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').
- EP241208a: EP detection of a fast X-ray transient
- GRB 241209A: Swift detection of a short burst
- Swift GRB241209.23: Global MASTER-Net observations report
- GRB 241209A: Fermi GBM Final Real-time Localization
- Fermi GRB 241207B: Global MASTER-Net observations report
- GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
- Fermi Gamma-ray Burst Monitor trigger 755277791/241207641 is not a GRB
- GRB 241201A: AstroSat CZTI detection
- GRB 241206A: DDOTI Upper Limit on the Afterglow
- AT2024adec: X-ray Upper Limits from EP-FXT Observation
- AT2024adec: X-ray Upper Limits from EP-FXT Observation
- EP241206a: BOOTES Global Network optical limits
- GRB 241207C: MASTER optical observations
- Fermi trigger No 755225799: Global MASTER-Net observations report
- GRB 241207C: Tiled Swift observations
- GRB 241207C: MAXI/GSC detection
- GRB 241207B: Fermi GBM Final Real-time Localization
- Fermi trigger No 755277791: Global MASTER-Net observations report
- Fermi GRB 241207A: Global MASTER-Net observations report
- EP241206a: Global MASTER-Net observations report
- EP241206a: EP detection of a fast X-ray transient
- GRB 241206A: Fermi GBM observation
- GRB 241206C: SVOM/GRM observation of a likely short burst
- GRB 241207A: Fermi GBM Final Real-time Localization
- GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
- GRB 241206B: SVOM/MXT observations: a probable flare from the QSO 1ES 1959+650
- GRB 241206B: GWAC-F50A optical upper limit
- GRB 241206B: SVOM/ECLAIRs detection of a long soft transient
- EP241113a: Keck/LRIS spectroscopic observation and tentative redshift
- Fermi GRB 241206A: Global MASTER-Net observations report
- GRB 241206A: Fermi GBM Final Real-time Localization
- EP241201a: 1.6m Mephisto Optical Upper Limits
- GRB 241204A: COLIBRÍ Optical Upper Limit
- EP241202b: KAIT optical upper limit
- LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
- GRB 241204A: DDOTI Upper Limits on the Afterglow
- GRB 241204A: Fermi GBM Observation
- Fermi GRB 241204A: Global MASTER-Net observations report
- GRB 241130A: CALET Gamma-Ray Burst Monitor detection
- GRB 241128A : RAPAS follow-up observations
- GRB 241201A: GRBAlpha detection
- GRB 241204A: Fermi-LAT detection
- EP241202b: Upper limits from Fermi-GBM Observations
- IceCube-241127A: No transient candidates from the Zwicky Transient Facility
- EP241202b: Kinder optical counterpart candidate
- Fermi-GBM Sub-Threshold Detection of GRB 241128A
- GRB 241113B : RAPAS follow-up observation
- EP241201a: EP-FXT follow-up observations
- Konus-Wind detection of GRB 241130A
- EP241202b: Global MASTER-Net observations report
- EP241201a: BOOTES-5 optical upper limit
- EP241202b: EP detection of a fast X-ray transient
- EP241201a: NOT optical observations
- IPN triangulation of GRB 241130A
- GRB 241130A: EIRSAT-1 GMOD Detection
- GRB 241128A: Swift/UVOT Upper Limits
- GRB 241130A: Fermi GBM Detection
- IceCube-241127A: Upper limits from a search for additional neutrino events in IceCube
- GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
- EP241201a: Kinder optical counterpart candidate
- LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
- EP241201a: Global MASTER-Net observations report
- EP241201a: EP detection of a fast X-ray transient
- The EP-WXT trigger 01709126243 is not a real source
- GRB 241127B: detection of a long GRB by SVOM/ECLAIRs
- GRB241201B: Fermi GBM Final Localization
- GRB241201B: Fermi GBM Final Localization
- LIGO/Virgo/KAGRA S241201ac: Updated Sky localization
- EP241126a: SOAR observations of the optical counterpart
- Fermi GRB 241201A: Global MASTER-Net observations report
- GRB 241201A: BALROG localization (Fermi Trigger 754757764 / GRB 241201622)
- GRB 241130A: Fermi GBM Final Real-time Localization
- GRB 241130A: Fermi GBM Final Real-time Localization
- EP241126a: 1.6m Mephisto Optical Upper Limits
- GRB 241201A: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241130be: Updated Sky localization
- Fermi trigger No 754701230: Global MASTER-Net observations report
- IPN triangulation of GRB 241128B
- Konus-Wind detection of GRB 241114B
- LIGO/Virgo/KAGRA S241130n: Updated Sky localization
- LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
- GRB 241128A: AbAO optical upper limit
- LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
- LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241129aa: Updated Sky localization
- LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
- SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
- GRB 241128C: SVOM/GRM observation
- GRB 241128B: SVOM/GRM observation
- GRB 241128A: Swift-BAT refined analysis
- GRB 241127A: Swift-BAT refined analysis
- EP241126a: NOT optical observations
- GRB 241127A: PRIME near-infrared detection
- GRB 241128A: Mondy optical observations
- GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
- Swift-XRT observations of IceCube -241127A
- Swift GRB 241128A: Global MASTER-Net observations report
- Fermi-LAT gamma-ray observations of IceCube-241127A
- EP241126a: SVOM/VT observations