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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"

21605 results found.

  1. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  2. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  3. EP260822a: EP-FXT non-detection and upper limit
  4. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  5. EP260822a: Einstein Probe detection of a fast X-ray transient
  6. GRB 260822A: LCO optical upper limits
  7. GRB 260822A: GROWTH-India Telescope Upper Limits
  8. GRB 260822A: GOTO optical upper limit
  9. GRB 260822A: SVOM detection of a short burst
  10. GRB 260818B: VLA radio observations
  11. GRB 260818B: SVOM/C-GFT optical upper limit
  12. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  13. EP detected a brightening of LMXB 1ES 1735-26.9
  14. GRB260820A: Fermi GBM Final Real-Time Localization
  15. GRB 260818A: J-band observations with WINTER
  16. GRB 260818B: SVOM/ECLAIRs refined analysis
  17. GRB 260818A: SVOM/ECLAIRs refined analysis
  18. GRB 260818B: NOT optical upper limits
  19. GRB 260810A: SVOM/GRM observation
  20. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  21. GRB 260818B: LCO optical upper limits
  22. EP260806a: SAO RAS multicolor optical observations
  23. GRB 260818A: LCO optical upper limits
  24. EP260812a: AbAO optical upper limit
  25. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  26. EP260806a: SVOM/ECLAIRs detection through targeted search
  27. EP260806a: NUTTELA-TAO optical observations
  28. EP260812a: AZT-22 optical upper limit
  29. EP260806a: WFST optical observations
  30. EP260812b: Optical upper limit with Kinder
  31. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  32. GRB 260808B: Liverpool Telescope further optical observations
  33. EP260812a: NOT and Liverpool Telescope upper limits:
  34. EP260812b: Liverpool Telescope observations
  35. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  36. EP260812a: SVOM/C-GFT optical upper limit
  37. EP260812b: COLIBRÍ optical observations
  38. EP260812b: SVOM/VT optical observation
  39. GRB 260808A: SVOM/GRM observation
  40. EP260812b: Einstein Probe detection of an X-ray transient
  41. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  42. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  43. GRB 260810A: AstroSat CZTI detection of a long burst
  44. EP260812a: Einstein Probe detection of an X-ray transient
  45. GRB 260809A: SAO RAS optical observations
  46. GRB 260808B: SAO RAS optical observations
  47. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  48. EP260806a: MAO/AZT-22 optical observations
  49. GRB260808B: MAO/AZT-22 optical observations
  50. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  51. GRB 260809A: J-band upper limit with WINTER
  52. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  53. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  54. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  55. GRB 260809A: NOT optical observations
  56. GRB260809A: MAO/AZT-22 optical observations
  57. GRB260809A: OHP/T193 optical observations
  58. EP260809a: J-band upper limit with WINTER
  59. GRB 260808B: J-band upper limit with WINTER
  60. GRB 260808B: SVOM/ECLAIRs refined analysis
  61. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  62. GRB 260809A: SVOM detection of a faint burst
  63. GRB 260808B: Liverpool Telescope optical observations
  64. GRB 260808B: NOT optical observations
  65. GRB 260808B: LCO optical observations
  66. EP260809a: COLIBRÍ optical observations
  67. EP260809a: LCO optical observation
  68. EP260809a: OHP/T193 optical observations
  69. GRB260808B: OHP/T193 optical observations
  70. EP260809a: Einstein Probe detection of an X-ray transient
  71. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  72. GRB 260808B: SVOM/VT optical candidate from VHF data
  73. GRB 260808B: SVOM detection of a faint burst
  74. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  75. EP260806a: COLIBRÍ optical observations
  76. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  77. EP260806a: SVOM/VT optical observation
  78. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  79. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  80. EP260806a: LCO likely optical counterpart
  81. EP260806a: Einstein Probe detection of an X-ray transient
  82. GRB 260715A: cubesat Avion detection
  83. GRB 260709A: cubesat Avion detection
  84. GRB 260708A: cubesat Avion detection
  85. SN 2026stf / GRB 260708A: ATLAS forced photometry
  86. GRB 260802A: SVOM/VT optical upper limits from VHF data
  87. GRB 260802A: LCO optical upper limits
  88. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  89. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  90. GRB 260731A: AstroSat CZTI detection of a long burst
  91. GRB 260730B: AstroSat CZTI detection
  92. EP260731a: COLIBRÍ optical upper limit
  93. EP260731a: NOT optical upper limit
  94. EP260731a: Einstein Probe detection of an X-ray transient
  95. GRB 260727A: SVOM/ECLAIRs refined analysis
  96. GRB 260726A: SVOM/ECLAIRs refined analysis
  97. EP260728a: COLIBRÍ optical upper limit
  98. EP260729a: Einstein Probe detection of an X-ray transient
  99. EP260727a: SAO RAS optical observations
  100. GRB 260727A: AbAO and SAO RAS optical observations

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