-TNG follow-up of iPTF15dkm and iPTF15dlj
- Correction to the Trigger Time for Swift GRB 151029A
- GRB 151029A: MITSuME Ishigakijima upper limits
- GRB 151027A: Optical counterpart detection
- GRB 151029A: Swift-XRT refined Analysis