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"31636 results found.
- GRB 070125: UVOT Observations of a Fading Optical Afterglow
- GRB 070125: Continued P60 Observations
- GRB 070125: Keck/LRIS Spectroscopy -- Evidence for a very low redshift
- GRB 070125: Lick 3m Spectroscopy
- GRB070125: Swift-XRT Refined Analysis
- GRB 070125: SARA detection in R
- GRB 070125: P60 Optical Afterglow Candidate
- RHESSI Spectrum of GRB070125
- Konus-Wind observation of short hard GRB 070124
- GRB 070110: optical break
- Swift-BAT trigger 257213 is a Galactic Center transient
- GRB 070110: Continued Detection and Request for Ground Followup
- GRB 070110: Ep,i - Eiso correlation
- GRB 070107: Suzaku WAM observation of the prompt emission
- GRB 070110: VLT R-band photometry
- GRB 070110 declared a "Burst of Interest" by Swift team
- Further Retractions of previous Swift-BAT triggers
- GRB 070110: VLT absorption redshift
- GRB 070110: UVOT Observations of a Candidate Afterglow
- GRB070110: Swift XRT Team refined analysis
- GRB 070110, Swift-BAT refined analysis
- GRB070107 Swift/UVOT Observations of a Fading Optical Afterglow
- GRB070107: Swift/XRT refined analysis
- GRB 070107: Possible UVOT Afterglow
- GRB 070107, Swift-BAT refined analysis
- GRB 070107: Swift/XRT position
- VLA observation of GRB 061222B
- VLA detection of GRB 061222A
- GRB070103: APO SPIcam i' and z' limits
- GRB 061201: Nearby Galaxy Cluster Abell 995 is at z=0.0865
- GRB070103: KPNO 4m+FLAMINGOS J limit
- GRB 070103: Swift/UVOT Upper limits
- GRB070103: Swift XRT refined analysis
- GRB 070103, Swift-BAT refined analysis
- GRB 070103: NOT observations
- Retractions of previous Swift-BAT triggers
- GRB061222a: optical observations
- Konus-Wind observation of GRB 061222A
- GRB 061210: Swift/XRT Astrometry Correction
- GRB 050826: MDM Redshift
- GRB 061222B: TAROT La Silla observatory early optical observations
- GRB 061218: TAROT La Silla observatory early optical observations
- GRB 061222A: MITSuME Akeno optical upper limits
- GRB 061222A: Confirmation of Gemini Afterglow Candidate
- GRB 061222B: MITSuME Akeno optical upper limits
- GRB 061222A: Gemini Afterglow Candidate
- GRB 061222B, Swift-BAT refined analysis
- GRB061222A Swift/UVOT: Upper Limits
- GRB 061222B: Swift/UVOT Upper limits
- GRB 061222B: Observation with the KANATA 1.5m telescope
- GRB061222B: Swift-XRT Refined Analysis
- GRB 061222A: Observation with the KANATA 1.5m telescope
- GRB 061222B: BOOTES-IR optical observations
- GRB 061222B: SARA upper limit
- GRB 061222A: Swift-XRT refined analysis
- GRB 061217: Magellan host galaxy redshift
- GRB 061222A, Swift-BAT refined analysis
- GRB 061222B: REM NIR/optical observations
- GRB 061222b, SMARTS optical/IR afterglow observations
- GRB 061222B: TAROT La Silla observatory afterglow observation
- GRB 061222b: Magellan redshift
- GRB 061222B: Swift detection of a burst
- GRB 061222A: Prompt ROTSE-III Optical Limits
- GRB 061201: Magellan redshift of nearby galaxy
- GRB 061217: Confirmation of host candidate
- GRB 061217: Object ib GCN 5948 is a star
- GRB 061217: Extended object in the revised XRT error circle
- GRB 061217, Candidate host galaxy
- GRB 061217 - Swift/XRT position correction
- GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
- GRB 061201: Correction to GCN 5944
- GRB 061201: Magellan Redshift of nearby Abell cluster
- GRB 061218: TAROT La Silla observatory optical observations
- GRB 061217: TAROT Calern observatory optical observations
- GRB 061218: TORTOREM optical upper limits
- GRB 061218, Swift-BAT refined analysis
- GRB061217: VLT NIR observations
- GRB 061218, SMARTS optical/IR observations
- GRB 061218: REM prompt observations
- GRB 061217, SMARTS optical observations
- GRB061217: Swift/UVOT refined analysis.
- GRB 061217: optical observations at Calar Alto
- GRB061217 - Swift/XRT refined analysis
- GRB 061217, Further Swift-BAT refined analysis of the short hard burst
- GRB 061217, Swift-BAT refined analysis
- GRB 061217: Magellan Observations
- GRB 061217: REM prompt observations
- GRB 061217: ROTSE-III Optical Limits
- GRB 061210: MDM Follow-up Observation
- GRB061210: Swift/UVOT observations
- Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
- GRB 061210: Optical sources near XRT positions
- GRB 061210: Swift XRT analysis - Possible counterparts
- GRB 061210 : Faulkes North Telescope optical limit
- GRB 061214(?): ROTSE-III Optical Limits
- GRB 061210: Suzaku WAM observation of the prompt emission
- Swift/BAT trigger #250033 is due to a known source during loss of
- GRB 061213: MASTER-VWF-Kislovodsk OT candidate retraction
- GRB 061210: Gemini/GMOS Observations
- GRB 061126: Radio Observations