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').
10043 results found.
- GRB 240916A (AT 2024vlp / GOTO24fzn): VLT/X-shooter redshift
- LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
- LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
- GRB 240905E: further NOT optical observations
- EP240913a: A GRB Event
- EP240913a: EP-WXT detection of a fast X-ray transient
- GRB 240912A: Redshift from OSIRIS+/GTC
- GRB 240910A: Redshift from OSIRIS+/GTC
- EP240908a: Optical afterglow confirmation
- GRB 240910A: GRBAlpha detection
- LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
- EP240908a: Mondy and AbAO follow-up observations
- EP240908a: optical afterglow candidate
- EP240908a: EP detection of a fast X-ray transient
- GRB 240905B: Fermi-LAT detection
- GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
- GRB 240825A: TSHAO Optical Upper Limit
- GRB 240829B: GRBAlpha detection
- GRB 240828B: AbAO optical upper limit
- GRB 240828B: GRANDMA Optical Upper Limit
- LIGO/Virgo/KAGRA S240830gn: Coverage and upper limits from MAXI/GSC observations
- GRB 240828A: Fermi-LAT detection
- GRB 240819A as a likely X-Ray Flash
- SVOM GRB 240821A: optical afterglow discovery
- GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
- GRB 240825A: GECAM detection
- GRB 240825A: Fermi GBM Observation
- GRB 240825A: Swift/UVOT Detection
- GRB 240825A: Fermi-LAT detection
- GRB 240824B: Swift/BAT arcminute localization of a burst
- GRB 240824A: Swift/UVOT Upper Limits
- GRB 240824B: MAXI/GSC detection
- GRB240824A: GRANDMA/TAROT-TCA Upper Limit
- GRB 240809A: Mondy and AbAO Optical Observations
- GRB240821B: First GRB Detected by EIRSAT-1 GMOD
- GRB 240821A: EP-FXT follow-up observation and afterglow candidates
- GRB 240821A: GRANDMA/LesMakes-T60 Upper Limit
- EP240820a: EP detection of a fast X-ray transient
- GRB 240819A: TRT optical upper limits on the Swift/XRT and EP/FXT sources
- GRB 240819A: X-ray follow-up observation with EP-FXT
- IBAS Alert n.10856: not a GRB
- GRB 240814B: GRBAlpha detection
- EP240816a: EP detection of a fast X-ray transient and follow-up observation
- EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
- EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
- GRB 240809A : RAPAS follow-up observations
- GRB 240811A: Bassano Bresciano Observatory upper limit
- GRB 240811A: Swift/UVOT Upper Limits
- EP240801a: Assy-Turgen optical observations
- GRB 240809A: Conclusive redshift from VLT
- GRB 240809B: MAXI/GSC detection
- GRB 240801A: GRBAlpha detection
- GRB 240710B: VZLUSAT-2 detection
- EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
- GRB 240720B: VZLUSAT-2 detection
- GRB 240710A: VZLUSAT-2 detection
- The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
- EP240807a: EP-WXT detection of a fast X-ray transient
- GRB 240805B Bassano Bresciano Observatory upper limit
- GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
- EP240806a: EP-FXT detection of the X-ray emission
- GRB 240626B: VZLUSAT-2 detection
- GRB 240624B: VZLUSAT-2 detection
- GRB 240619C: VZLUSAT-2 detection
- EP240806a: EP-WXT detection of a fast X-ray transient
- GRB 240805B: BTA optical afterglow candidate
- EP240801a: BTA BVRI photometry
- EP240801a: Continued optical observations at ZTSh (CraO)
- EP240804a: VLT/X-shooter spectroscopic redshift
- EP240804a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
- EP240802a: Time coincidence with GRB 240802A and optical upper limits with Kinder observations
- EP240802a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
- EP240801a: optical observations at CrAO and AbAO
- EP240801a: GRANDMA and Kilonova-Catcher optical observations
- EP240801a: Leavitt Observatory optical observations
- EP240801a: Kinder follow-up observations of the candidate counterpart
- EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
- GRB 240727C: GRBAlpha detection
- LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
- GRB 240727A: Swift/UVOT detection
- GRB 240720B: GRBAlpha detection
- GRB 240718A: GRBAlpha detection
- GRB 240710B: GRBAlpha detection
- GRB 240627A: GRBAlpha detection
- GRB240529A: VIRT optical transient detection
- IceCube-Cascade 240714A: X-ray follow-up observation with EP-FXT
- GRB240715A: GRANDMA Optical Upper Limits
- GRB 240712A: Swift/UVOT Upper Limits
- The EP-WXT source triggered on July 14th is likely a flaring star
- GRB 240713A: NOT optical upper limits on three EP/FXT candidates
- GRB 240713A: JinShan optical upper limits
- GRB240713A: X-ray follow-up observation with EP-FXT
- Fermi Sub-threshold Observation of GRB240713A
- GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
- GRB 240712A: Swift detection of a burst
- LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
- EP240708a: NOT optical observations
- EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
- EP240708a: EP-WXT detection of a fast X-ray transient
- LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources