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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"

26484 results found.

  1. GRB 260914A: SVOM/ECLAIRs refined analysis
  2. GRB 260909A: Swift-XRT observations
  3. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  4. GRB 260915A: SVOM/C-GFT optical upper limits
  5. GRB 260915A: EP-FXT follow-up observation
  6. GRB 260915A: SVOM/VT refined early optical upper limits
  7. GRB 260915A: REM optical/NIR observations
  8. GRB 260914A: REM optical/NIR observations
  9. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  10. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  11. GRB 260915A: NOT optical upper limit
  12. GRB 260915A: SVOM/VT optical upper limits from VHF data
  13. GRB 260915A: LCO optical upper limits
  14. GRB 260914A: EP-FXT follow-up observation
  15. GRB 260915A: SVOM detection of a burst
  16. GRB 260914A: LCO optical observation
  17. GRB 260914A: SVOM/C-GFT optical observations
  18. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  19. GRB 260914A: SVOM detection of a burst
  20. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  21. GRB 260818A: Continued ATCA observations
  22. GRB 260913A: SVOM/C-GFT optical upper limit
  23. GRB 260913A: SVOM detection of a faint burst
  24. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  25. GRB 260907A: SVOM/GRM observation
  26. GRB 260909A: CrAO and AbAO optical upper limits
  27. GRB 260909A: SVOM/ECLAIRs refined analysis
  28. GRB 260910B: GOTO tentative optical counterpart candidates
  29. GRB 260909A: KAIT optical upper limit
  30. GRB 260903A: Swift-XRT observations
  31. GRB 260909A: OHP/T193 z-band upper limit
  32. GRB 260909A: VLT optical and near-infrared upper limits
  33. GRB 260909A: EP-FXT follow-up observation
  34. EP260806a: NOEMA detection
  35. EP260623a: NOEMA detections
  36. GRB 260909A: SVOM/GRM observation
  37. GRB 260909A: Mondy optical observations and afterglow candidate
  38. GRB 260909A: Xinglong 2.16m optical upper limit
  39. GRB 260909A: SVOM/C-GFT optical upper limit
  40. GRB 260909A: SVOM detection of a burst
  41. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  42. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  43. GRB 260903A: SAO RAS optical upper limit
  44. The EP-WXT trigger 01709305715 is likely a flaring star
  45. EP260903a: EP-FXT follow-up observation
  46. The EP-WXT trigger 01709302592 is likely a flaring star
  47. GRB 260903A: J-band upper limit with WINTER
  48. GRB 260903A: SVOM/ECLAIRs refined analysis
  49. GRB260903A: Liverpool Telescope optical observations
  50. GRB 260903A: SAO RAS optical observations
  51. GRB 260830A: GECAM-B detection of a burst
  52. EP260903a: EP-WXT detection of a fast X-ray transient
  53. GRB 260903A: EP-FXT follow-up observation
  54. GRB 260903A: OHP/T193 optical afterglow detection
  55. NuSTAR Transient 260828: SOAR Optical Upper Limits
  56. GRB 260903A: SVOM/VT optical candidate
  57. GRB 260903A: Retraction of optical counterpart of GCN 45501
  58. GRB 260831A: GECAM-B observation
  59. GRB 260903A: LCO optical counterpart detection
  60. GRB 260903A: SVOM detection of a soft faint burst
  61. EP260901a: SVOM/VT optical upper limits
  62. EP260901a: EP-FXT follow-up observation
  63. Konus-Wind detection of GRB 260829A
  64. GRB 260829A: SVOM/GRM observation
  65. GRB 260818A: ATCA detection of a candidate radio counterpart
  66. EP260830a: EP-FXT follow-up observation
  67. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  68. NuSTAR Transient 260828: LCO Optical Upper Limits
  69. EP260901a: EP-WXT detection of a fast X-ray transient
  70. GRB 260829A: AstroSat CZTI detection
  71. GRB 260831B: EP-FXT follow-up observation
  72. GRB 260831B: LCO optical upper limits
  73. EP260830a: EP-WXT detection of a fast X-ray transient
  74. GRB 260827A: SVOM/GRM observation
  75. NuSTAR 260828: a 1100s hard X-ray transient
  76. GRB 260831B: SVOM detection of a possible burst
  77. GRB 260827A: Glowbug gamma-ray detection
  78. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  79. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  80. GRB 260829A: GECAM-B observation of a long burst
  81. GRB 260825A: SVOM/GRM observation of a long burst
  82. GRB 260829A: Fermi GBM Detection
  83. GRB 260825A: AstroSat CZTI detection
  84. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  85. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  86. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  87. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  88. GRB 260818B: Further EP-FXT observation
  89. GRB 260818B: VLT optical and nIR observations
  90. GRB 260818B: TNG NIR observations
  91. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  92. GRB 260818B: 6 GHz VLA observations
  93. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  94. GRB 260808B: SAO RAS observations of the optical rebrightening
  95. EP Alert 260820.31: Global MASTER-Net observations report
  96. GRB 260807A: EP-FXT follow-up observations
  97. GRB 260822A: SVOM/ECLAIRs refined analysis
  98. GRB 260809A: SVOM/ECLAIRs refined analysis
  99. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  100. GRB 260822A: PRIME near-infrared upper limits from multiple epochs

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