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"

20350 results found.

  1. GRB 260925A: Swift/UVOT Upper Limits
  2. Konus-Wind detection of GRB 260924A
  3. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  4. GRB 260924A: Optical follow-up observations with Kinder
  5. GRB 260925A: Enhanced Swift-XRT position
  6. GRB 260925A: COLIBRÍ optical upper limits
  7. GRB 260925A: FRAM-Auger optical limit
  8. GRB 260924A: Ondrejov D50 optical afterglow detection
  9. EP260924a: J-band upper limit with WINTER
  10. GRB 260924A: SVOM/GRM observation
  11. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  12. GRB 260925A: Swift detection of a burst
  13. EP260924a: EP-WXT detection of an X-ray transient
  14. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  15. GRB 260924A: Swift/UVOT Detection
  16. GRB 260924A: GROWTH-India Telescope optical observations
  17. GRB 260921A: SVOM/GRM observation
  18. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  19. GRB 260924A: Fermi GRB Observation
  20. GRB 260920A: SVOM/GRM observation
  21. GRB 260924A: NOT optical counterpart confirmation
  22. GRB 260924A: Enhanced Swift-XRT position
  23. GRB 260924A: Swift detection of a burst
  24. EP260806a: e-MERLIN detection at 5 GHz
  25. GRB 260922A: Ondrejov D50 optical limit
  26. ATCA observations of GRB 260909A
  27. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  28. GRB 260922A: J-band upper limit with WINTER
  29. GRB 260922A: Swift/UVOT Upper Limits
  30. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  31. GRB 260922A: COLIBRÍ optical upper limits
  32. GRB 260922A: Enhanced Swift-XRT position
  33. GRB 260918A: SVOM/ECLAIRs refined analysis
  34. GRB 260922A: SVOM/C-GFT optical upper limit
  35. GRB 260922A: Swift detection of a burst
  36. GRB 260917C: AstroSat CZTI detection
  37. GRB 260921A: AstroSat CZTI detection
  38. GRB 260917B:: SVOM/ECLAIRs refined analysis
  39. EP260920a: VLT/HAWK-I near-infrared candidate
  40. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  41. EP260920b: LCO observations
  42. GRB 260920A: AstroSat CZTI detection
  43. EP260920b: SVOM/VT optical observation
  44. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  45. EP260920b: COLIBRÍ optical observations
  46. EP260920b: LCO optical counterpart detection
  47. EP260920b: Einstein Probe detection of an X-ray transient
  48. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  49. EP-WXT detected a brightening of HMXB LS V +44 17
  50. EP260920a: NOT early time optical upper limits
  51. EP260920a: NOT optical upper limits
  52. EP260920a: SVOM/VT optical upper limits
  53. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  54. EP260920a: COLIBRÍ optical upper limits
  55. EP260920a: LCO optical counterpart candidate
  56. EP260920a: Einstein Probe detection of an X-ray transient
  57. GRB 260915A: VLT optical and near-infrared upper limits
  58. EP260917a: SVOM/VT optical upper limits
  59. GRB 260918A: SVOM/C-GFT optical upper limits
  60. Fermi GBM Sub-Threshold Detection of GRB 260918A
  61. GRB 260917B: Mondy optical upper limit
  62. IPN triangulation of GRB 260916B (short)
  63. EP260917b: EP-WXT detection of an X-ray transient
  64. EP260917A: J-band upper limit with WINTER
  65. GRB 260917B: EP-FXT follow-up observation
  66. EP260917a: COLIBRÍ optical upper limits
  67. GRB 260918A: LCO optical upper limits
  68. EP260917a: Einstein Probe detection of an X-ray transient
  69. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  70. GRB 260918A: SVOM detection of a burst
  71. GRB 260917B: FRAM-Auger optical limits
  72. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  73. GRB 260915A: SVOM/ECLAIRs refined analysis
  74. GRB 260917B: WINTER J-band observations
  75. GRB 260917B: SVOM/VT optical observations
  76. GRB 260917B: LCO optical observation
  77. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  78. GRB 260917B: SVOM detection of a faint burst
  79. GRB 260915A: J-band upper limit with WINTER
  80. GRB 260909A: NOEMA detection
  81. GRB 260914A: SVOM/GRM observation
  82. GRB 260914A: Mondy and TShAO optical observations
  83. GRB 260914A: SVOM/ECLAIRs refined analysis
  84. GRB 260909A: Swift-XRT observations
  85. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  86. GRB 260915A: SVOM/C-GFT optical upper limits
  87. GRB 260915A: REM optical/NIR observations
  88. GRB 260914A: REM optical/NIR observations
  89. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  90. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  91. GRB 260915A: NOT optical upper limit
  92. GRB 260915A: SVOM/VT optical upper limits from VHF data
  93. GRB 260915A: LCO optical upper limits
  94. EP Alert 260914.53: Global MASTER-Net observations report
  95. GRB 260915A: SVOM detection of a burst
  96. GRB 260914A: LCO optical observation
  97. GRB 260914A: SVOM/C-GFT optical observations
  98. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  99. GRB 260914A: SVOM detection of a burst
  100. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event

Advanced

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