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.
Lucene Examples (click to copy):
subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
32086 results found.
- Fermi Gamma-ray Burst Monitor trigger 766474855/250416237 is not a GRB
- GRB 250413A: AstroSat CZTI detection
- EP250304a: ATCA radio observations
- GRB 250412A: AstroSat CZTI detection
- GRB 250411A: DDOTI Optical Observations
- Fermi GRB 250411A: Global MASTER-Net observations report
- GRB 250411A: Fermi GBM Final Real-time Localization
- GRB 250407A: Continued KAIT/Nickel optical observations
- GRB 250314A: e-MERLIN observations
- GRB 250407A: Mondy and AbAO Optical Observations
- GRB 250320B: cubesat Avion detection
- IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
- IPN triangulation of GRB 250407A
- GRB 250407A: LCO detection of a fading optical counterpart
- EP250407a: Swift-XRT observations
- Konus-Wind detection of GRB 250407A
- GRB 250407A: SVOM/GRM observation of a bright long burst
- GRB 250407A: EP-WXT afterglow detection
- GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
- GRB 250407A: KAIT Optical Afterglow Candidate
- GRB 250407A: Fermi GBM Detection
- GRB 250407A: Swift-XRT afterglow detection
- Fermi GRB 250407A: Global MASTER-Net observations report
- GRB 250407A: Swift ToO observations
- GRB 250407A: SRG/ART-XC afterglow detection
- LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
- Konus-Wind detection of GRB 250406B (short/hard)
- IPN triangulation of GRB 250406B (short/hard)
- GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
- GRB 250407A: Fermi GBM Final Real-time Localization
- GRB 250406A: AstroSat CZTI detection
- Fermi GRB 250406A: Global MASTER-Net observations report
- GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
- GRB 250406A: Fermi GBM Final Real-time Localization
- EP250404a / GRB 250404A: Montarrenti Observatory optical observations
- Fermi Gamma-ray Burst Monitor trigger 765619921/250406342 is not a GRB
- GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
- GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
- EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
- Konus-Wind detection of GRB 250404A / EP250404a
- GRB 250404A / EP250404a: Mondy optical observations
- GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
- GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
- GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
- GRB 250404A / EP250404a: NOT optical observations
- GRB 250331D: Swift-XRT afterglow detection
- GRB 250404B: AstroSat CZTI detection of a short burst
- GRB 250403A: AstroSat CZTI detection
- EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
- EP250404a: REM optical/NIR observations
- EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
- EP250404a: LCO optical counterpart detection
- Fermi GRB 250404A: Global MASTER-Net observations report
- GRB 250403A: Montarrenti Observatory optical detection
- GRB 250404A: Fermi GBM Detection
- GRB 250403A: KAIT optical observations
- GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
- EP250404a: Xinglong-2.16m spectroscopic redshift
- GRB 250403A: Fermi GBM observations
- GRB 250327B: VIRT Optical Upper Limit
- GRB 250331C Swift-BAT refined analysis
- GRB 250331B Swift-BAT refined analysis
- GRB 250330A Swift-BAT refined analysis
- EP250404a: Nanshan/HMT optical counterpart detection
- EP250404a: Einstein Probe detection of an X-ray transient
- GRB 250404A: Fermi GBM Final Real-time Localization
- GRB 250402A: Mondy optical observations
- GRB 250403A: Swift/UVOT Detection
- GRB 250402A: Swift/UVOT Upper Limits
- GRB 250403A: SVOM/VT optical observation
- GRB 250403A: REM NIR afterglow detection
- GRB 250403A: LCO optical counterpart detection
- GRB 250403A: JinShan optical observations
- GRB 250402A: EP-FXT afterglow detection
- GRB 250403A: Optical counterpart detection by LCO.
- GRB 250403A: Swift-XRT observations
- GRB 250322A: 10 GHz VLA radio upper limits
- Fermi GRB 250403A: Global MASTER-Net observations report
- GRB 250403A: GOTO optical counterpart follow-up observations
- GRB 250402A: NUTTelA-TAO Early Optical Limits
- GRB 250403A: GMG Optical Observation
- GRB 250403A: 1.6m Mephisto multi-band optical detection
- GRB 250402A: Fermi GBM Observation
- GRB 250403A: SVOM/C-GFT optical observations
- GRB 250403A: GOTO detection of the optical afterglow
- GRB 250402A: Swift-XRT observations
- GRB 250403A : SVOM detection of a burst
- GRB 250403A: Fermi GBM Final Real-time Localization
- GRB 250225B: VLT host galaxy redshift z = 0.950
- GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
- GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
- GRB 250402A: REM optical/NIR upper limits
- GRB 250402A: LCO optical counterpart detection
- GRB 250402A: refined SVOM/MXT data analysis
- GRB 250402B: AstroSat CZTI detection of a short burst
- GRB 250402A: SVOM/VT optical counterpart
- GRB 250402A: SVOM detection of a burst
- GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
- GRB 250314A: ALMA detection
- GRB 250329B: Swift/UVOT Upper Limit