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"- GRB040106, follow-up radio observations
- GRB040106: refined X-ray transient position
- Follow-up on IBAS GRB Alert 1379
- IBAS GRB alert 1379
- SN 2003dh/GRB030329 late-time optical spectroscopy
- GRB040106, Radio Observations
- GRB040106, likely optical afterglow
- GRB040106: Second Epoch Optical Observations
- GRB 031220: Optical observations of Chandra X-ray sources
- XMM-Newton Images of GRB 040106
- GRB040106: optical observations with REM+ROSS
- GRB031220: observation at Univercity of Miyazaki
- GRB 040106: Optical observations
- XMM-Newton observation of GRB040106
- GRB 040106 : Planned XMM-Newton observation
- GRB 040106 : peak flux
- GRB 040106 : a long GRB detected with INTEGRAL
- IPN triangulation of an intermediate burst from SGR1806-20
- GRB031220(=H2976): TNG R-band Observation of the Chandra X-ray Sources
- GRB031220(=H2976): Observation with the Chandra X-ray Observatory
- GRB031225a triangulation (annulus)
- IPN triangulation of GRB031219 (large error box)
- GRB031220: Palomar Observations
- GRB 031220 : Kyoto Optical Observation
- GRB 031220: Subaru observation
- GRB 031220: Optical observation at Tokyo Tech
- GRB031220: ROTSE-IIIb Optical Limits
- GRB031220 : Optical Observation of Lulin Observatory
- GRB 031203 I-band monitoring
- IPN triangulation of GRB031214 (short/hard; very intense; small error box)
- GRB 2974 follow-up observations
- GRB031203, improved XMM position
- GRB 031203: Discovery of a dust echo
- GRB031214 triangulation (annulus), [repost of GCN2487, subject corrected]
- GRB030921 triangulation (annulus)
- GRB 031203: SMARTS optical monitoring
- GRB 021203: A Normal GRB viewed far off axis?
- XMM-Newton Observations of GRB031203: Preliminary Images
- GRB 031203: Variable Radio Source
- GRB 031203: Magellan spectrum of possible GRB host
- GRB 031203: Optical/IR Astrometry
- IPN/HETE localization of GRB031203B (=H2949; large error box)
- GRB031203 K prime photometry: correction to galaxy coordinates
- GRB031203: ROSAT upper limits suggest XMM-S1 source as the transient
- XMM-Newton Observation of GRB031203
- GRB 031203: Deep NIR NTT & VLT observations
- GRB031203: K' Photometry of the likely GRB host
- XMM-Newton Observation of GRB031203
- GRB 031203: Radio detection
- GRB 031203: Further reports on December 4 observations
- GRB 031203: IR NTTobservations do not confirm REM detection
- GRB031203 : Optical Observation of Lulin Observatory
- GRB 031203: z ~ 10 or Fragmented Dust in the Circumburst Environment?
- GRB 031203: Apparent Spectral Break
- GRB031203: Planned XMM-Newton observation II
- GRB 031203: IR REM Observations
- GRB031203: Optical Observations
- GRB 031203 XMM-Newton observation
- GRB 031203: Optical/IR SMARTS Observations
- GRB031203: Planned XMM-Newton observation
- IPN triangulation of GRB031127A and B (quasi-simultaneous; large error boxes)
- GRB 031203: further analysis of INTEGRAL data
- GRB 031203: A long GRB detected with INTEGRAL
- IPN triangulation of GRB031201 (large error box)
- IPN triangulation of GRB031130 (large error box)
- GRB031111A, prompt optical observations
- GRB 030329: Planned XMM-Newton Observation
- IPN triangulation of GRB031120 (two large error boxes)
- GRB 031111B (= H2925) : Kyoto Optical Observation
- IPN/HETE localization of GRB031109 (=H2917; large error box)
- IPN detection of activity from SGR1806-20
- GRB 031111, Radio observations
- IPN triangulation of GRB031114 (large error box)
- IPN triangulation of GRB031107 (two large error boxes)
- GRB 031111: Optical observations
- GRB 031111, optical observations
- SN 2003jd (SN/GRB?) -- X-ray Observations
- HETE Prompt GRB Spectral Analyses
- IPN triangulation of GRB031111 (=H2924): small error box
- XRF031109 (=H2919): A very long XRF localized by HETE
- IPN triangulation of GRB031108 (large error box)
- GRB031026: 1.2mm upper limit with MAMBO at the IRAM 30m
- GRB030929/SN2003jd association unlikely based on IPN localiztion
- IPN triangulation of GRB031027 (small error box)
- IPN triangulation of GRB031026B (large error box)
- Lulin optical follow-up observations of GRB031026
- SN 2003jd (SN/GRB?), Radio Observations
- SN 2003jd (SN/GRB?) - possible association with GRB 030929
- GRB 031026: Further Ic Observations
- GRB 031026 (=H2882): Evidence for High Redshift from Prompt
- Peculiar Type Ic SN 2003jd (SN/GRB?), optical spectrum
- IPN triangulation of GRB031024 (single error box)
- GRB031026 (=H2882): A Long, Hard Spectrum Burst Localized by HETE
- GRB 031026: Ic Observations
- GRB031026 : KISO optical follow-up observation
- IPN triangulation of GRB031024 (annulus)
- IPN triangulation of GRB031020 (large error box)
- GRB030329: radio observations at RT-22 (CrAO)
- IPN triangulation of GRB031016 (two large error boxes)
- IBAS alert 1180 refers to a burst from SGR 1806-20