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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"

18241 results found.

  1. GRB 260915A: REM optical/NIR observations
  2. GRB 260914A: REM optical/NIR observations
  3. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  4. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  5. GRB 260915A: NOT optical upper limit
  6. GRB 260915A: SVOM/VT optical upper limits from VHF data
  7. GRB 260915A: LCO optical upper limits
  8. GRB 260914A: EP-FXT follow-up observation
  9. GRB 260915A: SVOM detection of a burst
  10. GRB 260914A: LCO optical observation
  11. GRB 260914A: SVOM/C-GFT optical observations
  12. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  13. GRB 260914A: SVOM detection of a burst
  14. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  15. GRB 260913A: SVOM/C-GFT optical upper limit
  16. GRB 260913A: SVOM detection of a faint burst
  17. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  18. GRB 260907A: SVOM/GRM observation
  19. GRB 260909A: CrAO and AbAO optical upper limits
  20. GRB 260909A: KAIT optical upper limit
  21. GRB 260903A: Swift-XRT observations
  22. GRB 260909A: OHP/T193 z-band upper limit
  23. GRB 260909A: VLT optical and near-infrared upper limits
  24. GRB 260909A: EP-FXT follow-up observation
  25. EP260806a: NOEMA detection
  26. EP260623a: NOEMA detections
  27. GRB 260909A: Mondy optical observations and afterglow candidate
  28. GRB 260909A: Xinglong 2.16m optical upper limit
  29. GRB 260909A: SVOM/C-GFT optical upper limit
  30. GRB 260909A: SVOM detection of a burst
  31. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  32. GRB 260903A: SAO RAS optical upper limit
  33. The EP-WXT trigger 01709305715 is likely a flaring star
  34. EP260903a: EP-FXT follow-up observation
  35. The EP-WXT trigger 01709302592 is likely a flaring star
  36. GRB 260903A: J-band upper limit with WINTER
  37. GRB260903A: Liverpool Telescope optical observations
  38. GRB 260903A: SAO RAS optical observations
  39. EP260903a: EP-WXT detection of a fast X-ray transient
  40. GRB 260830A: Insight-HXMT/HE detection
  41. GRB 260903A: EP-FXT follow-up observation
  42. GRB 260903A: OHP/T193 optical afterglow detection
  43. NuSTAR Transient 260828: SOAR Optical Upper Limits
  44. GRB 260903A: LCO optical counterpart detection
  45. EP260901a: SVOM/VT optical upper limits
  46. EP260901a: EP-FXT follow-up observation
  47. GRB 260829A: SVOM/GRM observation
  48. GRB 260818A: ATCA detection of a candidate radio counterpart
  49. EP260830a: EP-FXT follow-up observation
  50. EP260901a: Global MASTER-Net observations report
  51. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  52. NuSTAR Transient 260828: LCO Optical Upper Limits
  53. EP260901a: EP-WXT detection of a fast X-ray transient
  54. GRB 260831B: EP-FXT follow-up observation
  55. GRB 260831B: LCO optical upper limits
  56. EP260830a: EP-WXT detection of a fast X-ray transient
  57. GRB 260827A: SVOM/GRM observation
  58. GRB 260831B: SVOM detection of a possible burst
  59. GRB 260825A: SVOM/GRM observation of a long burst
  60. GRB 260818B: Further EP-FXT observation
  61. GRB 260818B: VLT optical and nIR observations
  62. GRB 260818B: TNG NIR observations
  63. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  64. GRB 260818B: 6 GHz VLA observations
  65. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  66. GRB 260808B: SAO RAS observations of the optical rebrightening
  67. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  68. GRB 260822A: EP/FXT follow-up observations
  69. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  70. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  71. EP260822a: EP-FXT non-detection and upper limit
  72. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  73. EP260822a: Einstein Probe detection of a fast X-ray transient
  74. GRB 260822A: LCO optical upper limits
  75. The EP-WXT trigger 01709287395 is likely a flaring star
  76. GRB 260822A: GROWTH-India Telescope Upper Limits
  77. GRB 260818B: VLA radio observations
  78. GRB 260818B: SVOM/C-GFT optical upper limit
  79. The EP-WXT trigger 01709286204 is likely a flaring star
  80. EP detected a brightening of LMXB 1ES 1735-26.9
  81. GRB 260818B: EP-FXT follow-up observation
  82. GRB 260818A: J-band observations with WINTER
  83. GRB 260818B: NOT optical upper limits
  84. GRB 260810A: SVOM/GRM observation
  85. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  86. GRB260818A: EP-FXT follow-up observation
  87. GRB 260818B: LCO optical upper limits
  88. EP260806a: SAO RAS multicolor optical observations
  89. GRB 260818A: LCO optical upper limits
  90. EP260812a: AbAO optical upper limit
  91. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  92. EP260806a: NUTTELA-TAO optical observations
  93. The EP-WXT trigger 01709281429 is likely a flaring star
  94. EP260812a: AZT-22 optical upper limit
  95. EP260806a: WFST optical observations
  96. The EP-WXT trigger 01709280562 is likely a flaring star
  97. EP260812b: Optical upper limit with Kinder
  98. The EP-WXT trigger 01709279838 is likely a flaring star
  99. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  100. GRB 260808B: Liverpool Telescope further optical observations

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