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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"

19565 results found.

  1. GRB 260915A: SVOM/C-GFT optical upper limits
  2. GRB 260915A: REM optical/NIR observations
  3. GRB 260914A: REM optical/NIR observations
  4. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  5. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  6. GRB 260915A: NOT optical upper limit
  7. GRB 260915A: SVOM/VT optical upper limits from VHF data
  8. GRB 260915A: LCO optical upper limits
  9. EP Alert 260914.53: Global MASTER-Net observations report
  10. GRB 260915A: SVOM detection of a burst
  11. GRB 260914A: LCO optical observation
  12. GRB 260914A: SVOM/C-GFT optical observations
  13. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  14. GRB 260914A: SVOM detection of a burst
  15. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  16. GRB 260913A: SVOM/C-GFT optical upper limit
  17. GRB 260913A: SVOM detection of a faint burst
  18. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  19. GRB 260907A: SVOM/GRM observation
  20. GRB 260909A: CrAO and AbAO optical upper limits
  21. GRB 260909A: Swift ToO observations
  22. GRB 260909A: KAIT optical upper limit
  23. GRB 260903A: Swift-XRT observations
  24. GRB 260909A: OHP/T193 z-band upper limit
  25. GRB 260909A: VLT optical and near-infrared upper limits
  26. EP260806a: NOEMA detection
  27. EP260623a: NOEMA detections
  28. GRB 260909A: Mondy optical observations and afterglow candidate
  29. GRB 260909A: Xinglong 2.16m optical upper limit
  30. GRB 260909A: SVOM/C-GFT optical upper limit
  31. GRB 260909A: SVOM detection of a burst
  32. Fermi trigger No 810554827: Global MASTER-Net observations report
  33. EP Alert 260908.60: Global MASTER-Net observations report
  34. GRB 260903A: Swift ToO observations
  35. GRB 260903A: SAO RAS optical upper limit
  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 260903A: OHP/T193 optical afterglow detection
  41. NuSTAR Transient 260828: SOAR Optical Upper Limits
  42. GRB 260903A: LCO optical counterpart detection
  43. GRB 260903A: SVOM detection of a soft faint burst
  44. EP260901a: SVOM/VT optical upper limits
  45. GRB 260829A: SVOM/GRM observation
  46. GRB 260818A: ATCA detection of a candidate radio counterpart
  47. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  48. NuSTAR Transient 260828: LCO Optical Upper Limits
  49. EP260901a: EP-WXT detection of a fast X-ray transient
  50. GRB 260831B: LCO optical upper limits
  51. EP260830a: EP-WXT detection of a fast X-ray transient
  52. GRB 260827A: SVOM/GRM observation
  53. GRB 260831B: SVOM detection of a possible burst
  54. EP260727a: ATCA 10 GHz detection
  55. GRB 260825A: SVOM/GRM observation of a long burst
  56. GRB 260818B: Further EP-FXT observation
  57. GRB 260818B: VLT optical and nIR observations
  58. GRB 260818B: TNG NIR observations
  59. GRB 260818B: 6 GHz VLA observations
  60. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  61. GRB 260808B: SAO RAS observations of the optical rebrightening
  62. EP Alert 260820.31: Global MASTER-Net observations report
  63. GRB 260822A: SVOM/ECLAIRs refined analysis
  64. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  65. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  66. EP260822a: EP-FXT non-detection and upper limit
  67. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  68. EP260822a: Einstein Probe detection of a fast X-ray transient
  69. GRB 260822A: LCO optical upper limits
  70. GRB 260822A: GROWTH-India Telescope Upper Limits
  71. GRB 260822A: SVOM detection of a short burst
  72. GRB 260818B: SVOM/C-GFT optical upper limit
  73. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  74. EP detected a brightening of LMXB 1ES 1735-26.9
  75. GRB 260818A: J-band observations with WINTER
  76. GRB 260818B: SVOM/ECLAIRs refined analysis
  77. GRB 260818A: SVOM/ECLAIRs refined analysis
  78. GRB 260818B: NOT optical upper limits
  79. GRB 260810A: SVOM/GRM observation
  80. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  81. GRB 260818B: LCO optical upper limits
  82. GRB 260818B: SVOM detection of a short burst
  83. EP260806a: SAO RAS multicolor optical observations
  84. GRB 260818A: LCO optical upper limits
  85. EP260812a: AbAO optical upper limit
  86. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  87. GRB 260818A: SVOM possible detection of a long and faint GRB
  88. EP260806a: NUTTELA-TAO optical observations
  89. EP260812a: AZT-22 optical upper limit
  90. EP260806a: WFST optical observations
  91. EP260812b: Optical upper limit with Kinder
  92. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  93. GRB 260808B: Liverpool Telescope further optical observations
  94. EP260812a: NOT and Liverpool Telescope upper limits:
  95. EP260812b: Liverpool Telescope observations
  96. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  97. EP260812a: SVOM/C-GFT optical upper limit
  98. EP260812b: COLIBRÍ optical observations
  99. EP260812b: SVOM/VT optical observation
  100. GRB 260808A: SVOM/GRM observation

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