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"- LIGO/Virgo G184098: DESGW followup program
- LIGO/Virgo G184098: Pan-STARRS1 observations of the northern sky region
- LIGO/Virgo observing run 1 (O1) starts 2015-09-18 15:00 UTC
- LIGO/Virgo G184098: Keck II DEIMOS Spectra of iPTF Optical Candidates
- LIGO/Virgo G184098: Nearby Galaxies in Error Circle
- LIGO/Virgo G184098: Fermi-GBM ground-based follow-up
- LIGO/Virgo G184098: Observations from the TOROS collaboration
- LIGO/Virgo G184098: iPTF Optical Transient Candidates
- LIGO/Virgo G184098: VST-ESO PARANAL observations
- LIGO/Virgo G184098: Pan-STARRS1 observations of the northern sky region
- Instructions for reporting follow-up observations related to LIGO/Virgo G184098
- LIGO/Virgo G184098: observations by MASTER
- LIGO/Virgo G184098: TAROT La Silla Observatory optical observations (TZAC)
- LIGO/Virgo G184098: Swift follow-up observations
- LIGO/Virgo G184098: Burst candidate in LIGO engineering run data
- GRB 150915A: Swift-XRT refined Analysis
- GRB 150915A, Swift-BAT refined analysis
- GRB 150910A: AAO optical observations
- Konus-Wind observation of GRB 150911A
- GRB150915A : IRSF NIR upper limits
- GRB 000000: test of sernum on the original circular
- GRB 150915A: NOT observations of a brightening afterglow
- GRB 150915A: Swift UVOT upper limits
- GRB 150906B: Further analysis of the Konus-Wind data
- GRB 150910A: Mt. Terskol observatory optical observations
- GRB 150910A: TSHAO optical observations
- GRB 150915A: VLT/X-shooter redshift
- GRB 150915A: GROND detection of an optical counterpart candidate
- GRB 150915A: MASTER-NET optical observations
- GRB 150915A: Swift detection of a burst
- GRB 150910A: T100 observations
- GRB 150911A: GROND Upper Limits
- GRB 150910A: Continued RATIR Observations
- GRB 150907A: Swift-XRT afterglow detection
- GRB 150912A: Swift-XRT and UVOT observations
- GRB 150911A: Chuguev observatory upper limit
- GRB 150911A: Mt. Terskol observatory upper limit
- GRB 150911A: Khureltogot upper limit
- GRB 150910A: Mt. Terskol observatory optical observation
- Fermi GBM trigger 463890496/150914103 is not a GRB
- GRB 150912A: MITSuME Ishigakijima upper limits
- GRB 150911A: WHT optical imaging
- GRB 150910A: RATIR Observations
- GRB 150910A: MITSuME Ishigakijima Optical Observation after 2 days
- GRB 150912A: MASTER-IAC optical observations
- GRB 150912A: Fermi GBM observation
- GRB 150906B - NGC 3313 association: Constraints from Ep-Eiso and Ep-Liso Relations
- GRB 150912A: Swift ToO observations
- GRB 150906B: theoretical estimation of redshift and isotropic energy
- GRB150910A: P60 Observations
- GRB150911A: P60 Observations
- GRB 150911A: Swift/UVOT Upper Limits
- GRB 150911A: Swift-BAT refined analysis
- GRB 150912A: A long GRB detected by INTEGRAL
- GRB 150911A: Swift-XRT refined Analysis
- GRB 150910A: AAO optical observations
- GRB 150910A: MITSuME Ishigakijima Optical Observation after 1 day
- GRB 150910A: Chuguev observatory optical observations
- GRB 150911A: MITSuME Okayama upper limits
- GRB 150910A: VLA Detection
- GRB 150910A: continued SAO RAS optical observations
- GRB 150911A: Enhanced Swift-XRT position
- GRB150911A MITSuME Okayama Ks-band upper-limit
- GRB 150910A: TSHAO optical observations
- GRB 150911A: Swift detection of a burst
- GRB 150910A: NOT observations of the afterglow
- GRB 150910A: MITSuME Okayama Ks-band Observation
- GRB 150910A: GROND observation of the afterglow
- GRB 150910A: MITSuME Ishigakijima Optical Observation
- GRB 150910A: SAO RAS optical photometry
- GRB 150910A: Redshift from 10.4m GTC+OSIRIS
- GRB 150910A: Kast spectroscopy from 3m Shane telescope
- GRB 150910A: Swift-XRT refined Analysis
- GRB 150910A: Enhanced Swift-XRT position
- GRB 150910A: Swift/UVOT Detection of a Brightening Afterglow
- GRB 150910A: Nanshan optical observations
- GRB 150910A: Swift-BAT refined analysis
- GRB 150910A: MITSuME Okayama Optical Observation
- GRB 150910A: LCOGT FTN afterglow observations
- GRB 150910A: KAIT Optical Afterglow Detection
- GRB 150910A: Swift detection of a burst with an optical afterglow
- Short GRB 150906B: proximity to NGC 3313 galaxy group
- Swift Trigger 654954 is not an astrophysical event
- Fermi GBM trigger 463422723/150908689 is not a GRB
- GRB 150907B: Swift-XRT refined Analysis
- Konus-Wind observation of GRB 150906B
- IPN Triangulation of GRB 150906B (short/intense)
- Fermi GBM trigger 463339482/150907725 is too weak to be classified
- GRB 150907B: Swift-BAT refined analysis
- GRB150907A: Swift/UVOT observations
- GRB 150907B: MASTER-SAAO early optical observations
- GRB 150907B: Enhanced Swift-XRT position
- GRB 150907B: GROND Upper Limits
- GRB 150907B: Swift-XRT observations
- GRB 150907A: Swift-XRT observations
- GRB 150907B: Swift detection of a burst
- Fermi GBM trigger 150907763 is not a GRB
- GRB 150907A: Tiled Swift observations
- GRB 150907A: MAXI/GSC detection
- GRB 150906A: Fermi GBM detection