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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

29096 results found.

  1. GRB 260818B: EP-FXT follow-up observation
  2. GRB 260818A: J-band observations with WINTER
  3. GRB 260818B: SVOM/ECLAIRs refined analysis
  4. GRB 260818A: SVOM/ECLAIRs refined analysis
  5. GRB 260818B: NOT optical upper limits
  6. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  7. GRB260818A: EP-FXT follow-up observation
  8. GRB 260818B: LCO optical upper limits
  9. GRB 260818B: SVOM detection of a short burst
  10. SVOM trigger sb26081806 is not a GRB
  11. EP260806a: SAO RAS multicolor optical observations
  12. GRB 260818A: LCO optical upper limits
  13. EP260812a: AbAO optical upper limit
  14. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  15. GRB 260818A: SVOM possible detection of a long and faint GRB
  16. EP260806a: SVOM/ECLAIRs detection through targeted search
  17. The EP-WXT trigger 01709281429 is likely a flaring star
  18. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  19. EP260806a: WFST optical observations
  20. The EP-WXT trigger 01709280562 is likely a flaring star
  21. The EP-WXT trigger 01709279838 is likely a flaring star
  22. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  23. GRB 260808B: Liverpool Telescope further optical observations
  24. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  25. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  26. GRB 260813A: Fermi GBM Final Real-time Localization
  27. EP260812a: NOT and Liverpool Telescope upper limits:
  28. EP260812a: SVOM/C-GFT optical upper limit
  29. EP260812b: COLIBRÍ optical observations
  30. EP260812b: SVOM/VT optical observation
  31. GRB 260808A: SVOM/GRM observation
  32. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  33. Fermi GBM Sub-Threshold Detection of GRB 260809A
  34. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  35. GRB 260808B: SVOM/VT optical re-brightening at day 3
  36. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  37. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  38. GRB 260808A: GECAM-B observation
  39. GRB 260807A: SVOM/ECLAIRs refined analysis
  40. GRB260808B: MAO/AZT-22 optical observations
  41. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  42. GRB 260809A: J-band upper limit with WINTER
  43. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  44. GRB 260806A: Glowbug gamma-ray detection
  45. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  46. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  47. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  48. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  49. The EP-WXT trigger 01709278015 is likely a flaring star
  50. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  51. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  52. GRB 260809A: NOT optical observations
  53. GRB260809A: MAO/AZT-22 optical observations
  54. GRB260809A: OHP/T193 optical observations
  55. GRB 260809A: SVOM/VT optical counterpart
  56. EP260809a: J-band upper limit with WINTER
  57. GRB 260808B: J-band upper limit with WINTER
  58. GRB 260808B: SVOM/ECLAIRs refined analysis
  59. GRB 260809A: SVOM detection of a faint burst
  60. GRB 260808B: Liverpool Telescope optical observations
  61. GRB 260808B: NOT optical observations
  62. GRB 260808B: LCO optical observations
  63. GRB 260808A: NuSTAR detection of prompt emission
  64. EP260809a: COLIBRÍ optical observations
  65. EP260809a: LCO optical observation
  66. EP260809a: OHP/T193 optical observations
  67. GRB260808B: OHP/T193 optical observations
  68. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  69. GRB 260808B: SVOM/VT optical afterglow confirmation
  70. GRB 260808C: Fermi GBM Final Real-time Localization
  71. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  72. GRB 260808B: SVOM/VT optical candidate from VHF data
  73. GRB 260808B: SVOM detection of a faint burst
  74. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  75. Fermi GRB 260808A: Global MASTER-Net observations report
  76. GRB 260808A: Fermi GBM Final Real-time Localization
  77. IceCube Alert 260807A: Global MASTER-Net observations report
  78. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  79. GRB 260807A: SVOM possible detection of a faint burst
  80. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  81. EP260806a: COLIBRÍ optical observations
  82. EP260806a: SVOM/VT optical observation
  83. EP260806a: OSIRIS+/GTC redshift z=0.089
  84. EP260806a: LCO likely optical counterpart
  85. GRB 260715A: cubesat Avion detection
  86. GRB 260709A: cubesat Avion detection
  87. GRB 260708A: cubesat Avion detection
  88. SN 2026stf / GRB 260708A: ATLAS forced photometry
  89. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  90. GRB 260805B: Glowbug gamma-ray detection
  91. Fermi GRB 260805A: Global MASTER-Net observations report
  92. GRB 260805B: Fermi GBM Final Localization
  93. GRB 260804A: Glowbug gamma-ray detection
  94. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  95. GRB 260805A: Fermi GBM Final Localization
  96. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  97. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  98. GRB 260804A: Fermi GBM Final Real-time Localization
  99. GRB 260708A: LCO further optical observations show supernova features
  100. GRB 260803A: Fermi GBM Final Real-time Localization

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