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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"

648 results found.

  1. Konus-Wind detection of GRB 260924A
  2. GRB 260922A: Swift-BAT refined analysis
  3. GRB 260921A: AstroSat CZTI detection
  4. GRB 260921A: Swift-BAT refined analysis
  5. EP260920a: COLIBRÍ optical upper limits
  6. EP Alert 260918.24: Global MASTER-Net observations report
  7. SVOM GRB260918.16: Global MASTER-Net observations report
  8. Fermi GRB 260805A: Global MASTER-Net observations report
  9. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  10. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  11. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  12. GRB 260616A: AstroSat CZTI detection
  13. GRB 260616A: SVOM/GRM observation
  14. Fermi GRB 260523A: Global MASTER-Net observations report
  15. EP260509a: Global MASTER-Net observations report
  16. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  17. GRB 260321A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  18. Fermi GRB 260310B: Global MASTER-Net observations report
  19. Fermi GRB 260221A: Global MASTER-Net observations report
  20. Fermi GRB 260219A: Global MASTER-Net observations report
  21. EP260209a: Global MASTER-Net observations report
  22. Fermi GRB 260208C: Global MASTER-Net observations report
  23. GRB 260208B: Fermi GBM Detection
  24. Konus-Wind detection of GRB 260128A / EP260128a
  25. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  26. EP260119a: SVOM/VT optical observation
  27. Swift trigger on the HMXB 1A 1118-61
  28. Swift triggered on the HMXB 1A 1118-61
  29. IceCube Alert 260111A: Global MASTER-Net observations report
  30. Swift GRB 251214B: Global MASTER-Net observations report
  31. SVOM GRB251211.12: Global MASTER-Net observations report
  32. GRB 251208A: SVOM/GRM observation of a short burst
  33. Fermi GRB 251127A: Global MASTER-Net observations report
  34. Fermi trigger No 784279167: Global MASTER-Net observations report
  35. GRB 251103A: NOT spectroscopic redshift z = 0.76
  36. Fermi GRB 251013A: Global MASTER-Net observations report
  37. GRB 250909A: AstroSat CZTI detection
  38. EP250901a: Mondy, Assy and SAO RAS optical limits
  39. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  40. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  41. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  42. GRB 250831A: Swift-XRT counterpart detection
  43. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  44. GRB 250831A: SVOM/VT upper limit with VHF data
  45. EP250711a: COLIBRÍ continuous optical observations
  46. IceCube-250708A: Global MASTER-Net observations report
  47. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  48. EP250610a: Global MASTER-Net observations report
  49. GRB 250516A: Swift-BAT refined analysis
  50. MAXI GRB250515.65: Global MASTER-Net observations report
  51. GRB 250430A: Swift-BAT refined analysis
  52. Fermi GRB 250502B: Global MASTER-Net observations report
  53. Fermi-LAT gamma-ray observations of IceCube-250421A
  54. GRB 250327A: Swift-XRT refined Analysis
  55. GRB 250327A: SVOM/VT optical candidate
  56. GRB 250322A: AstroSat CZTI detection of a short burst
  57. Fermi trigger No 763509110: Global MASTER-Net observations report
  58. Fermi GRB 250309B: Global MASTER-Net observations report
  59. GRB 250226A: Fermi GBM Observation
  60. Fermi GRB 250223A: Global MASTER-Net observations report
  61. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  62. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  63. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  64. GRB 250207A: REM IR afterglow detection
  65. GRB 250207A: REM optical afterglow detection
  66. GRB 250114B: OHP/T193 optical upper limit
  67. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  68. GRB 241207C: MASTER optical observations
  69. Fermi trigger No 755225799: Global MASTER-Net observations report
  70. Swift GRB 241128A: Global MASTER-Net observations report
  71. Swift GRB241127.91: Global MASTER-Net observations report
  72. GRB 241113A: Swift/UVOT Detection
  73. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  74. Fermi GRB 240918A: Global MASTER-Net observations report
  75. EP EP240913a: Global MASTER-Net observations report
  76. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  77. LIGO/Virgo/KAGRA S240830gn: Updated Sky localization and EM Bright Classification
  78. GRB 240829A: Swift-BAT refined analysis
  79. LAT GRB240828.62: Global MASTER-Net observations report
  80. Fermi trigger No 745866488: Global MASTER-Net observations report
  81. Fermi trigger No 745057312: Global MASTER-Net observations report
  82. Swift GRB 240811A: Global MASTER-Net observations report
  83. GRB 240727C: AstroSat CZTI detection of a long burst
  84. Konus-Wind detection of GRB 240627A
  85. Fermi GRB 240702A: Global MASTER-Net observations report
  86. Fermi trigger No 741211696: Global MASTER-Net observations report
  87. Swift Trigger 1232465: consistent with noise
  88. Konus-Wind detection of GRB 240529A
  89. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  90. GRB 240419B: Swift-BAT refined analysis
  91. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  92. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  93. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  94. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  95. Swift GRB 240419B: Global MASTER-Net observations report
  96. GRB 240414A: Swift-BAT refined analysis
  97. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  98. Fermi GRB 240408A: Global MASTER-Net observations report
  99. Konus-Wind detection of LXT 240402A/GRB 240402B
  100. Konus-Wind detection of GRB 240303B

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