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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"

20357 results found.

  1. EP Alert 260914.53: Global MASTER-Net observations report
  2. GRB 260915A: SVOM detection of a burst
  3. GRB 260914A: LCO optical observation
  4. GRB 260914A: SVOM/C-GFT optical observations
  5. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  6. GRB 260914A: SVOM detection of a burst
  7. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  8. GRB 260913A: SVOM/C-GFT optical upper limit
  9. GRB 260913A: SVOM detection of a faint burst
  10. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  11. GRB 260907A: SVOM/GRM observation
  12. GRB 260909A: CrAO and AbAO optical upper limits
  13. GRB 260909A: SVOM/ECLAIRs refined analysis
  14. GRB 260909A: KAIT optical upper limit
  15. GRB 260903A: Swift-XRT observations
  16. GRB 260909A: OHP/T193 z-band upper limit
  17. GRB 260909A: VLT optical and near-infrared upper limits
  18. EP260806a: NOEMA detection
  19. EP260623a: NOEMA detections
  20. GRB 260909A: Mondy optical observations and afterglow candidate
  21. GRB 260909A: Xinglong 2.16m optical upper limit
  22. GRB 260909A: SVOM/C-GFT optical upper limit
  23. GRB 260909A: SVOM detection of a burst
  24. GRB 260903A: SAO RAS optical upper limit
  25. GRB 260903A: J-band upper limit with WINTER
  26. GRB 260903A: SVOM/ECLAIRs refined analysis
  27. GRB260903A: Liverpool Telescope optical observations
  28. GRB 260903A: SAO RAS optical observations
  29. EP260903a: EP-WXT detection of a fast X-ray transient
  30. GRB 260903A: OHP/T193 optical afterglow detection
  31. NuSTAR Transient 260828: SOAR Optical Upper Limits
  32. GRB 260831A: GECAM-B observation
  33. GRB 260903A: LCO optical counterpart detection
  34. EP260901a: SVOM/VT optical upper limits
  35. EP260901a: EP-FXT follow-up observation
  36. Konus-Wind detection of GRB 260829A
  37. GRB 260829A: SVOM/GRM observation
  38. GRB 260818A: ATCA detection of a candidate radio counterpart
  39. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  40. NuSTAR Transient 260828: LCO Optical Upper Limits
  41. EP260901a: EP-WXT detection of a fast X-ray transient
  42. GRB 260831B: LCO optical upper limits
  43. EP260830a: EP-WXT detection of a fast X-ray transient
  44. GRB 260827A: SVOM/GRM observation
  45. GRB 260831B: SVOM detection of a possible burst
  46. EP260727a: ATCA 10 GHz detection
  47. GRB 260825A: SVOM/GRM observation of a long burst
  48. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  49. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  50. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  51. GRB 260818B: Further EP-FXT observation
  52. GRB 260818B: VLT optical and nIR observations
  53. GRB 260818B: TNG NIR observations
  54. GRB 260818B: 6 GHz VLA observations
  55. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  56. GRB 260808B: SAO RAS observations of the optical rebrightening
  57. GRB 260822A: SVOM/ECLAIRs refined analysis
  58. GRB 260809A: SVOM/ECLAIRs refined analysis
  59. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  61. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  62. EP260822a: EP-FXT non-detection and upper limit
  63. GRB 260822A: GOTO optical counterpart detection
  64. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  65. EP260822a: Einstein Probe detection of a fast X-ray transient
  66. GRB 260822A: LCO optical upper limits
  67. GRB 260822A: GROWTH-India Telescope Upper Limits
  68. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  69. GRB 260818B: SVOM/C-GFT optical upper limit
  70. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  71. EP detected a brightening of LMXB 1ES 1735-26.9
  72. GRB 260818A: J-band observations with WINTER
  73. GRB 260818B: SVOM/ECLAIRs refined analysis
  74. GRB 260818A: SVOM/ECLAIRs refined analysis
  75. GRB 260818B: NOT optical upper limits
  76. GRB 260810A: SVOM/GRM observation
  77. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  78. GRB 260818B: LCO optical upper limits
  79. EP260806a: SAO RAS multicolor optical observations
  80. GRB 260818A: LCO optical upper limits
  81. EP260812a: AbAO optical upper limit
  82. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  83. EP260806a: SVOM/ECLAIRs detection through targeted search
  84. EP260806a: NUTTELA-TAO optical observations
  85. EP260812a: AZT-22 optical upper limit
  86. EP260806a: WFST optical observations
  87. EP260812b: Optical upper limit with Kinder
  88. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  89. GRB 260808B: Liverpool Telescope further optical observations
  90. EP260812a: NOT and Liverpool Telescope upper limits:
  91. EP260812b: Liverpool Telescope observations
  92. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  93. EP260812a: SVOM/C-GFT optical upper limit
  94. EP260812b: COLIBRÍ optical observations
  95. EP260812b: SVOM/VT optical observation
  96. GRB 260808A: SVOM/GRM observation
  97. EP260812b: Einstein Probe detection of an X-ray transient
  98. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  99. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  100. GRB 260810A: AstroSat CZTI detection of a long burst

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