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').
- GRB 240710B: VZLUSAT-2 detection
- GRB 240805A: ATCA Radio Upper Limits
- Fermi trigger No 744761058: Global MASTER-Net observations report
- EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
- S240807h: Identification of a GW compact binary merger candidate
- EP-WXT trigger 01709018832: KAIT optical observations of the star flare
- EP240802a/GRB240802A: KAIT optical upper limit
- GRB 240720B: VZLUSAT-2 detection
- GRB 240710A: VZLUSAT-2 detection
- EP240806A: Liverpool Telescope optical follow-up observations
- The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
- GRB 240807A: Fermi GBM Final Localization
- EP240807a: EP-WXT detection of a fast X-ray transient
- EP240806a: Gemini North-GMOS spectroscopic redshift of z = 2.818
- GRB 240805B: GIT optical upper limit
- EP240806a: KAIT optical observations
- GRB 240805B: Swift-BAT refined analysis
- GRB 240805A: Swift-BAT refined analysis
- Fermi trigger No 744629911: Global MASTER-Net observations report
- EP240804a (GRB 240804B): NOT optical observations
- EP240806a: LCOGT optical counterpart detection
- Konus-Wind detection of GRB 240802A (EP240802a)
- Improved IPN triangulation of GRB 240802A / EP 240802a
- Konus-Wind detection of GRB 240805A
- GRB 240805B Bassano Bresciano Observatory upper limit
- GRB240805A: Fermi GBM Observation
- GRB 240805B: JinShan optical afterglow detection
- GRB 240804B/EP240804a: Correction to the GRB name in GCN 37071
- GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
- Konus-Wind detection of GRB 240804B (a counterpart of EP240804a)
- Fermi Gamma-ray Burst Monitor trigger 240806402/744629911 is not a GRB
- EP240806a: EP-FXT detection of the X-ray emission
- GRB 240626B: VZLUSAT-2 detection
- GRB 240624B: VZLUSAT-2 detection
- GRB 240619C: VZLUSAT-2 detection
- EP 240806A: LCO optical observations
- EP240806a: GSP optical counterpart detection
- EP240806a: EP-WXT detection of a fast X-ray transient
- GRB 240805B: Optical detection with 1.6m Mephisto
- EP240804a: BOOTES-6/DPRT optical detection
- GRB 240805B: NUTTelA-TAO / BSTI Optical Limits
- GRB 240805B: Swift-XRT refined Analysis
- Fermi trigger No 744544656: Global MASTER-Net observations report
- GRB 240805B: Swift/UVOT Upper Limits
- GRB 240805A: Swift/UVOT Upper Limits
- GRB 240805B: BTA optical afterglow candidate
- GRB 240805A: SVOM/GRM observation
- GRB 240805B: Enhanced Swift-XRT position
- GRB 240805B: LCOGT Optical Upper Limits
- Swift GRB 240805B: Global MASTER-Net observations report
- GRB 240805B: JinShan optical upper limits
- EP240801a: BTA BVRI photometry
- Fermi GRB 240805A: Global MASTER-Net observations report
- Swift GRB 240805A: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 744558410/240805574 is not a GRB
- GRB 240805A: Swift-XRT refined Analysis
- EP240804a: GSP detects optical candidate counterpart
- GRB 240805B: Swift detection of a burst
- GRB 240805A: Fermi-LAT detection
- GRB 240805A: INTEGRAL spectral analysis
- EP240801a: Continued optical observations at ZTSh (CraO)
- EP240804a: VLT/X-shooter spectroscopic redshift
- EP240804a: LCOGT optical counterpart detection
- GRB 240805A: A long GRB detected by INTEGRAL
- EP-WXT trigger 00109017646 is not a real source
- EP240804a: NOT optical counterpart detection
- EP240804a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
- EP240802a: correction of EP-WXT trigger time in GCN 37019
- GRB 240805A: Swift detection of a burst
- GRB 240805A: Fermi GBM Final Real-time Localization
- Fermi GRB 240804A: Global MASTER-Net observations report
- EP240802a: Montarrenti Observatory optical upper limit
- GRB 240804A: Fermi GBM Final Real-time Localization
- Fermi trigger No 744459130: Global MASTER-Net observations report
- IPN triangulation of GRB 240802A / EP 240802a
- Fermi Gamma-ray Burst Monitor trigger 744459130/240804425 is not a GRB
- EP240801a: Osservatorio Astronomico Nastro Verde upper limit
- EP240802A: Bassano Bresciano Observatory upper limit
- GRB 240802A: SVOM/GRM observation
- EP240802a: Time coincidence with GRB 240802A and optical upper limits with Kinder observations
- Fermi trigger No 744278264: Global MASTER-Net observations report
- EP240802a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
- GRB 240802A: AstroSat CZTI detection of a long burst
- EP240801a: further SAO RAS optical observations
- EP240801a: optical observations at CrAO and AbAO
- EP240801a: GRANDMA and Kilonova-Catcher optical observations
- EP240801a: Leavitt Observatory optical observations
- EP240801a: GTC spectroscopy and absorption redshift
- EP240801a: SAO RAS optical observations
- GRB 240801B: AstroSat CZTI Updated classification - likely a solar flare
- EP240801a: JinShan optical observations
- GRB 240727C: SVOM/GRM observation
- EP240801a: NOT optical observations
- EP240801a: follow-up observation with LCOGT
- Fermi GBM trigger 744179961 / 240801194 can not be confirmed as a GRB
- GRB 240730A: Swift-BAT refined analysis
- EP240801a: GSP follow-up observations of the candidate counterpart
- Fermi trigger No 744204856: Global MASTER-Net observations report
- EP240801a: Kinder follow-up observations of the candidate counterpart
- EP240708a: Kinder follow-up observations of the candidate counterpart (duplicate submission of GCN 37002)