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"
820 results found.
- EP#01709175213/IGR J19566+0326: Swift-XRT detection
- EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
- GRB 250331A: MAXI/GSC detection
- IceCube Alert 250330.35: Global MASTER-Net observations report
- EP250311a/GRB 250311A: Correction to EP-WXT detection time
- EP250311a/GRB 250311A: EP-FXT follow-up observation
- GRB 250311A: Swift-XRT observations
- GRB 250311A/EP250311a: TRT optical upper limit
- GRB 250311A: Tiled Swift observations
- EP250311a/GRB 250311A: EP-WXT detection
- GRB 250311A/MAXI J1457-026: MAXI/GSC detection
- GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
- GRB 250207B: Swift-XRT observations
- GRB 250207B: Tiled Swift observations
- GRB 250207B: MAXI/GSC detection
- LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
- GRB 250129A: Swift-BAT refined analysis
- LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
- GRB 250126A: CALET Gamma-Ray Burst Monitor detection
- GRB 250126A: MAXI/GSC detection
- GRB 250101A NUTTelA-TAO / BSTI Early Measurements
- LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
- Integral GRB241215.58: Global MASTER-Net observations report
- GRB 241213B: Swift-XRT observations
- GRB 241213B: Tiled Swift observations
- GRB 241213B: CALET Gamma-Ray Burst Monitor detection
- GRB 241213B: MAXI/GSC detection
- GRB 241207C: MASTER optical observations
- GRB 241207C: Tiled Swift observations
- GRB 241207C: MAXI/GSC detection
- LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
- GRB 241030A: Swift/UVOT Detection
- LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S240830gn: Coverage and upper limits from MAXI/GSC observations
- GRB 240824B: Ondrejov D50 optical limit
- GRB 240824B: Fermi GBM Observation
- GRB 240824B: Swift-XRT afterglow detection
- GRB 240824B: Swift/BAT arcminute localization of a burst
- GRB 240824B: MAXI/GSC detection
- GRB 240809B: MAXI/GSC detection
- LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
- GRB 240514E: A possible candidate BD-21 1074
- MAXI GRB240514.78: Global MASTER-Net observations report
- GRB 240514E: MAXI/GSC detection of a probable afterglow
- LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
- GRB 240309A: MAXI/GSC detection
- GRB 240225B: Swift-XRT afterglow detection
- GRB 240225B: Glowbug gamma-ray detection
- GRB 240225B: Swift ToO observations
- Konus-Wind detection of GRB 240225B (long)
- GRB 240225B: VLT/X-shooter redshift
- GRB 240225B : MITSuME Akeno optical afterglow candidate detection
- GRB 240225B: 3.6m DOT observation
- GRB 240225B: NOT optical observations
- GRB 240225B: Nanshan/HMT optical afterglow detection
- GRB 240225B: CALET Gamma-Ray Burst Monitor detection
- GRB 240225B: Swift-XRT observations
- GRB 240225B: GOTO detection of a candidate optical afterglow
- GRB 240225B: AstroSat CZTI detection
- GRB 240225B: Tiled Swift observations
- GRB 240225B: MAXI/GSC detection
- GRB 240128A: Further Swift-XRT observations
- GRB 240214A: Tiled Swift observations
- GRB 240214A/1H 0451-560: MAXI/GSC detection
- GRB 240128A: Glowbug gamma-ray detection
- GRB 240128A: Swift-XRT observations
- GRB 240128A: GRBAlpha detection
- GRB 240128A: Tiled Swift observations
- GRB 240128A: CALET Gamma-Ray Burst Monitor detection
- GRB 240128A: MAXI/GSC detection
- GRB 240122A: ATCA detection of radio counterpart
- GRB240122A: PRIME near infrared detection
- GRB 240122A: Swift/UVOT Upper Limits
- GRB 240122A: BOOTES-2/TELMA optical upper limit and 1.5m OSN detection
- GRB 240122A: Swift-XRT afterglow detection
- GRB 240122A: VLT/X-shooter redshift confirmation
- GRB 240122A: Redshift from OSIRIS+/GTC
- GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
- GRB 240122A: GOTO optical counterpart candidate
- GRB 240122A: Tiled Swift observations
- GRB 240122A: MAXI/GSC detection
- GRB 240107A: VZLUSAT-2 detection
- GRB 240114A: MAXI/GSC detection
- GRB 240107A: AstroSat CZTI detection
- GRB 240107A: MAXI/GSC detection
- IPN triangulation of GRB 231129C
- GRB 231129C: ASIM MXGS observation and localization
- Konus-Wind detection of GRB 231129C
- GRB 231129C: PROMPT optical upper limits for the MAXI/GSC X-ray counterpart and the MASTER afterglow candidate
- GRB 231129B: Swift-XRT observations
- GRB 231129C: AGILE detection
- GRB 231129C: Swift/BAT-GUANO localization of a burst outside the coded FOV
- GRB 231129C: MASTER OT detection
- GRB 231129C: Fermi-LAT detection
- GRB 231129C: GRBAlpha detection
- GRB 231129C: Glowbug gamma-ray detection