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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"

19426 results found.

  1. GRB 260903A: OHP/T193 optical afterglow detection
  2. NuSTAR Transient 260828: SOAR Optical Upper Limits
  3. GRB 260903A: LCO optical counterpart detection
  4. GRB 260903A: SVOM detection of a soft faint burst
  5. EP260901a: SVOM/VT optical upper limits
  6. GRB 260829A: SVOM/GRM observation
  7. GRB 260818A: ATCA detection of a candidate radio counterpart
  8. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  9. NuSTAR Transient 260828: LCO Optical Upper Limits
  10. EP260901a: EP-WXT detection of a fast X-ray transient
  11. GRB 260831B: LCO optical upper limits
  12. EP260830a: EP-WXT detection of a fast X-ray transient
  13. GRB 260827A: SVOM/GRM observation
  14. GRB 260831B: SVOM detection of a possible burst
  15. EP260727a: ATCA 10 GHz detection
  16. GRB 260825A: SVOM/GRM observation of a long burst
  17. GRB 260818B: Further EP-FXT observation
  18. GRB 260818B: VLT optical and nIR observations
  19. GRB 260818B: TNG NIR observations
  20. GRB 260818B: 6 GHz VLA observations
  21. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  22. GRB 260808B: SAO RAS observations of the optical rebrightening
  23. EP Alert 260820.31: Global MASTER-Net observations report
  24. GRB 260822A: SVOM/ECLAIRs refined analysis
  25. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  26. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  27. EP260822a: EP-FXT non-detection and upper limit
  28. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  29. EP260822a: Einstein Probe detection of a fast X-ray transient
  30. GRB 260822A: LCO optical upper limits
  31. GRB 260822A: GROWTH-India Telescope Upper Limits
  32. GRB 260822A: SVOM detection of a short burst
  33. GRB 260818B: SVOM/C-GFT optical upper limit
  34. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  35. EP detected a brightening of LMXB 1ES 1735-26.9
  36. GRB 260818A: J-band observations with WINTER
  37. GRB 260818B: SVOM/ECLAIRs refined analysis
  38. GRB 260818A: SVOM/ECLAIRs refined analysis
  39. GRB 260818B: NOT optical upper limits
  40. GRB 260810A: SVOM/GRM observation
  41. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  42. GRB 260818B: LCO optical upper limits
  43. GRB 260818B: SVOM detection of a short burst
  44. EP260806a: SAO RAS multicolor optical observations
  45. GRB 260818A: LCO optical upper limits
  46. EP260812a: AbAO optical upper limit
  47. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  48. GRB 260818A: SVOM possible detection of a long and faint GRB
  49. EP260806a: NUTTELA-TAO optical observations
  50. EP260812a: AZT-22 optical upper limit
  51. EP260806a: WFST optical observations
  52. EP260812b: Optical upper limit with Kinder
  53. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  54. GRB 260808B: Liverpool Telescope further optical observations
  55. EP260812a: NOT and Liverpool Telescope upper limits:
  56. EP260812b: Liverpool Telescope observations
  57. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  58. EP260812a: SVOM/C-GFT optical upper limit
  59. EP260812b: COLIBRÍ optical observations
  60. EP260812b: SVOM/VT optical observation
  61. GRB 260808A: SVOM/GRM observation
  62. EP260812b: Einstein Probe detection of an X-ray transient
  63. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  64. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  65. EP260812a: Einstein Probe detection of an X-ray transient
  66. GRB 260809A: SAO RAS optical observations
  67. GRB 260808B: SAO RAS optical observations
  68. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  69. GRB 260807A: SVOM/ECLAIRs refined analysis
  70. EP260806a: MAO/AZT-22 optical observations
  71. GRB260808B: MAO/AZT-22 optical observations
  72. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  73. GRB 260809A: J-band upper limit with WINTER
  74. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  75. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  76. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  77. GRB 260809A: NOT optical observations
  78. GRB260809A: MAO/AZT-22 optical observations
  79. GRB260809A: OHP/T193 optical observations
  80. EP260809a: J-band upper limit with WINTER
  81. GRB 260808B: J-band upper limit with WINTER
  82. GRB 260808B: SVOM/ECLAIRs refined analysis
  83. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  84. GRB 260809A: SVOM detection of a faint burst
  85. GRB 260808B: Liverpool Telescope optical observations
  86. GRB 260808B: NOT optical observations
  87. GRB 260808B: LCO optical observations
  88. EP260809a: COLIBRÍ optical observations
  89. EP260809a: LCO optical observation
  90. EP260809a: OHP/T193 optical observations
  91. GRB260808B: OHP/T193 optical observations
  92. EP260809a: Einstein Probe detection of an X-ray transient
  93. GRB 260808B: SVOM/VT optical afterglow confirmation
  94. GRB 260808C: Fermi GBM Final Real-time Localization
  95. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  96. GRB 260808B: SVOM/VT optical candidate from VHF data
  97. GRB 260808B: SVOM detection of a faint burst
  98. GRB 260808A: Fermi GBM Final Real-time Localization
  99. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  100. GRB 260807A: SVOM possible detection of a faint burst

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