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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"
  1. GRB 260915A: EP-FXT follow-up observation
  2. GRB 260915A: REM optical/NIR observations
  3. GRB 260914A: REM optical/NIR observations
  4. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  5. GRB 260915A: SVOM/VT optical upper limits
  6. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  7. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  8. GRB 260915A: 10.4m GTC deep optical limits
  9. GRB 260915A: NOT optical upper limit
  10. SVOM GRB260915.05: Global MASTER-Net observations report
  11. GRB 260915A: SVOM/VT optical upper limits from VHF data
  12. Fermi GBM Sub-Threshold Detection of GRB 260915A
  13. GRB 260915A: LCO optical upper limits
  14. EP Alert 260914.53: Global MASTER-Net observations report
  15. GRB 260914A: EP-FXT follow-up observation
  16. GRB 260915A: SVOM detection of a burst
  17. Fermi GBM Sub-Threshold Detection of GRB 260914A
  18. GRB 260914A: LCO optical observation
  19. GRB 260914A: SVOM/C-GFT optical observations
  20. GRB 260914A: SVOM/VT optical counterpart confirmation
  21. GRB 260914A: SVOM/VT optical observation from VHF data
  22. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  23. SVOM GRB260914.47: Global MASTER-Net observations report
  24. GRB 260914A: SVOM detection of a burst
  25. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  26. GRB 260818A: Continued ATCA observations
  27. SVOM GRB260913.32: Global MASTER-Net observations report
  28. GRB 260913A: SVOM/C-GFT optical upper limit
  29. GRB 260913A: SVOM detection of a faint burst
  30. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  31. GRB 260907A: SVOM/GRM observation
  32. GRB 260909A: CrAO and AbAO optical upper limits
  33. GRB 260909A: SVOM/ECLAIRs refined analysis
  34. GRB 260910B: GOTO tentative optical counterpart candidates
  35. GRB 260909A: Swift ToO observations
  36. GRB 260910B: Fermi GBM Final Real-time Localization
  37. GRB 260909A: KAIT optical upper limit
  38. GRB 260903A: Swift-XRT observations
  39. EP260806a: VLA+ALMA radio detections
  40. GRB 260909A: OHP/T193 z-band upper limit
  41. GRB 260909A: VLT optical and near-infrared upper limits
  42. EP Alert 260909.53: Global MASTER-Net observations report
  43. GRB 260909A: EP-FXT follow-up observation
  44. GRB 260910A: Fermi GBM Final Real-time Localization
  45. EP260806a: NOEMA detection
  46. EP260623a: NOEMA detections
  47. GRB 260909A: SVOM/VT optical upper limits
  48. GRB 260909A: SVOM/GRM observation
  49. GRB 260909A: Mondy optical observations and afterglow candidate
  50. GRB 260909A: Xinglong 2.16m optical upper limit
  51. GRB 260909A: SVOM/C-GFT optical upper limit
  52. GRB 260909A: SVOM detection of a burst
  53. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  54. Fermi trigger No 810554827: Global MASTER-Net observations report
  55. EP Alert 260908.60: Global MASTER-Net observations report
  56. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  57. GRB 260903A: Swift ToO observations
  58. Fermi GRB 260907B: Global MASTER-Net observations report
  59. GRB 260903A: SAO RAS optical upper limit
  60. The EP-WXT trigger 01709305715 is likely a flaring star
  61. GRB 260907B: Fermi GBM Final Real-time Localization
  62. Fermi GRB 260907A: Global MASTER-Net observations report
  63. GRB 260907A: Fermi GBM Final Real-time Localization
  64. EP260903a: EP-FXT follow-up observation
  65. EP Alert 260905.11: Global MASTER-Net observations report
  66. The EP-WXT trigger 01709302592 is likely a flaring star
  67. GRB 260903A: J-band upper limit with WINTER
  68. EP Alert 260903.47: Global MASTER-Net observations report
  69. GRB 260903A: SVOM/ECLAIRs refined analysis
  70. GRB260903A: Liverpool Telescope optical observations
  71. GRB 260903A: SAO RAS optical observations
  72. GRB 260830A: GECAM-B detection of a burst
  73. EP260903a: EP-WXT detection of a fast X-ray transient
  74. EP Alert 260903.62: Global MASTER-Net observations report
  75. GRB 260830A: Insight-HXMT/HE detection
  76. GRB 260903A: EP-FXT follow-up observation
  77. GRB 260903A: OHP/T193 optical afterglow detection
  78. GRB 260903A: NOT optical observations and afterglow fading
  79. NuSTAR Transient 260828: SOAR Optical Upper Limits
  80. SVOM GRB260903A: Global MASTER-Net observations report
  81. GRB 260903A: LCO optical observations
  82. GRB 260903A: SVOM/VT optical candidate
  83. GRB 260903A: Retraction of optical counterpart of GCN 45501
  84. GRB 260831A: GECAM-B observation
  85. GRB 260903A: LCO optical counterpart detection
  86. GRB 260827A: Insight-HXMT/HE detection
  87. GRB 260903A: SVOM detection of a soft faint burst
  88. EP260901a: SVOM/VT optical upper limits
  89. EP260901a: EP-FXT follow-up observation
  90. Konus-Wind detection of GRB 260829A
  91. GRB 260829A: SVOM/GRM observation
  92. GRB 260818A: ATCA detection of a candidate radio counterpart
  93. EP260830a: EP-FXT follow-up observation
  94. EP260901a: Global MASTER-Net observations report
  95. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  96. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  97. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  98. NuSTAR Transient 260828: LCO Optical Upper Limits
  99. EP260901a: EP-WXT detection of a fast X-ray transient
  100. SVOM trigger sb26083106 is not a GRB

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