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"
58 results found.
- sb25061207: Mephisto optical upper limits
- GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
- GRB 250515A: 1.6m Mephisto optical detection
- EP250511a: Mephisto optical upper limits
- GRB 250506A: Mephisto optical upper limits
- GRB 250419A: Mephisto Multi-band Optical Detection
- EP250421a: Mephisto optical counterpart confirmation
- EP250404a: Mephisto multi-band optical detection
- GRB 250403A: 1.6m Mephisto multi-band optical detection
- GRB 250327B: Kilonova-Catcher Observations
- GRB 250329B: CAHA 2.2m telescope optical limit
- GRB 250328A: 1.6m Mephisto optical observations
- GRB 250329B: 1.6m Mephisto Optical Upper Limits
- GRB 250327B: MASTER detection of OT rebrightening
- GRB 250327B: 1.6m Mephisto optical observations
- EP250308a: 1.6m Mephisto optical upper limits
- GRB 250226A: GRANDMA Optical Observations
- GRB 250226A: Fermi GBM Observation
- EP250226a/GRB 250226A: 1.6m Mephisto observations
- EP250223a: 1.6m Mephisto and 50cm array observations
- GRB 250221A: 1.6m Mephisto optical detection
- EP250220a: 1.6m Mephisto observations
- GRB 250219A: 1.6m Mephisto optical upper limits
- GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
- EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
- GRB 250109A / EP250109a: Mephisto optical upper limits
- EP250108a: Mephisto detection
- GRB 250103A: 1.6m Mephisto optical observations
- GRB 241228B: Fermi-LAT detection
- GRB 250101A: 1.6m Mephisto multi-band optical followup
- GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
- EP241217a: 1.6m Mephisto multi-band optical observations
- GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
- EP241201a: 1.6m Mephisto Optical Upper Limits
- EP241126a: 1.6m Mephisto Optical Upper Limits
- EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
- GRB 241112B: Mephisto further optical observations
- GRB 241115A: Mephisto upper limits
- GRB 241113B: Mephisto upper limits
- GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
- GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
- GRB 241112B: Mephisto optical upper limits
- EP241021a: Optical rebrightening observations with Mephisto
- GRB 241030A: Multiband optical detection with Mephisto
- GRB 241029A: GOTO optical afterglow detection
- GRB 241029A: Mephisto observations
- GRB 241018A/sb24101802: Mephisto optical upper limit
- GRB 241017A/sb24101702: Mephisto optical upper limit
- EP240913a/GRB 240913C: 1.6m Mephisto observations
- EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
- GRB 240828B: Mephisto optical upper limit
- GRB 240825A: MASTER optical counterpart observation
- GRB 240825A: 1.6m Mephisto multi-band detection
- GRB 240811A: Upper limits with Mephisto
- GRB 240805B: Optical detection with 1.6m Mephisto
- LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
- GRB231111A: MDM 2.4m Hiltner Telescope Observation
- GRB231111A: Optical follow-up observations with Mephisto