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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"

28036 results found.

  1. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  2. GRB 260917A: Glowbug gamma-ray detection
  3. GRB 260915A: SVOM/ECLAIRs refined analysis
  4. GRB 260917B: WINTER J-band observations
  5. GRB 260917B: SVOM/VT optical observations
  6. SVOM GRB260917.16: Global MASTER-Net observations report
  7. GRB 260917B: LCO optical observation
  8. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  9. GRB 260917B: SVOM detection of a faint burst
  10. GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
  11. Fermi trigger No 811304653: Global MASTER-Net observations report
  12. GRB 260915A: J-band upper limit with WINTER
  13. Fermi trigger No 811264269: Global MASTER-Net observations report
  14. GRB 260909A: NOEMA detection
  15. GRB 260914A: Mondy and TShAO optical observations
  16. GRB 260914A: SVOM/ECLAIRs refined analysis
  17. GRB 260909A: Swift-XRT observations
  18. GRB 260916A: MAXI/GSC detection
  19. MAXI GRB260916.37: Global MASTER-Net observations report
  20. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  21. GRB 260915A: SVOM/C-GFT optical upper limits
  22. GRB 260915A: EP-FXT follow-up observation
  23. GRB 260915A: SVOM/VT refined early optical upper limits
  24. GRB 260915A: REM optical/NIR observations
  25. GRB 260914A: REM optical/NIR observations
  26. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  27. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  28. GRB 260915A: NOT optical upper limit
  29. SVOM GRB260915.05: Global MASTER-Net observations report
  30. GRB 260915A: SVOM/VT optical upper limits from VHF data
  31. Fermi GBM Sub-Threshold Detection of GRB 260915A
  32. GRB 260915A: LCO optical upper limits
  33. EP Alert 260914.53: Global MASTER-Net observations report
  34. GRB 260914A: EP-FXT follow-up observation
  35. GRB 260915A: SVOM detection of a burst
  36. Fermi GBM Sub-Threshold Detection of GRB 260914A
  37. GRB 260914A: LCO optical observation
  38. GRB 260914A: SVOM/C-GFT optical observations
  39. GRB 260914A: SVOM/VT optical observation from VHF data
  40. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  41. SVOM GRB260914.47: Global MASTER-Net observations report
  42. GRB 260914A: SVOM detection of a burst
  43. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  44. GRB 260818A: Continued ATCA observations
  45. SVOM GRB260913.32: Global MASTER-Net observations report
  46. GRB 260913A: SVOM/C-GFT optical upper limit
  47. GRB 260913A: SVOM detection of a faint burst
  48. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  49. GRB 260907A: SVOM/GRM observation
  50. GRB 260909A: CrAO and AbAO optical upper limits
  51. GRB 260909A: KAIT optical upper limit
  52. GRB 260903A: Swift-XRT observations
  53. GRB 260909A: OHP/T193 z-band upper limit
  54. GRB 260909A: VLT optical and near-infrared upper limits
  55. EP Alert 260909.53: Global MASTER-Net observations report
  56. GRB 260909A: EP-FXT follow-up observation
  57. EP260806a: NOEMA detection
  58. EP260623a: NOEMA detections
  59. GRB 260909A: Mondy optical observations and afterglow candidate
  60. GRB 260909A: Xinglong 2.16m optical upper limit
  61. GRB 260909A: SVOM/C-GFT optical upper limit
  62. GRB 260909A: SVOM detection of a burst
  63. Fermi trigger No 810554827: Global MASTER-Net observations report
  64. EP Alert 260908.60: Global MASTER-Net observations report
  65. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  66. Fermi GRB 260907B: Global MASTER-Net observations report
  67. GRB 260903A: SAO RAS optical upper limit
  68. Fermi GRB 260907A: Global MASTER-Net observations report
  69. EP260903a: EP-FXT follow-up observation
  70. EP Alert 260905.11: Global MASTER-Net observations report
  71. GRB 260903A: J-band upper limit with WINTER
  72. EP Alert 260903.47: Global MASTER-Net observations report
  73. GRB260903A: Liverpool Telescope optical observations
  74. GRB 260903A: SAO RAS optical observations
  75. GRB 260830A: GECAM-B detection of a burst
  76. EP260903a: EP-WXT detection of a fast X-ray transient
  77. EP Alert 260903.62: Global MASTER-Net observations report
  78. GRB 260830A: Insight-HXMT/HE detection
  79. GRB 260903A: EP-FXT follow-up observation
  80. GRB 260903A: OHP/T193 optical afterglow detection
  81. NuSTAR Transient 260828: SOAR Optical Upper Limits
  82. SVOM GRB260903A: Global MASTER-Net observations report
  83. GRB 260903A: LCO optical counterpart detection
  84. GRB 260827A: Insight-HXMT/HE detection
  85. EP260901a: SVOM/VT optical upper limits
  86. EP260901a: EP-FXT follow-up observation
  87. GRB 260829A: SVOM/GRM observation
  88. GRB 260818A: ATCA detection of a candidate radio counterpart
  89. EP260830a: EP-FXT follow-up observation
  90. EP260901a: Global MASTER-Net observations report
  91. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  92. NuSTAR Transient 260828: LCO Optical Upper Limits
  93. EP260901a: EP-WXT detection of a fast X-ray transient
  94. GRB 260830A: NuSTAR detection of prompt emission
  95. GRB 260831B: LCO optical upper limits
  96. EP260830a: Global MASTER-Net observations report
  97. EP260830a: EP-WXT detection of a fast X-ray transient
  98. GRB 260827A: SVOM/GRM observation
  99. NuSTAR 260828: a 1100s hard X-ray transient
  100. GRB 260831B: SVOM detection of a possible burst

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