Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

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').
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"

2793 results found.

  1. GRB 251116D: SVOM/GRM observation of a long GRB
  2. GRB 251119A: SVOM detection of a possible burst
  3. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  4. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  5. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  6. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  7. Swift Trigger 1413695: a possible GRB 251112A
  8. IPN triangulation of GRB 251105B (possible sGRB with EE)
  9. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  10. Konus-Wind detection of GRB 251028A
  11. GRB 251026B: SOAR Classification of GOTO25jgl/SN2025absf as a Type Ia supernova
  12. GRB 251026B: Tentative GOTO optical counterpart candidate
  13. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  14. IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
  15. IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
  16. Swift Trigger 1404295: possible GRB 251015A
  17. IceCube-251014A - IceCube observation of a high-energy neutrino candidate track-like event
  18. GRB 251013C: OHP/T193 further optical observations and possible color evolution
  19. MASTER OT J011025.98-583210.6 : SVOM/VT optical observation
  20. GRB 251009A: SVOM/GRM observation of short GRB with possible tail emission
  21. IceCube alert 141456_888784 retraction
  22. GRB 251006A (short): Glowbug gamma-ray detection
  23. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  24. GRB 251001B: COLIBRÍ optical observations
  25. GRB 250910A / EP250910a: VLT limits on the possible associated supernova
  26. GRB 250926A: triangulation location with Insight-HXMT/HE and Fermi/GBM
  27. IceCube-250926A - IceCube observation of a high-energy neutrino candidate track-like event
  28. GRB 250926A: DDOTI Optical Observations and Spatial Coincidence with the Orion Nebula
  29. GRB250912A: VLT/HAWK-I follow-up observations
  30. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  31. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  32. GRB 250910A: SVOM/MXT possible afterglow detection
  33. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  34. EP250827b: Swift observations of AT 2025wkm
  35. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  36. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  37. LIGO/Virgo/KAGRA S250818k: VLA upper limits on AT2025ulz
  38. LIGO/Virgo/KAGRA S250818k: nature of the AT2025ulz/ZTF25abjmnnps OT
  39. LIGO/Virgo/KAGRA S250818k: FTW Observations Show Continued Reddening of AT 2025ulz
  40. LIGO/Virgo/KAGRA S250818k: Swift Observations of AT 2025ulz - Second Epoch
  41. LIGO/Virgo/KAGRA S250818k: CFH/MegaCam follow-up observation for AT2025ulz
  42. LIGO/Virgo/KAGRA S250818k: HST nIR detection of AT 2025ulz
  43. LIGO/Virgo/KAGRA S250818k: J-GEM follow-up observation for AT2025ulz
  44. LIGO/Virgo/KAGRA S250818k: Pan-STARRS coverage of the skymap and candidate counterparts
  45. LIGO/Virgo/KAGRA S250818k: EP/FXT observation of AT 2025ulz
  46. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  47. LIGO/Virgo/KAGRA S250818k: WINTER J-band observations of AT 2025ulz
  48. LIGO/Virgo/KAGRA S250818k: Swift observations of AT 2025ulz
  49. LIGO/Virgo/KAGRA S250818k: ATLAS pre-discovery limits for AT2025ulz
  50. GRB 250814A: Further COLIBRÍ optical upper limit
  51. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  52. GRB 250814A: Possible afterglow candidate from P200/WIRC
  53. IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
  54. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  55. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  56. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  57. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  58. Swift Trigger 1334535: a possible GRB 250718A
  59. GRB 250716A: GOTO tentative optical counterpart candidate
  60. GRB 250713A: NOT optical upper limits
  61. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  62. IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
  63. IceCube-250706A - IceCube observation of a high-energy neutrino candidate track-like event
  64. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  65. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  66. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  67. GRB 250702F: Ondrejov D50 optical afterglow detection
  68. GRB 250628A: REM optical/NIR upper limits
  69. GRB 250625A: SAO RAS possible optical afterglow
  70. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  71. sb25061207: SVOM detection of a X-ray transient
  72. GRB 250610B: REM optical/NIR observations
  73. GRB 250610B: SVOM/VT optical shallow decay
  74. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  75. EP250610a: REM optical/NIR observations
  76. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  77. GRB 250605A: SVOM/VT optical upper limit
  78. GRB 250605A: LT optical observations
  79. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  80. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  81. GRB 250530C: Swift detection of a burst
  82. GRB 250521C (short): Zwicky Transient Facility identification of a possible fast optical transient counterpart
  83. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  84. GRB 250520A: REM optical/NIR early observations
  85. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  86. GRB 250424A: COLIBRÍ detection of the associated supernova
  87. EP250512a/GRB 250512B: REM optical/NIR observations
  88. EP250511a: REM optical/NIR observations
  89. EP250511a: SVOM/VT optical candidate comfirmation
  90. EP250511a: COLIBRÍ optical counterpart candidate
  91. GRB 250510A: follow-up observation with EP-FXT
  92. GRB 250510A: SVOM possible detection of a burst
  93. EP250508a: REM optical/NIR observations
  94. GRB 250507A: REM optical/NIR observations
  95. IceCube-250506A - IceCube observation of a high-energy neutrino candidate track-like event
  96. GRB 250506A: REM optical/NIR upper limits
  97. GRB 250506A: Swift XRT observations and possible counterpart detection
  98. EP250428b: Pan-STARRS follow-up, upper limit on the optical counterpart, and possible host galaxy.
  99. IceCube-250429A - IceCube observation of a high-energy neutrino candidate track-like event
  100. EP250427a: Lesedi optical counterpart detection

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov