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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"

27925 results found.

  1. GRB 260915A: J-band upper limit with WINTER
  2. Fermi trigger No 811264269: Global MASTER-Net observations report
  3. GRB 260909A: NOEMA detection
  4. GRB 260914A: Mondy and TShAO optical observations
  5. GRB 260914A: SVOM/ECLAIRs refined analysis
  6. GRB 260909A: Swift-XRT observations
  7. GRB 260916A: MAXI/GSC detection
  8. MAXI GRB260916.37: Global MASTER-Net observations report
  9. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  10. GRB 260915A: SVOM/C-GFT optical upper limits
  11. GRB 260915A: EP-FXT follow-up observation
  12. GRB 260915A: SVOM/VT refined early optical upper limits
  13. GRB 260915A: REM optical/NIR observations
  14. GRB 260914A: REM optical/NIR observations
  15. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  16. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  17. GRB 260915A: NOT optical upper limit
  18. SVOM GRB260915.05: Global MASTER-Net observations report
  19. GRB 260915A: SVOM/VT optical upper limits from VHF data
  20. Fermi GBM Sub-Threshold Detection of GRB 260915A
  21. GRB 260915A: LCO optical upper limits
  22. EP Alert 260914.53: Global MASTER-Net observations report
  23. GRB 260914A: EP-FXT follow-up observation
  24. GRB 260915A: SVOM detection of a burst
  25. Fermi GBM Sub-Threshold Detection of GRB 260914A
  26. GRB 260914A: LCO optical observation
  27. GRB 260914A: SVOM/C-GFT optical observations
  28. GRB 260914A: SVOM/VT optical observation from VHF data
  29. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  30. SVOM GRB260914.47: Global MASTER-Net observations report
  31. GRB 260914A: SVOM detection of a burst
  32. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  33. GRB 260818A: Continued ATCA observations
  34. SVOM GRB260913.32: Global MASTER-Net observations report
  35. GRB 260913A: SVOM/C-GFT optical upper limit
  36. GRB 260913A: SVOM detection of a faint burst
  37. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  38. GRB 260907A: SVOM/GRM observation
  39. GRB 260909A: CrAO and AbAO optical upper limits
  40. GRB 260909A: KAIT optical upper limit
  41. GRB 260903A: Swift-XRT observations
  42. GRB 260909A: OHP/T193 z-band upper limit
  43. GRB 260909A: VLT optical and near-infrared upper limits
  44. EP Alert 260909.53: Global MASTER-Net observations report
  45. GRB 260909A: EP-FXT follow-up observation
  46. EP260806a: NOEMA detection
  47. EP260623a: NOEMA detections
  48. GRB 260909A: Mondy optical observations and afterglow candidate
  49. GRB 260909A: Xinglong 2.16m optical upper limit
  50. GRB 260909A: SVOM/C-GFT optical upper limit
  51. GRB 260909A: SVOM detection of a burst
  52. Fermi trigger No 810554827: Global MASTER-Net observations report
  53. EP Alert 260908.60: Global MASTER-Net observations report
  54. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  55. Fermi GRB 260907B: Global MASTER-Net observations report
  56. GRB 260903A: SAO RAS optical upper limit
  57. Fermi GRB 260907A: Global MASTER-Net observations report
  58. EP260903a: EP-FXT follow-up observation
  59. EP Alert 260905.11: Global MASTER-Net observations report
  60. GRB 260903A: J-band upper limit with WINTER
  61. EP Alert 260903.47: Global MASTER-Net observations report
  62. GRB260903A: Liverpool Telescope optical observations
  63. GRB 260903A: SAO RAS optical observations
  64. GRB 260830A: GECAM-B detection of a burst
  65. EP260903a: EP-WXT detection of a fast X-ray transient
  66. EP Alert 260903.62: Global MASTER-Net observations report
  67. GRB 260830A: Insight-HXMT/HE detection
  68. GRB 260903A: EP-FXT follow-up observation
  69. GRB 260903A: OHP/T193 optical afterglow detection
  70. NuSTAR Transient 260828: SOAR Optical Upper Limits
  71. SVOM GRB260903A: Global MASTER-Net observations report
  72. GRB 260903A: LCO optical counterpart detection
  73. GRB 260827A: Insight-HXMT/HE detection
  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. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  81. NuSTAR Transient 260828: LCO Optical Upper Limits
  82. EP260901a: EP-WXT detection of a fast X-ray transient
  83. GRB 260830A: NuSTAR detection of prompt emission
  84. GRB 260831B: LCO optical upper limits
  85. EP260830a: Global MASTER-Net observations report
  86. EP260830a: EP-WXT detection of a fast X-ray transient
  87. GRB 260827A: SVOM/GRM observation
  88. NuSTAR 260828: a 1100s hard X-ray transient
  89. GRB 260831B: SVOM detection of a possible burst
  90. GRB 260827A: Glowbug gamma-ray detection
  91. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  92. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  93. GRB 260825A: SVOM/GRM observation of a long burst
  94. GRB 260829A: Fermi GBM Detection
  95. GRB 260825A: AstroSat CZTI detection
  96. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  97. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  98. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  99. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  100. GRB 260818B: Further EP-FXT observation

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