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.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"23572 results found.
- SVOM GRB260603.23: Global MASTER-Net observations report
- Fermi GRB 260602B: Global MASTER-Net observations report
- Fermi GRB 260602B: Global MASTER-Net observations report
- EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
- GRB 260601B/EP260601a: J-band upper limit with WINTER
- EP260530a/AT 2026nwl: COLIBRÍ optical follow up
- EP260530a/AT 2026nwl: KAIT optical observations
- GRB 260601B: CALET Gamma-Ray Burst Monitor detection
- EP260602a: Optical upper limits with Kinder observations
- EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
- GRB 260601A: Glowbug gamma-ray detection of a short burst
- GRB 260531B: Glowbug gamma-ray detection
- EP260530a/AT 2026nwl: COLIBRÍ optical observations
- GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
- Fermi GRB 260601A: Global MASTER-Net observations report
- GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
- Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
- Fermi trigger No 801900520: Global MASTER-Net observations report
- GRB 260531A: MAXI/GSC detection
- AT 2026nuz: COLIBRÍ optical observations
- IPN triangulation of GRB 260527A / EP260527a
- GRB 260527A / EP260527a: VLA radio detection
- EP260527a/GRB 260527A: optical upper limit with Kinder observations
- GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
- GRB 260529A: GOTO tentative optical afterglow candidate
- GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
- Fermi GRB 260529A: Global MASTER-Net observations report
- EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
- EP260527a / GRB 260527A: NOT optical observations
- EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
- GRB 260527A: CALET Gamma-Ray Burst Monitor detection
- GRB 260526A: GECAM-B observation
- Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
- EP260526a: EP-FXT follow-up observation
- EP260527a: COLIBRÍ optical detection
- The EP-WXT trigger 01709266172 is likely a flaring star
- The EP-WXT trigger 01709266147 is likely a flaring star
- Fermi trigger No 801580882: Global MASTER-Net observations report
- GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
- GRB 260525A: AstroSat CZTI detection
- EP260526.405: COLIBRÍ optical upper limits
- GRB 260523B: AstroSat CZTI detection
- EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
- GRB 260522A: GOTO optical upper limit
- GRB 260519C: SVOM/GRM observation
- GRB 260511A: iTelescope T-75 optical detection
- GRB 260411B: TERI Gamma-ray detection
- GRB 260407A: TERI Gamma-ray detection
- GRB 260307A: TERI Gamma-ray detection
- GRB 260225D: TERI Gamma-ray detection
- GRB 251118A: TERI Gamma-ray detection
- GRB 251113A: TERI Gamma-ray detection
- GRB 260428A: TERI Gamma-ray detection
- Konus-Wind detection of GRB 260519C
- GRB 260509A: SVOM/ECLAIRs refined analysis
- Konus-Wind detection of GRB 260518A
- GRB 260518A: AstroSat CZTI detection of a long burst
- GRB 260516D: SVOM/ECLAIRs refined analysis
- GRB 260515A: SVOM/ECLAIRs refined analysis
- GRB 260421B: radio detection with the VLA
- GRB 260516D: GOTO optical counterpart detection
- GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
- GRB 260516D: SVOM/VT optical bright candidate
- GRB 260515A: CrAO ZTSh BVRI optical observations
- GRB 260516D: SVOM possible detection of a burst
- Konus-Wind detection of GRB 260515A
- GRB 260515A: LCO optical counterpart detection
- GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
- EP260514a: TRT optical counterpart candidate
- GRB 260515A: SVOM/VT optical observations
- GRB 260515A: OHP/T193 optical observations
- EP260514a: COLIBRÍ optical upper limits
- GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
- GRB 260515A: SVOM detection of a burst
- GRB 260510C: Glowbug gamma-ray detection
- GRB 260511B: NOT optical observations
- Konus-Wind detection of GRB 260512A
- GRB 260510C: CALET Gamma-Ray Burst Monitor detection
- EP260512a: LCO optical upper limits
- IPN triangulation of GRB 260512A
- GRB 260511B: Mephisto multi-band optical followup
- GRB 260512A: AstroSat CZTI detection
- EP260512a: EP-FXT follow-up observation
- GRB 260509A: SVOM/VT optical observations
- Konus-Wind detection of GRB 260511B
- The EP-WXT trigger 01709262036 is likely a flaring star
- EP260512a: COLIBRÍ optical upper limits
- EP260512a: Einstein Probe detection of an X-ray transient
- GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
- GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
- EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
- GRB 260511A: Glowbug gamma-ray detection
- Konus-Wind detection of GRB 260511A
- GRB 260510D: Glowbug gamma-ray detection of a likely short burst
- GRB 260511B: LCO optical counterpart detection
- GRB 260511B: GOTO optical counterpart detection
- GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
- GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 260511B: OSIRIS+/GTC redshift z=2.006