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 070125: Continued P60 Observations
- GRB 070125: pseudo-z~1.5 from spectral parameters of the prompt emission
- 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
- GRB 070126?: Swift detection of a possible burst
- GRB070125 redshift request
- RHESSI Spectrum of GRB070125
- IPN-BAT localization of GRB070125 (very long duration, intense)
- Konus-Wind observation of short hard GRB 070124
- IPN localization of GRB070124 (short duration, hard spectrum)
- GRB 070110: optical break
- Swift-BAT trigger 257213 is a Galactic Center transient
- GRB 070110: Continued Detection and Request for Ground Followup
- GRB 050904: Second Epoch of HST/NICMOS Observations
- 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
- Swift-BAT Trigger 255685 is not a GRB
- Trigger 255685: Swift detection of a possible burst
- 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
- GRB 070110: Swift detection of a burst with a possible optical afterglow
- IBAS Alert n. 4047: Not a GRB
- GRB070107: Swift/XRT refined analysis
- GRB 070107: Possible UVOT Afterglow
- GRB 070107, Swift-BAT refined analysis
- GRB 070107: Swift/XRT position
- GRB 070107: Swift detection of a burst
- 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
- GRB 070103: TAROT Calern observatory optical observations
- GRB 070103: Swift detection of a burst
- Retractions of previous Swift-BAT triggers
- GRB061222a: optical observations
- erratum : SDSS Pre-burst Observations of GRB061126
- 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: Xinglong Optical Limit
- 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: Refined redshift
- GRB 061222b, SMARTS optical/IR afterglow observations
- GRB 061222B: TAROT La Silla observatory afterglow observation
- GRB 061222B: TAROT La Silla observatory optical observations
- GRB 061222b: Magellan redshift
- GRB 061222B: Swift detection of a burst
- GRB 061222b: optical afterglow
- GRB 061222A: Prompt ROTSE-III Optical Limits
- GRB 061222: Swift detection of a burst
- GRB 061217: Astrometry-Corrected XRT Position
- 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
- Swift triggers (#251863) on a possible burst
- GRB 061217, SMARTS optical observations