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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"

15983 results found.

  1. NuSTAR Transient 260828: SOAR Optical Upper Limits
  2. SVOM GRB260903A: Global MASTER-Net observations report
  3. GRB 260903A: LCO optical observations
  4. GRB 260903A: SVOM/VT optical candidate
  5. GRB 260903A: Retraction of optical counterpart of GCN 45501
  6. GRB 260903A: LCO optical counterpart detection
  7. GRB 260903A: SVOM detection of a soft faint burst
  8. EP260901a: SVOM/VT optical upper limits
  9. GRB 260829A: SVOM/GRM observation
  10. EP260901a: Global MASTER-Net observations report
  11. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  12. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  13. NuSTAR Transient 260828: LCO Optical Upper Limits
  14. GRB 260831B: LCO optical upper limits
  15. EP260830a: Global MASTER-Net observations report
  16. GRB 260827A: SVOM/GRM observation
  17. EP260727a: ATCA 10 GHz detection
  18. GRB 260825A: SVOM/GRM observation of a long burst
  19. GRB 260818B: Further EP-FXT observation
  20. GRB 260818B: VLT optical and nIR observations
  21. MAXI GRB260827.40: Global MASTER-Net observations report
  22. GRB 260818B: 6 GHz VLA observations
  23. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  24. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  25. GRB 260808B: SAO RAS observations of the optical rebrightening
  26. EP260822a: Global MASTER-Net observations report
  27. EP Alert 260820.31: Global MASTER-Net observations report
  28. GRB 260822A: SVOM/VT optical upper limits
  29. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  30. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  31. GRB 260822A: GOTO optical counterpart detection
  32. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  33. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  34. GRB 260822A: LCO optical upper limits
  35. GRB 260822A: GROWTH-India Telescope Upper Limits
  36. GRB 260822A: GOTO optical upper limit
  37. GRB 260818B: SVOM/C-GFT optical upper limit
  38. GRB 260818B: SVOM/GRM observation
  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. EP260806a: NUTTELA-TAO optical observations
  49. EP260812a: AZT-22 optical upper limit
  50. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  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. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  56. EP260812a: NOT and Liverpool Telescope upper limits:
  57. EP260812b: Liverpool Telescope observations
  58. EP260812b: GOTO detection of the optical counterpart
  59. EP260812a: SVOM/C-GFT optical upper limit
  60. EP260812b: COLIBRÍ optical observations
  61. EP260812b: SVOM/VT optical observation
  62. GRB 260808A: SVOM/GRM observation
  63. EP260812b: Einstein Probe detection of an X-ray transient
  64. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  65. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  66. GRB 260809A: SAO RAS optical observations
  67. GRB 260808B: SAO RAS optical observations
  68. GRB 260808B: SVOM/VT optical re-brightening at day 3
  69. EP260806a: MAO/AZT-22 optical observations
  70. GRB260808B: MAO/AZT-22 optical observations
  71. GRB 260809A: J-band upper limit with WINTER
  72. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  73. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  74. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  75. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  76. GRB 260809A: NOT optical observations
  77. GRB260809A: MAO/AZT-22 optical observations
  78. GRB260809A: OHP/T193 optical observations
  79. GRB 260809A: SVOM/VT optical counterpart
  80. EP260809a: J-band upper limit with WINTER
  81. GRB 260808B: J-band upper limit with WINTER
  82. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  83. GRB 260808B: Liverpool Telescope optical observations
  84. GRB 260808B: NOT optical observations
  85. GRB 260808B: LCO optical observations
  86. EP260809a: COLIBRÍ optical observations
  87. EP260809a: LCO optical observation
  88. EP260809a: OHP/T193 optical observations
  89. GRB260808B: OHP/T193 optical observations
  90. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  91. GRB 260808B: SVOM/VT optical afterglow confirmation
  92. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  93. GRB 260808B: SVOM/VT optical candidate from VHF data
  94. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  95. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  96. GRB 260807A: SVOM possible detection of a faint burst
  97. EP260806a: COLIBRÍ optical observations
  98. EP260806a: SVOM/VT optical observation
  99. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  100. EP260806a: OSIRIS+/GTC redshift z=0.089

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