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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"

18250 results found.

  1. GRB 260917B: SVOM detection of a faint burst
  2. The EP-WXT trigger 01709317235 is likely a flaring star
  3. GRB 260915A: J-band upper limit with WINTER
  4. GRB 260909A: NOEMA detection
  5. GRB 260914A: Mondy and TShAO optical observations
  6. GRB 260909A: Swift-XRT observations
  7. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  8. GRB 260915A: SVOM/C-GFT optical upper limits
  9. GRB 260915A: EP-FXT follow-up observation
  10. GRB 260915A: REM optical/NIR observations
  11. GRB 260914A: REM optical/NIR observations
  12. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  13. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  14. GRB 260915A: NOT optical upper limit
  15. GRB 260915A: SVOM/VT optical upper limits from VHF data
  16. GRB 260915A: LCO optical upper limits
  17. GRB 260914A: EP-FXT follow-up observation
  18. GRB 260915A: SVOM detection of a burst
  19. GRB 260914A: LCO optical observation
  20. GRB 260914A: SVOM/C-GFT optical observations
  21. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  22. GRB 260914A: SVOM detection of a burst
  23. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  24. GRB 260913A: SVOM/C-GFT optical upper limit
  25. GRB 260913A: SVOM detection of a faint burst
  26. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  27. GRB 260907A: SVOM/GRM observation
  28. GRB 260909A: CrAO and AbAO optical upper limits
  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: Mondy optical observations and afterglow candidate
  37. GRB 260909A: Xinglong 2.16m optical upper limit
  38. GRB 260909A: SVOM/C-GFT optical upper limit
  39. GRB 260909A: SVOM detection of a burst
  40. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  41. GRB 260903A: SAO RAS optical upper limit
  42. The EP-WXT trigger 01709305715 is likely a flaring star
  43. EP260903a: EP-FXT follow-up observation
  44. The EP-WXT trigger 01709302592 is likely a flaring star
  45. GRB 260903A: J-band upper limit with WINTER
  46. GRB260903A: Liverpool Telescope optical observations
  47. GRB 260903A: SAO RAS optical observations
  48. EP260903a: EP-WXT detection of a fast X-ray transient
  49. GRB 260830A: Insight-HXMT/HE detection
  50. GRB 260903A: EP-FXT follow-up observation
  51. GRB 260903A: OHP/T193 optical afterglow detection
  52. NuSTAR Transient 260828: SOAR Optical Upper Limits
  53. GRB 260903A: LCO optical counterpart detection
  54. EP260901a: SVOM/VT optical upper limits
  55. EP260901a: EP-FXT follow-up observation
  56. GRB 260829A: SVOM/GRM observation
  57. GRB 260818A: ATCA detection of a candidate radio counterpart
  58. EP260830a: EP-FXT follow-up observation
  59. EP260901a: Global MASTER-Net observations report
  60. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  61. NuSTAR Transient 260828: LCO Optical Upper Limits
  62. EP260901a: EP-WXT detection of a fast X-ray transient
  63. GRB 260831B: EP-FXT follow-up observation
  64. GRB 260831B: LCO optical upper limits
  65. EP260830a: EP-WXT detection of a fast X-ray transient
  66. GRB 260827A: SVOM/GRM observation
  67. GRB 260831B: SVOM detection of a possible burst
  68. GRB 260825A: SVOM/GRM observation of a long burst
  69. GRB 260818B: Further EP-FXT observation
  70. GRB 260818B: VLT optical and nIR observations
  71. GRB 260818B: TNG NIR observations
  72. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  73. GRB 260818B: 6 GHz VLA observations
  74. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  75. GRB 260808B: SAO RAS observations of the optical rebrightening
  76. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  77. GRB 260822A: EP/FXT follow-up observations
  78. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  79. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  80. EP260822a: EP-FXT non-detection and upper limit
  81. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  82. EP260822a: Einstein Probe detection of a fast X-ray transient
  83. GRB 260822A: LCO optical upper limits
  84. The EP-WXT trigger 01709287395 is likely a flaring star
  85. GRB 260822A: GROWTH-India Telescope Upper Limits
  86. GRB 260818B: VLA radio observations
  87. GRB 260818B: SVOM/C-GFT optical upper limit
  88. The EP-WXT trigger 01709286204 is likely a flaring star
  89. EP detected a brightening of LMXB 1ES 1735-26.9
  90. GRB 260818B: EP-FXT follow-up observation
  91. GRB 260818A: J-band observations with WINTER
  92. GRB 260818B: NOT optical upper limits
  93. GRB 260810A: SVOM/GRM observation
  94. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  95. GRB260818A: EP-FXT follow-up observation
  96. GRB 260818B: LCO optical upper limits
  97. EP260806a: SAO RAS multicolor optical observations
  98. GRB 260818A: LCO optical upper limits
  99. EP260812a: AbAO optical upper limit
  100. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit

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