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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"

2256 results found.

  1. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  2. GRB 260915A: SVOM/VT optical upper limits
  3. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  4. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  5. GRB 260915A: NOT optical upper limit
  6. SVOM GRB260915.05: Global MASTER-Net observations report
  7. GRB 260915A: SVOM/VT optical upper limits from VHF data
  8. Fermi GBM Sub-Threshold Detection of GRB 260915A
  9. GRB 260915A: LCO optical upper limits
  10. EP Alert 260914.53: Global MASTER-Net observations report
  11. GRB 260914A: EP-FXT follow-up observation
  12. GRB 260915A: SVOM detection of a burst
  13. Fermi GBM Sub-Threshold Detection of GRB 260914A
  14. GRB 260914A: LCO optical observation
  15. GRB 260914A: SVOM/C-GFT optical observations
  16. GRB 260914A: SVOM/VT optical counterpart confirmation
  17. GRB 260914A: SVOM/VT optical observation from VHF data
  18. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  19. SVOM GRB260914.47: Global MASTER-Net observations report
  20. GRB 260914A: SVOM detection of a burst
  21. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  22. GRB 260818A: Continued ATCA observations
  23. SVOM GRB260913.32: Global MASTER-Net observations report
  24. GRB 260913A: SVOM/C-GFT optical upper limit
  25. GRB 260913A: SVOM detection of a faint burst
  26. GRB 260907A: SVOM/GRM observation
  27. GRB 260909A: CrAO and AbAO optical upper limits
  28. GRB 260909A: SVOM/ECLAIRs refined analysis
  29. GRB 260910B: GOTO tentative optical counterpart candidates
  30. GRB 260910B: Fermi GBM Final Real-time Localization
  31. EP260806a: VLA+ALMA radio detections
  32. GRB 260909A: OHP/T193 z-band upper limit
  33. GRB 260909A: VLT optical and near-infrared upper limits
  34. EP Alert 260909.53: Global MASTER-Net observations report
  35. GRB 260909A: EP-FXT follow-up observation
  36. GRB 260910A: Fermi GBM Final Real-time Localization
  37. EP260806a: NOEMA detection
  38. GRB 260909A: SVOM/VT optical upper limits
  39. GRB 260909A: SVOM/GRM observation
  40. GRB 260909A: Mondy optical observations and afterglow candidate
  41. GRB 260909A: Xinglong 2.16m optical upper limit
  42. GRB 260909A: SVOM/C-GFT optical upper limit
  43. GRB 260909A: SVOM detection of a burst
  44. Fermi trigger No 810554827: Global MASTER-Net observations report
  45. EP Alert 260908.60: Global MASTER-Net observations report
  46. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  47. Fermi GRB 260907B: Global MASTER-Net observations report
  48. GRB 260903A: SAO RAS optical upper limit
  49. The EP-WXT trigger 01709305715 is likely a flaring star
  50. GRB 260907B: Fermi GBM Final Real-time Localization
  51. Fermi GRB 260907A: Global MASTER-Net observations report
  52. GRB 260907A: Fermi GBM Final Real-time Localization
  53. EP260903a: EP-FXT follow-up observation
  54. EP Alert 260905.11: Global MASTER-Net observations report
  55. The EP-WXT trigger 01709302592 is likely a flaring star
  56. GRB 260903A: J-band upper limit with WINTER
  57. EP Alert 260903.47: Global MASTER-Net observations report
  58. GRB 260903A: SVOM/ECLAIRs refined analysis
  59. GRB260903A: Liverpool Telescope optical observations
  60. GRB 260903A: SAO RAS optical observations
  61. GRB 260830A: GECAM-B detection of a burst
  62. EP260903a: EP-WXT detection of a fast X-ray transient
  63. EP Alert 260903.62: Global MASTER-Net observations report
  64. GRB 260830A: Insight-HXMT/HE detection
  65. GRB 260903A: EP-FXT follow-up observation
  66. GRB 260903A: NOT optical observations and afterglow fading
  67. NuSTAR Transient 260828: SOAR Optical Upper Limits
  68. SVOM GRB260903A: Global MASTER-Net observations report
  69. GRB 260903A: SVOM/VT optical candidate
  70. GRB 260831A: GECAM-B observation
  71. GRB 260903A: LCO optical counterpart detection
  72. GRB 260827A: Insight-HXMT/HE detection
  73. GRB 260903A: SVOM detection of a soft faint burst
  74. EP260901a: SVOM/VT optical upper limits
  75. EP260901a: EP-FXT follow-up observation
  76. GRB 260829A: SVOM/GRM observation
  77. GRB 260818A: ATCA detection of a candidate radio counterpart
  78. EP260830a: EP-FXT follow-up observation
  79. EP260901a: Global MASTER-Net observations report
  80. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  81. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  82. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  83. NuSTAR Transient 260828: LCO Optical Upper Limits
  84. EP260901a: EP-WXT detection of a fast X-ray transient
  85. SVOM trigger sb26083106 is not a GRB
  86. GRB 260829A: AstroSat CZTI detection
  87. GRB 260831B: EP-FXT follow-up observation
  88. GRB 260830A: NuSTAR detection of prompt emission
  89. GRB 260831B: LCO optical upper limits
  90. EP260830a: Global MASTER-Net observations report
  91. EP260830a: EP-WXT detection of a fast X-ray transient
  92. GRB 260827A: SVOM/GRM observation
  93. NuSTAR 260828: a 1100s hard X-ray transient
  94. GRB 260831B: SVOM detection of a possible burst
  95. GRB 260827A: Glowbug gamma-ray detection
  96. EP260727a: ATCA 10 GHz detection
  97. GRB 260831A: Fermi GBM Final Real-time Localization
  98. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  99. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  100. GRB 260829A: GECAM-B observation of a long burst

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