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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"

20358 results found.

  1. GRB 260914A: SVOM/C-GFT optical observations
  2. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  3. GRB 260914A: SVOM detection of a burst
  4. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  5. GRB 260913A: SVOM/C-GFT optical upper limit
  6. GRB 260913A: SVOM detection of a faint burst
  7. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  8. GRB 260907A: SVOM/GRM observation
  9. GRB 260909A: CrAO and AbAO optical upper limits
  10. GRB 260909A: SVOM/ECLAIRs refined analysis
  11. GRB 260909A: KAIT optical upper limit
  12. GRB 260903A: Swift-XRT observations
  13. GRB 260909A: OHP/T193 z-band upper limit
  14. GRB 260909A: VLT optical and near-infrared upper limits
  15. EP260806a: NOEMA detection
  16. EP260623a: NOEMA detections
  17. GRB 260909A: Mondy optical observations and afterglow candidate
  18. GRB 260909A: Xinglong 2.16m optical upper limit
  19. GRB 260909A: SVOM/C-GFT optical upper limit
  20. GRB 260909A: SVOM detection of a burst
  21. GRB 260903A: SAO RAS optical upper limit
  22. GRB 260903A: J-band upper limit with WINTER
  23. GRB 260903A: SVOM/ECLAIRs refined analysis
  24. GRB260903A: Liverpool Telescope optical observations
  25. GRB 260903A: SAO RAS optical observations
  26. EP260903a: EP-WXT detection of a fast X-ray transient
  27. GRB 260903A: OHP/T193 optical afterglow detection
  28. NuSTAR Transient 260828: SOAR Optical Upper Limits
  29. GRB 260831A: GECAM-B observation
  30. GRB 260903A: LCO optical counterpart detection
  31. EP260901a: SVOM/VT optical upper limits
  32. EP260901a: EP-FXT follow-up observation
  33. Konus-Wind detection of GRB 260829A
  34. GRB 260829A: SVOM/GRM observation
  35. GRB 260818A: ATCA detection of a candidate radio counterpart
  36. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  37. NuSTAR Transient 260828: LCO Optical Upper Limits
  38. EP260901a: EP-WXT detection of a fast X-ray transient
  39. GRB 260831B: LCO optical upper limits
  40. EP260830a: EP-WXT detection of a fast X-ray transient
  41. GRB 260827A: SVOM/GRM observation
  42. GRB 260831B: SVOM detection of a possible burst
  43. EP260727a: ATCA 10 GHz detection
  44. GRB 260825A: SVOM/GRM observation of a long burst
  45. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  46. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  47. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 260818B: Further EP-FXT observation
  49. GRB 260818B: VLT optical and nIR observations
  50. GRB 260818B: TNG NIR observations
  51. GRB 260818B: 6 GHz VLA observations
  52. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  53. GRB 260808B: SAO RAS observations of the optical rebrightening
  54. GRB 260822A: SVOM/ECLAIRs refined analysis
  55. GRB 260809A: SVOM/ECLAIRs refined analysis
  56. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  57. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  58. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  59. EP260822a: EP-FXT non-detection and upper limit
  60. GRB 260822A: GOTO optical counterpart detection
  61. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  62. EP260822a: Einstein Probe detection of a fast X-ray transient
  63. GRB 260822A: LCO optical upper limits
  64. GRB 260822A: GROWTH-India Telescope Upper Limits
  65. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  66. GRB 260818B: SVOM/C-GFT optical upper limit
  67. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  68. EP detected a brightening of LMXB 1ES 1735-26.9
  69. GRB 260818A: J-band observations with WINTER
  70. GRB 260818B: SVOM/ECLAIRs refined analysis
  71. GRB 260818A: SVOM/ECLAIRs refined analysis
  72. GRB 260818B: NOT optical upper limits
  73. GRB 260810A: SVOM/GRM observation
  74. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  75. GRB 260818B: LCO optical upper limits
  76. EP260806a: SAO RAS multicolor optical observations
  77. GRB 260818A: LCO optical upper limits
  78. EP260812a: AbAO optical upper limit
  79. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  80. EP260806a: SVOM/ECLAIRs detection through targeted search
  81. EP260806a: NUTTELA-TAO optical observations
  82. EP260812a: AZT-22 optical upper limit
  83. EP260806a: WFST optical observations
  84. EP260812b: Optical upper limit with Kinder
  85. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  86. GRB 260808B: Liverpool Telescope further optical observations
  87. EP260812a: NOT and Liverpool Telescope upper limits:
  88. EP260812b: Liverpool Telescope observations
  89. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  90. EP260812a: SVOM/C-GFT optical upper limit
  91. EP260812b: COLIBRÍ optical observations
  92. EP260812b: SVOM/VT optical observation
  93. GRB 260808A: SVOM/GRM observation
  94. EP260812b: Einstein Probe detection of an X-ray transient
  95. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  96. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  97. GRB 260810A: AstroSat CZTI detection of a long burst
  98. EP260812a: Einstein Probe detection of an X-ray transient
  99. GRB 260809A: SAO RAS optical observations
  100. GRB 260808B: SAO RAS optical observations

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