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"- GRB 080123: Swift detection of a short burst
- GRB 080120: GROND confirmation of the optical afterglow
- XRF 080109 / SN 2008D: GMRT radio observation at 1280 MHz
- VLA radio upper limit on GRB 080120
- GRB 080120: Swift-XRT refined analysis
- UVOT detection of GRB080120
- GRB 080120: GROND detection
- GRB 080120 : Planned XMM-Newton observation
- GRB080120: Swift XRT position
- GRB 080120: a long GRB detected by INTEGRAL
- XRF 080109 / SN 2008D: 1.4 GHz WSRT Radio Observations
- Transient in NGC2770 / SN2008D: Metallicity of nearby HII regions
- Transient XRF 080109 / SN 2008D: Mount Abu NIR observations
- XRF 080109 / SN 2008D: WSRT Radio Detection
- Transient 080109/ SN 2008D, metallicity of the host galaxy
- Transient 080109/ SN 2008D, IR Spectrum
- XRF 080109 / SN 2008D: optical observations
- NGC 2770B has the same redshift as NGC 2770
- Swift UVOT Monitoring of the SN 2008D Brightening (Transient in NGC 2770)
- XRF 080109 / SN 2008D: spectroscopic evolution
- XRF 080109 / SN 2008D: UKIRT JHK imaging
- optical observations, XRT in NGC 2770
- XRF 080109/SN 2008D: PROMPT Optical Imaging
- Gemini-South observations of XRF 080109 / SN 2008D
- Swift observations of the X-ray transient in NGC 2770 (aka SN2008D)
- Discovery of Radio Emission from Transient in NGC 2770
- XRF 080109 in NGC2770: NIR observations at TNG
- XRB 080109/SN 2008D: Early decline in brightness and change in colors
- XRB 080109/SN 2008D:PAIRITEL NIR observations and t_0 from Swift
- XRF 080109 in NGC2770: Detectable Superluminal Motion
- Detailed Spectroscopic ID of SN 2008D (Transient in NGC 2770)
- XRF in NGC 2770: Search for X-ray periodicity
- Spectroscopic classification of SN 2008D (Transient in NGC 2770)
- Refined Swift-XRT analysis of the transient in NGC 2770
- Transient in NGC 2770: spectroscopic evidence for a SN
- Refined Swift UVOT Analysis of SN 2008D (Transient in NGC 2770)
- Opticall follow-ups for the X-ray transient in NGC 2770
- X-ray transient in NGC 2770: Optical observations with Astrotel-Caucasus
- Optical Spectroscopy of the Transient in NGC 2770
- Swift UVOT Observations of the X-ray transient in NGC 2770
- Early OT detection of XRF in NGC 2770 in Asiago frames
- Bright X-ray transient / possible XRF in NGC 2770: TNG R imaging
- Possible XRF in NGC 2770 - NOT observations of the optical counterpart
- Bright X-ray Transient (a XRF? ) in NGC 2770 - A SN optical counterpart?
- Bright X-ray Transient in NGC 2770 - A low-luminosity XRF?
- GRB 071227: Suzaku WAM observation of the prompt emission
- GRB 071227: optical afterglow
- Further Swift-BAT analysis of GRB 071227
- Konus-Wind observation of GRB 071227
- GRB 071227: Magellan redshift confirmation
- GRB 071227: Swift-XRT refined analysis
- GRB 071227: VLT probable redshift of the candidate host galaxy
- GRB 071227: Magellan observations
- GRB071227: Swift/UVOT refined analysis
- GRB 071227: REM NIR and Optical observations
- Swift-BAT refined analysis of short GRB 071227
- GRB 071227: Swift detection of a burst
- GRB071020: optical observations
- GRB 070429B: Possible UVOT Detection of an Optical Afterglow
- Swift-BAT trigger 298308 is not a GRB
- GRB 071208?: Swift detection of a possible burst
- IBAS Alert #4772 in not a GRB
- GRB 071125: Suzaku WAM observation of the prompt emission
- GRB 070429B: Probable host galaxy and redshift
- GRB 071129, Swift-BAT refined analysis
- GRB 071129: Swift detection of a burst
- Konus-Wind and Konus-A observations of GRB 071125
- IPN triangulation of very bright GRB 071125
- GRB 071112C: Optical/NIR observations
- Disregard the "GRB 071126" position
- GRB 071126: Enhanced Swift-XRT position
- VLA radio detection of GRB 071122
- GRB071122: Swift/UVOT Observations
- GRB071104: NIR Afterglow Candidate at TNG
- GRB 071122: MASTER optical observation
- GRB 071122, Swift-BAT refined analysis
- GRB 071122 Swift XRT position update sent in error.
- GRB 071122 Swift-XRT refined analysis
- GRB 071122: Corrected P60 Coordinates
- GRB071122: Gemini Absorption redshift
- GRB 071122: P60 Optical Afterglow Candidate
- GRB 071122: ROTSE-III Optical Limits
- GRB 071122: Swift detection of a burst
- GRB 071118: P60 Observations
- GRB071118 MITSuME OAO optical observation
- GRB 071118: Observations from OSN
- GRB 071117: VLT observations and probable redshift
- Swift/UVOT observations of GRB071118
- GRB 071117: Swift-XRT revised position
- Konus-Wind and Konus-A observations of GRB 071117
- Swift XRT follow-up observations of GRB071008
- Swift/UVOT upper limits for GRB 071117
- GRB071118: Swift XRT refined analysis
- GRB 071117: Gemini Optical Afterglow Discovery
- GRB 071118, Swift-BAT refined analysis
- GRB 071117: TAROT La Silla observatory optical observations
- GRB 071112B: Gemini Image Differencing
- GRB 071118: Swift detection of a burst
- GRB 071117: Gemini Observations
- GRB 071117: Las Campanas optical observations