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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"

3758 results found.

  1. Swift Trigger 1513439 is probably not a GRB
  2. GRB 260924A: GROWTH-India Telescope optical observations
  3. GRB 260924A: Swift detection of a burst
  4. GRB 260918A: SVOM/ECLAIRs refined analysis
  5. EP260920b: LCO optical counterpart detection
  6. EP Alert 260921.01: Global MASTER-Net observations report
  7. EP Alert 260920.66: Global MASTER-Net observations report
  8. EP260917b: EP-WXT detection of an X-ray transient
  9. IPN triangulation of GRB 260810A
  10. EP Alert 260917.32: Global MASTER-Net observations report
  11. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  12. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  13. GRB 260916A: MAXI/GSC detection
  14. EP Alert 260914.53: Global MASTER-Net observations report
  15. SVOM GRB260914.47: Global MASTER-Net observations report
  16. GRB 260907A: SVOM/GRM observation
  17. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  18. Fermi GRB 260907A: Global MASTER-Net observations report
  19. GRB 260907A: Fermi GBM Final Real-time Localization
  20. EP Alert 260903.62: Global MASTER-Net observations report
  21. SVOM GRB260903A: Global MASTER-Net observations report
  22. Konus-Wind detection of GRB 260829A
  23. GRB 260829A: SVOM/GRM observation
  24. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  25. NuSTAR 260828: a 1100s hard X-ray transient
  26. EP260727a: ATCA 10 GHz detection
  27. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  28. GRB 260818B: TNG NIR observations
  29. MAXI GRB260827.40: Global MASTER-Net observations report
  30. EP Alert 260820.31: Global MASTER-Net observations report
  31. IceCube Alert 260825A: Global MASTER-Net observations report
  32. GRB 260822A: GOTO optical counterpart detection
  33. GRB260822B: Fermi GBM Final Localization
  34. GRB 260818B: VLA radio observations
  35. EP260806a: SAO RAS multicolor optical observations
  36. EP260812a: SVOM/C-GFT optical upper limit
  37. GRB 260808B: SVOM/VT optical afterglow confirmation
  38. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  39. GRB 260808B: SVOM/VT optical candidate from VHF data
  40. EP260806a: Einstein Probe detection of an X-ray transient
  41. SN 2026stf / GRB 260708A: ATLAS forced photometry
  42. Fermi GRB 260805A: Global MASTER-Net observations report
  43. GRB 260803A: Fermi GBM Final Real-time Localization
  44. Fermi GRB 260802B: Global MASTER-Net observations report
  45. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  46. GRB260730A: Fermi GBM Final Localization
  47. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  48. GRB 260727A: AbAO and SAO RAS optical observations
  49. EP260728a: EP-FXT follow-up observation
  50. EP260727a: 1.5m OSN optical counterpart detection
  51. GRB 260726A: Liverpool Telescope optical observations
  52. GRB 260727A: Liverpool Telescope optical upper limits
  53. EP260727a: Liverpool Telescope confirmation of optical counterpart
  54. GRB 260728A: Fermi GBM Final Localization
  55. GRB 260726A: SVOM/VT optical candidate
  56. EP260723a: SVOM/VT optical observation
  57. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  58. Fermi GRB 260718A: Global MASTER-Net observations report
  59. GRB260708B: MAXI/GSC detection
  60. Fermi GBM Sub-Threshold Detection of GRB 260705A
  61. GRB 260705A: SVOM detection of a burst
  62. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  63. Fermi trigger No 804552016: Global MASTER-Net observations report
  64. Fermi GRB 260628A: Global MASTER-Net observations report
  65. GRB 260628A: Fermi GBM Final Real-time Localization
  66. Konus-Wind detection of GRB 260623B / EP260623a
  67. IPN triangulation of GRB 260605A
  68. GRB 260604A: 239Alferov CubeSat detection
  69. GRB 260506B: cubesat Avion detection
  70. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  71. GRB 260614A: AstroSat CZTI detection
  72. The EP-WXT trigger 01709269893 is likely a flaring star
  73. The EP-WXT trigger 01709269488 is likely a flaring star
  74. GRB 260610B / AT2026owq: SVOM/VT optical observations
  75. GRB 260515A: SOAR optical observations
  76. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  77. GRB 260604C: GOTO detections of the optical afterglow
  78. Fermi GRB 260604C: Global MASTER-Net observations report
  79. Fermi GRB 260604C: Global MASTER-Net observations report
  80. EP260602d: Optical Upper limits with kinder observations
  81. Fermi GRB 260602B: Global MASTER-Net observations report
  82. Fermi GRB 260602B: Global MASTER-Net observations report
  83. Fermi GRB 260601A: Global MASTER-Net observations report
  84. Fermi trigger No 801900520: Global MASTER-Net observations report
  85. GRB 260527A / EP260527a: VLA radio detection
  86. Fermi GRB 260529A: Global MASTER-Net observations report
  87. EP260527a: COLIBRÍ optical detection
  88. Fermi trigger No 801580882: Global MASTER-Net observations report
  89. Fermi GRB 260525A: Global MASTER-Net observations report
  90. GRB 260523B: AstroSat CZTI detection
  91. Fermi GRB 260522A: Global MASTER-Net observations report
  92. Fermi GRB 260516C: Global MASTER-Net observations report
  93. GRB 260516D: SVOM possible detection of a burst
  94. GRID detection of GRB 260507A
  95. SVOM GRB 260515A: Global MASTER-Net observations report
  96. Fermi GRB 260514A: Global MASTER-Net observations report
  97. Fermi GRB 260512A: Global MASTER-Net observations report
  98. GRB 260506A: Glowbug gamma-ray detection of a short burst
  99. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  100. Fermi GRB 260510A: Global MASTER-Net observations report

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